GEORGIA ),1 allua] all Uniform Traffic Control Devices for Streets and Highways ~IARCH 195/. A dopted by the State Highway Board of (~eorgiH for use by the State Highway Department of Georgia and the Counties and Munir.ipalities and all other jurisdictions within the State, in accordance with Article Ill, Section 31, of Act ~ o. 8.54 approved .January 11, 19M, (Georgia Laws 19.53, :November-December Session, pp. 556-623). Printed alld distrihuted hy STATE HIGHWAY DEPAHTMENT OF GEORGIA x o. 2 Capitol Square Atlanta 3, Georgia RESOLUTION OF THE STATE HIGHWAY BOARD OF GEORCHA ADOPTING THE MAl\TAL A:\D SPECIFICATIONS FOR THE FNIFORlVI SYSTK'vI OF TRAFFIC CONTROL DEVICES (~eorgia, Fulton ('OIll1ty. Whereas, the (;eorgia General Assembly in its i\Tovember-December, 19.5:3. Session adopted, and the Governor of the State, on January 11. 19,54, approved Act :\0. 854 Cniform .4.eI Regulating Traffic on Highways; and Whereas, Sedion :31, Article III, of the Act directs that: "The State High\\'a~' Board ::;hall adopt a YIanual and Sper'ifications, as recommended by the Engineering Division of thp State Highway Board, for a uniform system of traffic-r'ontrol dpvices consistent with the provisions of this Act for usc upon all highways within this State. Such uniform system shall cOlTelatp \vith and so far as possible conform to the system then current as approved by the Amerir'an Association of State High\\'ay Officials." Whereas, the Engineering Division of the State Highway Department has recommended through its State Highway Engineer that the attached Manual on Un~form Traffic Control Devices for Streets and Highways in Georgia, March 1954, be adopted in compliance with said Act No. 8,54, IT IS THEREFORE RESOLVED, AND IT IS HEREBY ORDERED, That the said Manual on Uniform Traffic Control Devices for Street8 and Highways in Georgia, March 1954, be and the same is hereby adopted by this Board as directed by said Act, and same is declared to be the official manual and specifications to control and govern any traffic control device or devices erected or to be erected, installed or III to be installed, placed or displayed, on any street or highway within this State. Recommended this 24th day of March, 19;')4. ::-ltate Highway Engineer Approved this 25th day of March, 1954. STATE HIGHWAY BOARD OF GEOHGIA Chairman Member Member iv RESOLUTION OF THE STATE HIGHWAY BOAR;) OF GEORGIA ADOPTI NG THE REVISIONS TO MANUAL AND SPECIFICATIONS FOR THE UNIFORM SYSTEM OF TRAFFIC CONTROL DEVICES Georgia, Fulton County. 1r1hereas, the State Highway Board of Georgia did on March 24, 1954, adopt a Manual and Specifications for the Uniform System of Traffic Control Devices in accordance with Section 31 of Act No., 854, the Uniform Act Regulatin~ Traffic on Highways, adopted by the Gene=a':' Assembly of Georgia at its November-December Session 1953, and approvec by the Governor of the State on January 11, 1954j and Whereas, it has been deemed expedient that said Manual be amended in order to conform more closely and correlate with the System now current as approved in 1954 by the American Association of State Highway Officials as required by said Act: IT IS THEREFOP.E RESOLVED, AND IT IS HEREBY ORDERED that the following described parts of the MaDual adopted March 24, 1954, be and they are hereby amended as described in each instance. /'! Recommended.this 6th day of April, 1956. .. '.,' /Ih)~'~-'1"'" ~ '-'~ .'~ ( <.,t...:.: J, J:( .;h./' /l- 0- .1-/&.~ State Highway Engineer Approved this 12th day of April, 1956. STATE HIGHWAY BOARD OF GEORGIA REVISIONS TO GEORGIA MriNUAL ON UNIFORM TRAFFIC CONTROL DEVICES FOR STREETS AND HIGlMAYS APRIL 1956 PART I - SIGNS Standardization of Position. On raJe 7 delete th?refrom the fifth and sixth unnumbcr0d parasraphs and substitute therefor the following: "Signs in rural areas should normally be mounted at 3 heiJht of 2t least 5 feet above the crown of the pavement to the bottom of the sign. However, where parkin] is likely tc occur, or where oth0r C~[t~uctions are present, the height should be at least 7 feet to the bottom of t~e sign. In business and in resid0ncc districts signs should be mounted at least "/ feet high to the bottom of the sign." Design of Stop fi.9.D.... On page 13 delete in its entirety and SUbstitute in lieu thereof the following: "Owing to the importance of Stop signs they are given a distinctive shape (actaeon) and color (red). The r0d color is consistent with the accepted use of a red light as a Stop signal and of the color red as a special warning of danger. - 1- The Stop sign shall be octangonal in shape, shall have a red background, and shall carry the word STOP in white letters at least onethird the height of the sign. The Stop sign with yellow background and black lettering now in position may remain until replacement or refinishing is required, with full legal status. All Stop signs erected hereafter will have a red background, and white letters." Reflectorization or Illumination. On page 14 delete therefrom the first and second paragraphs and substitute therefor the following: "All Stop signs shall be illuminated or reflectorized at least in the lettering. Illumination may be by floodlight or by fixed white light in the letters. Reflectorization may be by white or clear reflecting units or reflecting coating in the letters, with or without a red reflecting coating on the background. In addition to such illumination or reflectorization, a flashing red signal, in operation both by day and by night, may be incorporated in the face of the sign or placed just above it." Speed Zone Ahead Signs R-6, R-7 On page 22 add thereto after third paragraph the f~11owin9 paragraph: "If the speed zone exceeds three miles in length, the sign shall indi~ate its approximate length." -2- No Passing Siqn R-16. On pages 26 and 27 delete said paragraphs in their entirety and substitute in lieu thereof the following: D0 NOT PAS S R-l6 24" x 30" "Do Not Pass Sign R-16 The Do Not Pass sign may be used on two and three-lane roads at the beginning of a zone through which restricted sight distance makes overtaking and passing hazardous. It shall have black letters on a white b~ckground, and be of a minimum size of 24 inches by 30 inches. There will be a 5/8" black border, 3/8" from edge of sign. It shall be erected at the right-hand side of the roadway at a height of 5 feet to the bottom of the sign, not less than 6 feet nor more than 10 feet from the edge of the roadway. Because a driver about to pass a vehicle ahead often has only restricted view to the right, an additional sign on the left-hand side of the road may be desirable. The sign normally should be supplementary to standard pavement markings as described in Part II, Section B, Pavement and Curb Marking, Page 103. Where pavement markings are well maintained, and weather conditions are not likely to hide the markings, the Do Not Pass sign need not be used." -3- End No Passing Zone Sign R-17. On page 27 delete therefrom all of said paragraph in its entirety and substitute therefor -'--, the flollowing: PAS S I I WIT H J CAR E "Pass With Care Sign R-17 The Pass With Care sign may be used at the end of a no-passing zone where Do Not Pass sign has been erected at the beginning. It shall be of the same size and color, and shall be erected in the same manner as the Do Not Pass Sign." R-17 24" x 30" Location of Warning Signs. On page 39 delete therefrom the second paragraph of said section the height of 4' of said sign and substitute therefor the height of 5' so the amended paragraph will read as follows: "In rural and residence districts where no parking occurs, Warning signs shall be erected not less than 6 feet nor more than 10 feet from the edge of the pavement or traveled roadway, with the lowest edge of the sign not less than 5 feet above the roadway, except as hereafter indicated. In any location where they will obstruct sidewalks or pedestrian paths, however, they should be mounted at a height of not less than 7 feet to the bottom of the sign. -4- In residence and business districts where parking is frequent, they shall be so set that the bottom of the sign is not less than 7 feet above the top of the curb and lefthand edge not less than one foot back from the outside edge of the curb." PART III - SIGNALS Meaning of Color and Arrow Indications. On page 133, for subti tIe "Yellow alone or Caution when shown foHowing the green or Go" there is substi tuted: "Steady Yellow alone or Caution when shown preceding red or Stop." For subtitle "Red alone or Stop" there is substituted: "Steady red alone or Stop." For subtitle "Red with green arrow" there is substituted: "Steady red with green arrow." Accident Hazard. On page 163 delete therefrom the second numbered warrant in first said paragraph and substitute therefor the following: "2. Five or more reported accidents of types susceptible of correction by a traffic control signal have occurred within a 12-month period, each accident involving personal injury or property damage to an apparent extent of $50 or more; and" - 5- -~eneral Design Requirements. On page 200, delete therefrom the sec-ondlpproved design for pedestrian control signals, )eing the second of the, two number 2 paragraphs lear the top of page and substitute therefor the :ollowing: "2. A Rectangular box-type signal in which the words WALK AND DON'T WALK are properly illuminated. " ~w Signs to be Added to Manual Ordered by Georgia ~ Throwing of Trash Sign (Information-6) THROWING TRASH-GARBAGE ON HIGHWAY PROHIBITED MAXIMUM $1,000 FINE . AND/OR IMPRISONMENT 1-6 36" x 36" The Thr1wing of Trash Sign will be 36" x 36" in size, black lettering on white background. This sign is not reflectorized except in a few special locations near or on edge of cities. These signs will be placed on outer edge of shoulder at right angle to roadway with message facing approaching traffic. Lettering sizes are: First four lines 4" Series "0" letters and the last two lines, 2" Series "0" letters. Sign will have a 3/4" black border, 1/2" from edge of sign and sign will oe erected so that the bottom of sign is 5' above center of pavement. These signs will be placed facing ~raffic leaving each incorporated ~0wn or city and at other locations where the traveling public is using high'tlay right-of-way to dump trash or garbage. - 6- Limited Access Highway Sign (Information-7) - The Limited Access Highway Sign will be 30" x 24" in size with black lettering on white background. This sign will not be reflectorized. Letter sizes are: Lines 1 and 2, 2" Series "C" letters, lines 3 and ---------- - - - 4, 1" Series "C" letters, LIMI TED-ACCESS lines 5 and 6, 1-1/2" HIGHV'JAY f Series "C" letters, I lines 7, 8 and 9 are 1" INVESTIGATE LAW BEFORE PLANNING Series "Gil letters, and IMPROVEMENTS TO ABUTTING PROPERTY line 9 will give location L l STATE HIGHfJAY BOARD OF GEORGIA CONTACT DIVISION ENGINEER STATE HIGHWAY DEPARTMHJT G~I of Division Office. These signs will be erected on or near right-of-way line 1-7 parallel to and facing 24 1t x 301t roadway. These signs will be at least 5' from bottom of sign to ground line. These signs will be located at frequent intervals alternating from one side to the other along the seg- ment of roadway which has been designated as Limited Access. -7- CONTENTS yoreword Page ~___________ 1 State Highway Board to adopt manual of uniform traffic control devices_ ___ 1 State Highway Board to sign all State Highways ________________________ 1 Local traffic control devices " _ ""_______ 2 PART I-SIGNS A-Introduction: Legal authority- "- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - :{ Classification of signs " ____ ________________________ :~ Excessive use of signs . _____________ _______ _ _________ _________ 4 Standardization of signs __________ "_ ___________ _________ 4 Sign shapes __ _- _- _- _- - - - - - - - - - -" - - _- _- _- - " 4 CoioL _- - - - - . Dimensions ___ -------- ----- - - ,') - _- ________ 5 Symbols __ . - _- _- - - - - - - - - _- - _- __ 5 Word messages _- - _- - - - - . - - - - - _- _- _- __ 5 Lettering - - - - - - _- - - - - - Illumination and reflectorization ____ -------_ (j _________ _____________ () Means of illumination_ ________________ _____________ {) Means of reflectorization __ - _- - - _- - - _- ________ (j Sign borders - - _- - - - __ - - _- _- - _- ________ () Standardization of position - _____ _. _ ________ 7 Standardization of application_ ____ Erection_ ___ ____ _ - __" _________ 8 ___________ 8 Materials__________ !) Sign posts and their foundations_ ______ !l Maintenance __ ___ . _______ !l Height and lateral location of signs. 10 B-Regulatory Signs: Application of regulatory signs_ 12 Classification of regulatory signs_ 12 Design of regulatory siiI1s _ 12 Other regulatory signs_ _______ _ _ 13 Stop sign ___________ _ _ 1:{ Design of Stop sign _ 1:3 Refleetorization or illumination 14 Warrants for Stop sign_ ____ __ 14 Location of Stop sign _ 14 Size of Stop sign to be used __ 15 Yield Right-of-Way signs _ ](j Warrants for Yield Right-of-Way signs_ 19 Location of Yield Right-of-Way signs _ H) Speed Limit sign _ 20 Location of Speed Limit sig;IL _ _ _ 2\ Speed Zone Ahead sign_ _ . 22 Turn Prohibition signs_ _ _ 22 v Page No-Passing sign - End N 0-Passing Zone sign ____ ___ - - ____________ _ _ 26 _ 27 No Passing ~hen Yellow Line is Right of Centerline sign _ 27 Keep Right Except to Pass sigrL __ ______________ Keep Right sign _________ _____ ___________ __ _ Do Not Enter sign___ __ _ One-Way sign _______________ _______________ _ Two-Way Traffic Ahead sign _______ ______ ___________ _ Parking and Stopping signs ____ ______________ _ No Parking on Pavement sign _____ _ Pedestrian Crossing signs ______ _____ _ _____ ___ 27 _ 28 _ 28 _ ao _ :~O _ :~2 _ :~:~ _ :3a Road Closed sign_ _ ______________ __________ Stop for School Bus Loading and Unloading _______ _ __ _ _ _ 34 :H Traffic Signal Speed sign ____________________________ _ _ Load Limit sign ____________________________________ _ Other Regulatory signs _____________________________ _ :34 _ 35 _ 35 C-Warning Signs: Application of warning signs _ :37 Design of warning signs _ :37 Location of warning signs_ ___________ _ _ 3~l Curve sign ____ _____ _ _ :~g Turn sign .. ___ _ _ 41 Reverse Curve sign __ _ _ 41 Reverse Turn sigrL __ ________ ___ 42 Supplemental Curve and Turn signs __ 4:~ Winding Road sign __ 4,~ Stop Ahead sigrL _ 45 Signal Ahead sign 4(j Hill sign_ 47 Bump sign_ 47 Dip sign _ 47 Pavement Narrows sigrL ___ __ 4\l Two-Lane Pavement Ahead sigrL 4!l Two-Lanes (with 4 arrows) sign 52 Divided Highway Ahead sigrL __ ,52 Divided Highway Ends sign .~;) Narrow Bridge sign _ 54 One-Lane Bridge sign_ 54 Pavement Ends SiglL _ ,55 Low Clearance sigrL _ 56 Fresh Oil sign .57 Men Working sign _ 57 Soft Shoulders sign_ 58 Slippery When Wet SigrL _. __ 58 Double Arrow sigrL _ .58 Railroad Advance Warning sigrL ___ _ _ 59 Railroad Crossbuck sign _ 60 Crossing signs _ 61 Advisory Speed sign _ 62 Cattle Crossing sign __ 62 Watch for Cattle sign ___ _ _ 64 Detour Ahead sign __ 64 VI Draw Bridge Ahead siglL _ Draw Bridge sign Cross Road sign _ Side Road sign ______ _ T Symbol sign - - _- _- - - Y Symbol sign _______ _ Business District SiglL ___ _____________________ __ _ Residence District sign ________________________________ _ Roadside Park sign ---_ _ - _ Other warning signs -- - - -- -- - _ Page 64 65 66 _ 66 _ 67 _ 67 _ 68 _ 68 68 68 D-Guide Signs: Application of guide signs________ _ _ 69 Design of guide signs __ - _- - - _- - - - - - - - - - - _- _- - - - 69 Route markers and auxiliary markers - ______________ _ _ 6f) Junction sign __ - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - _- __ 69 U. S. Route Marker- - - - - - - - - -- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - 70 State Route Marker. -- - - - - - - - - - - - - - - - - - - - - - - - - - - - __ - - _ 70 Confirmation and Reassurance Markers ______ ___ _ _ 70 Directional Markers_ - -- - - - - - - - - - - - - - -- - - - -- - - - - - - - - __ - - - - - 71 Destination Markers_________ ------ --- _ 71 Distance Marker _- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - _- 71 Ends Marker 24" x 18"- - _- - _____ _ _ 72 U. S. Oversize Route Marker- - - - - - - - - - - - - - - - - - - - - - - _- - - - - _- __ - - - 74 Georgia Oversize Route Marker __ - - - __ - - _- -_ ________ _ Directional Arrow Panels _______ _ Ends Marker 13" x 10" - ____ __- _ 74 _ 75 _ 75 Temporary Marker ------- - _- - - - - _- - - 75 Alternate Marker _- _- - - _- - - _- - - - - - - - - - - - - - - - -- - _- _- __ - - _- _- _- 75 By-Pass Marker. - _- _ _ - ______ _ _ 76 Business Route Marker. ______ _ _ 76 Cardinal Direction Marker. ___ _ - ______________ _ _ 76 Secondary Destination Marker _ _ _ 77 Information signs_ __________ _________ _ _ 77 State Line sign ____________ _ _ 77 City Limit sign__ __________ _ _ 78 County Line sign _________ __ _ _ 78 Unincorporated Village sign _ 78 Right-of-Way signs _ 7!l Guide signs for major junctions and intersections _ 79 Junction Assembly _________________ _______________ _ _ 79 Route Direction Marker Assembly ____ _ _ 80 Route and Destination Assembly ___ ______________ _ _ 82 Confirmation Marker Assembly' ___ ___ ___________ _ _ 84 Rural Reassurance Markers _ 85 Guide signs for secondary routes and intersections: Application of Secondary Guide signs Design of Secondary Guide signs Secondary Route Markers and Auxiliary Markers Secondary Junction Assembly Secondary Route Direction Assembly Secondary Route and Destination Assemblv Secondary Junction PaneL __________ . _ 85 _ 85 _ 85 _ 87 _ 87 _ 8f) 89 vii Page E-School Sign Standards: School Zone sign_ _____________________________ __ ___________________ _ 92 School Crossi~ sign _____________________________ ____________________ 92 School sign_ ___ ___________________________________ _ __________________ 93 School-Speed Limit signs_ _____________________________________________ 93 No Parking School Hours sign ________ ________________________________ 94 Portable School sign_ _________________ __________ ___________________ 94 PART II-MARKINGS A-Introduction: Functions and limitations of markings_ ________ ________________________ !J7 Legal authority - - __ _ - - - __ - - _____________ 97 Standardization_ ____________________________________________________ 97 Types of markings ___________________________________________________ 97 Materials ___________________________________________________________ !l8 Color8_________________ _ 100 Types of striping _____ _______________ _________________ 101 Width of lines - _ _________ _____________ 102 Reflectorization_ __________________________________ __________ ____ 102 Maintenance __________________ _______________ _________ 102 B-Pavement and Curb Markings: Center lines -_ Center lines on rural roads _ Center lines on urban streets _ Lane lines - - __ - - _- - - _- - - _ _- _- _- _- _- Lane lines on rural roads - -_ Lane lines on urban streets_ ___ _ No-passing zones - _ - -_ No-passing zones on two- and three-lane roadways Warrants for no-passing zones_ _ __ _ _ Pavement edges '_ Pavement-width transitions_ Approach to an obstruction _ Streetcar clearance lines __ Turn markings _ Transverse lines _______ Stop lines_ _____ _ __- -_ - - Cross-walk lines _ Route direetions _ Approach to railroad crossing __ Parking space limits_ ______ ___ _ _ Word markings_ Curb markings for parking restrict ions lQ;~ 1O;~ lQ;~ 104 104 _ 104 105 __ 105 107 107 110 110 1l:3 114 114 114 116 116 116 118 118 _ 11\1 C-Object Markings: Application of objeet markings _______ __ _______________________ _ 120 Objects within the roadway _ 120 Lighting or refiectorization of obstructions_ __ _______ __ 121 Object markings on curbs _ 121 Objects adjacent to the roadway __ 121 viii Page D-Reflector Markers: Application of reflector markers _______________________________________ 123 lIazard markers 123 Delineators _____ _____________________________________________________ 123 PART III-SIGNALS A-Introduction: Definitions_ ________ _ - _- - ______________ 127 Value of signals_ ___ - - - ______________ 127 Standardization- - __ __- - - _ - - __ - - - __ - - ______________ 128 Legal authority - __ - - _- -- -- 129 Classification- - - - __ - - __ - - - - __ - - __________ 12H B-Features Common to Fixed-Time and Traffic-Actuated Signals: General aspects of signals __ - _- - - - - - - - - - - __ - - - - - - - - - - - - - - _- - - __ - - - __ 131 Design for future needs __ - - - _- - - - - - - - - - - _- - - - - - - - - -. - - - __ - - - __ 131 Number of lenses per signal face - - - - - - - - - - - - - - _- - - _- - - __ - - __ 131 Color and position of lenses __ - - - - _- _- _ - - - - ______ _ _ 132 Meaning of color and arrow indications_ - - - - - - _- _- - - - _ 1:~2 Shapes and dimensions of lenses - _- - - _- - - _- - - _- - - __ - -_ 1:~5 Lettering on lenses __ - - - - - _- - - - - - - - - _- - -_ 13,5 Illumination of lens _- - - - - - - - - - - - - - _-- - _- - - _- 13G Visibility and shielding of lens - _- _- --- - - _ lin Auxiliary illuminated signs - _- _ _- _ I:n Number of signal faces - _- _- - - - - - - _- - - _- _- _ lin Limit of signal-controlled area __ - _- - - - - - - - _- - - - - - - _- 1:38 Location of signal faces at intersections_ - - - __ 138 lIeight of signal faces - -- _ 1:3U Pointing of signal faces - -- _ 141 Location in relation to curb lines - _ 141 Location in relation to the pavement or traveled surface. _ 141 Removal of confusing advertising lights or display of unauthorized signs, signals or markings_ __________ _ _ 142 Provision for future installation __ 142 Types of mounting for signal heads _____ _ _ 14:~ Installation of underground conduit or cable __ 14:~ Selection of cable _ 144 Insulation of cable _ 145 Cable positions and clearances _ 145 Messenger wires _ 145 Efficiency and continuity of operation _ 14.5 Length of cycle _____________________ __ 146 N UIp.ber of traffic phases _ 14G Rotation of intervals ________ _ _ 147 Traffic movement intervals proportioned to traffic requirements_ ___ 147 Unexpected conflicts during Go intervals __ 148 Vehicle-clearance intervaL _ 148 Adequacy of maintenance _ 14\) Signal lamp replacement. _ 14!l . Cleaning___ _ _ \.'>0 Maintenance of controllers __ 150 IX Painting records ~iaintenance Page 151 151 C-Comparison.,n Fixed-Time and Traffic-Actuated Control: Relative adaptability to normal intersection requirements 152 Special merits of fixed-time controL ____________________________________ 153 Special merits of traffic-actuated controL _______________________________ 153 Other factors governing selection of type of controL 154 D-Fixed-Time Signals: I>efinition 156 Advance engineering data required _____________________________________ 156 Warrants for fixed-time signals - - __________________________ 156 Minimum vehicular volume - - - __________________________ 157 Interruption of continuous traffic_ ___ - _- - " 159 Minimum pedestrian volume 161 Coordinated movement 162 Accident hazard 163 Combination of warrants-other factors_ _______________________________ 165 Selection of type of fixed-time control mechanism 165 Nonsynchronous fixed-time controller for isolated intersections 165 Program type of fixed-time controller for isolated intersections 166 Synchronous type of fixed-time controller for isolated intersections 166 Controllers providing for coordination 166 Signal timing in accordance with traffic requirements 167 I>ivision of total cycle timc 167 Coordination of fixed-time signals 169 Types and selection of coordination ~_ _ 169 Simultaneous system _________________________________________________ 169 Alternate system_ ____________________________________________________ 170 Simple progressive system_ __________________________________ __________ 171 Flexible progressive system_ ___________________________________________ 172 Conditions affecting efficiency of signal system __________________________ 173 Manual control 173 Speeds for progressive systems_ ________________________________________ 174 Signs indicating timed speed __________________________________________ 174 Coordination with railroad crossing signals_ _____________________________ 174 Rate of f1ashing 175 E-Traffic-Actuated Signals: Definition 176 Warrants for intersection controL 176 Warrants for nonintersection controL __________________________________ 178 Types of traffic-actuated control, and factors governing selection 178 Semi-traffic-actuated control_ _________________________________________ 178 Full traffic-actuated controL 179 Coordinated control 180 Pedestrian-actuated controL 181 Speed control 182 One-way restricted zone controL ______________________________________ 183 Detectors and controllers _____________________________________________ 184 Types of detectors ___________________________________________________ 184 Pressure-sensitive detectors ___________________________________________ 184 x Page Magnetic detectors_ _______ _ - - Sound-sensitive detectors_ ___ _____________________ _ Light-senitive detectors_ __ _ - _ 185 _ 185 _ 185 Pedestrian push-button detectors _______ _____________________ ____ ___ 185 Types of controllers - - ~ _ 185 Two-movement, semi-traffic-actuated controller with time extension _ 186 Two or more movements, full or semi-traffic-actuated controller with time extension _ 186 Traffic-actuated speed control for nonintersection loeations _ 187 Two-movement, full or semi-traffic-actuated controller with speed controL __ 187 Two-movement, full traffie-aetuated controller with automatic adjustments of periods with respect to traffic volume, relative density, and elapsed time_ 187 Two-phase, full traffic-actuated control for one-way restricted zone _ 188 Additional flexibility for controllers used in coordinated systems _ 188 Provision for manual operation _____________ _ _ _ 188 Installation of traffic-actuated signals _________ _ _ 188 Distance of vehicle detectors from stop line _ 189 Location of vehicle detectors from center line_ . _________ _ _ 191 Installation of pedestrian detectors - _ 192 Installation of streetcar detectors - ________ _ _ 192 Operation and adjustment of traffic-actuated signals_ _ _ _ 192 Continuous operation __ - - - - - - - - - - - - - -- - - - - - - - - - - - __ . - - - - - - - - _ 192 Time intervals and adjustments - - - - - - - - __ - - - - - - _- _- - - - - _- Interval sequence_______________________________ _ Rotation of phases_ _________ ___ - _ 19:~ _ 196 _ 196 F-Special Pedestrian Signals: Definition - - - - - - - - - - - - - - - - - - __ - - - - - - _- _- - - - - - _ 198 VVarrants - _ 198 Type of controL -- - -- _ 199 General design requirements _ 199 Meaning of indications _ 200 Location _ 201 Operation _ 201 Phases and intervals _ 202 G-Other Special Traffic Signals: Types of special traffic signals _ Flashing beacons and signals: Definition and application _ 20:~ VV a r r a n ts _ 20:~ Types of controL ________________ _ _ 204 I)esign _ 205 Location _ 205 0peration . _ 205 Lane-direction traffic signals: Definition and application _ 206 VVarrants ~~~~:~~~~~~r~~-~~~~~-~~~~~~-~-~-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~_~~~ 206 206 207 Location _ 207 Operation _ 207 Xl Page Traffic signals at drawbridges: Application _____________________________ ____________ _ 207 Warrants _~_ ____________________________________________ .. _ 208 Design . _________ 208 Location_ _ . 208 Operation_ ___________________________________________ _ 208 H-Train-Approach Signals and Gates: Railroad grade-crossing protection _ 209 Train approach signals: Classification and definition _______ ___________________ _ _ Warrants Types of controL I)esign Location Installation Operation Maintenance_ __________________ _ .. _ 209 _ 209 _ 209 _ 209 _ 210 _ 210 _ 210 _ 211 Railroad-highway grade-crossing automatic gates: Application_ _________________________________________________ _ Warrants Types of controL Design _ Location_ _________________________ _ _ 1nstallation_ _______ _______________ _ _ Operation ._ _ _ Maintcnance .. _ _ 211 _ 211 _ 212 212 212 212 212 21:~ PART IV-ISLANDS A-Introduction: Function of islands 215 General engineering requirements_ _____ __________________________ 21.5 C lassification_ ________________________________________________ 2H\ Standardization_ _________ _______________ ___________ 2H\ B-Loading Islands: Legal authority_______ _ 218 Functions_ _______ ______________________________________ __________ 218 Warrants___________ __ _ 218 Location ________ _ ______ _____ ____________________________ 218 Access_. 2Hl Elements of design_ ___ 219 Designation of arca ____ 219 Dimensions ____ _. _____ 220 End protection_ ______ ___ 220 Approach-end treatmenL_______ _. _ __ 221 Side protection_ __ _______________ 222 Illumination and reflcctorization_ ___ ________ _ .__ . _ 222 Dircction of flow_ Signs _________ _ _________ _ . 223 ___ ________ _______________ __ 2Z~ Markings .. ___________________________________________________ 223 Summary specifications for loading islands_ ____ ___________________ 224 Xli C-Refuge Islands: Legal authority _ Functions _ \Varrants _ Location - Elements of design. Designation of area _ Continuous median strip_ Dimensions - _- - - - - - - - - - - - - - - End protection- - - - - - Approach-end treatmenL __ Side protection - - - - - - - - - - - - - - - - Illumination and reflectorization Signs __ - - - - -------- Markings __ - - - - - - - - - - - - - - - - - - - - - - - - - - Summary specifications for refug(; islands __ D-DivisionaIIslands: Legal authority- - - - -- Functions --- Warrants - - - - -. -- Elements of design __ Designation of area _ Dimensions - _- - Curbs _ Approach-end treatment __ Illumination and reflectorization _ Signs - - - _- __ - Markings _________ __ ________ _ _ Summary specifications for divisional islands_ E-Channelizing Islands: Legal authority _ Functions_ __ __________ _________ __ warrants_ Elements of design __ _________ __ Designation of area_ Dimensions _ Curbs_______________ _ _ Approach-end treatmenL ___________ _ _ lIIumination and reflectorization_ __ _ __________ _ _ Signs _________________________________ __________ _ Markings Summary specifications for channelizing islands_ _ _ 22,5 225 225 226 226 226 227 228 228 22D 22D 229 22fl 22fl 2:~0 240 240 240 240 241 242 244 244 244 _ 244 _ 245 245 APPENDIX A Glossary of traffic signal terms _ _ 246 APPENDIX B Illustrated index for signs and markers _ 250 Xlll ILLUSTRATIONS Page Figure I.-Stop signs-typical installations _ 17 Figure 2.-Tytifcallocations for Stop signs _______ _____ _______ _ _ 18 Figure 3.-Turn Prohibitions signs-typical installations. . _ 2:~ Figure 4.-Typical installation of signs at end of one-way street __ . . 24 Figure 5.-Portable turn prohibition signs-typical installations _ 25 Figure 6.-One Way signs-typical installation . . _ 29 Figure 7.-Parking signs-typical installation . _ :H Figure 8.-Curve signs-typical installation. _______ _ . ______ _ __ 38 Figure 9.-Reverse Curve signs-typical installation . _ 40 Figure 1O.-Typical sign installations-transition from 2-lane to 4-lane highway _____________ _____________ ___ _____ ___________________ 48 Figure ll.-Typical sign installation-transition from 2-lane to divided high- way . _________________________________________ 50 Figure 12.-Typical sign installations-transition from 2-lane to divided high- ~-ay__________________________ 51 Figure 13.-Detour signs-typical installations_ _ _ _ ___________________ 63 Figure l4.-Typical installation of guide signs for major routc intcr- sections.. . . _. . . opposite n Figure 14A.-Typical alternate installation of guide signs for major inter- sections (for one dircction of travcl only) . . opposite 73 Figure 15.-Typical installation of guide signs at "Y" intmsection _ 73 Figure 16.-:\'Iethods of erection for destination markers _ 83 Figure 17.-Spacing of routc markcrs in rural areas . _ 86 Figurc 18.-0versize statc and U. S. directional route markers _ 88 Figurc 19.-Typical installation of guide signs for ~econdary route intersections_ 90 Figurc 20.-Standard location and ercction of school signs . 95 Figure 21.-Position of signs in rural and urban areas . . _ 96 Figurc 22.-Standard pavcment markings for no-passing zones _ 106 Figurc 23.-Method of locating and dctcrmining the length of no-passing zones on vertical and horizontal curves _________ _____________ _____ __ ___ 108 Figure 24.-Typical pavement-width transition markings . ___ 109 Figure 25.-Approach markings for obstructions in the roadway ... III Figure 26.-Typical designs for turn markings on pavements__________ 112 Figure 27.-Typical urban pavement markings, showing center lincs, parking- space limits, and route markings. __ _____ _ . 115 Figure 28.-Standard pavement markings at railroad crossings_ _______ 117 Figure 2\J.-Typical markings on objects in and adjacent to the roadway 122 Figure :~O.-Arrow lens design; Institute of Traffic Engineers . ______ 136 Figure 31.-Location standards marked "Ped" apply to intmsections where pedestrian volumes equal or exceed the warrant values_ ______________ __.. 140 Figure 32.-(Above) WALK lens design, Institute of Traffic Engineers. (Be- low) A typical WAIT lens design 201 Figure 33.-WALK-WAIT signal installation .__ _ 202 Figure 34.-A raised loading island with no protection other than pavement markings. No turns are permitted at this intersection _ 216 Figure 35.-A raised loading island in business district. Also serves as a protec- tion for left turn movement 217 Figure 36.-A concrete loading island with end protection provided by a con- crete buffer, six-inch red reflectors and concrete painted with black and white stripes. The white stripes reflectorized, this panel warns drivers of approach- ing vehicles of the island's presence __________________ _____ _ 221 XlV Page Figure :37.-A raised refuge island _ 226 Figure 38.-Combination channelizing and refuge islands. The center islands extend into but not entirely across the cross walks _ 227 Figure 39.-Combination divisional, channelizing, and refug~ islands with desirable tapered shape, and overhead illumination _ 227 Figure 4O.-Channelizing islands and pavement markings at a complicated inter- section. The raised islands also scrve as refuge islands _ 228 Figure 41.-A paved median in a suburban area. The width of the second island is reduced by combined acceleration and deceleration lanes provided for vehicles making left turns to and from the divided street. _ Figure 42.-Separate lanes for left turns. The roadway is illuminated and traffic signals control movements at the intersection _ Figure 43.-At this channelized "Y" intersection, with irregular-shaped islands, traffic signals regulate the principal crossing movement. _ 23.5 Figure 44.-Separation to permit the addition of central islands was an im- portant factor in the channelization of this intersection. High-visibility curbs were used and an overhead traffic signal regulates the principal crossing movement. ___ _ - - - - _- _- - - - - __ - _ _ - _- - - - -- 241 Figure 45.-This channelized "T" intersection has stop control for crossing movements_ _____________________ _ _ 242 Figure 46.-Channelizing islands of various sizes and shapes are used at the terminals of highway grade separation ramps _ xv FOREWORD This il1anual on Uniform Traffic Control Devices for Streets and Highways in Georgia has been correlated with and conforms, as closely as conditions will allow, to the system now current and approved by the American Association of State Highway Officials, and approved as an American Standard .June 2,1, 1948. Such modifications as required to fit local requirements, and to incorporate in these specifications the most recent material accepted by this Department, have been made in this Manual. Reference is made to the detailed provisions of Act X o. 854 as they may apply to any traffic control devices described herein and as to the authority and responsibility of the Governmental units having separate jurisdictions within the State. The following eXcOI'pts from Act No. 854 of the Kovember-December 1953 Session of the General Assembly, approved .January 11, 1954, indicate the legal requirements governing all agencies or parties in the State in the installation of any traffic control device: Article III Traffic Signs, Signals, and Markings Section 31. State Highway Board to adopt manual of uniform traffic-control devices. The State Highway Board shall adopt a manual and specifications, as recommended by the Engineering Division of the State Highway Board, for a uniform system of traffic-control devices consistent with the provisions of this Act for use upon all highways "'ithin this State. Such uniform system shall correlate with and so far as possible conform to the system then current as approved by the American Association of State Highway Officials. Section 32. State Highway Board to sign all State Highways. (a) The State Highway Board shall place and maintain such traffic control devices, conforming to its manual and specifications, upon all State high\"ays including those within all municipalities and counties, as it shall deem necessary to indicate and to carry out the provisions of this Act or to regulate, warn, or guide traffic, and shall remove or direct removal of all traffic-control devices which it shall deem unnecessary. All traffic-control devices shall conform to those adopted under the authority of Section 31. 1 (b) No other authority shall place or maintain any traffic-control devices upon any State highway under the jurisdiction of the State Highway Board except by the latter's permission. (c) The dl'Sregard or disobeyance of the instructions of any official traffic-control device or signal, placed in accordance with the provisions of this Act, by the driver of a vehicle, shall be deemed as prima facie evidence of a violation of law, without requiring proof of who and by what authority such sign or device has been erected. Section 33. Local Traffic-Control Devices. (a) Local authorities in their respective jurisdictions shall place and maintain such trafficcontrol devices upon streets and roads under their jurisdiction as they may deem necessary to indicate and to carry out the provisions of this Act or local traffic ordinances or to regulate, warn, or guide traffic. All such traffic-control devices hereafter erected shall conform to the State manual and specifications. 2 Part I SIGNS A-INTRODUCTION The commonest device for controlling, safeguarding, or expediting traffic is the traffic sign. As in the case of any other type of traffic control device, signs must be used only where necessary and where justified by facts and field studies. Signs are not needed to confirm well-known or universally recognized rules of the road, such as that requiring drivers to keep to the right but they are essential where special regulations apply at specific places or at specific times only, or where traffic or road conditions require alertness. They are also needed to give information as to highway routes, directions, destinations and points of interest. Legal Authority Traffic signs shall be placed only by the authority of a public body or official having jurisdiction for the purpose of regulating, warning, or guiding traffic. Xo traffic sign or signal, or its support, shall bear any commercial advertising. It is essential that signs be installed only under public authority. Otherwise they cannot be enforced and violators will be dismissed in court. Signs placed without authority by private organizations are often poorly placed and maintained, and are not legally binding. All unofficial and nonessential signs should be removed, as they weaken the value of the necessary signs. Classification of Signs Functionally, signs are classified as follows: Regulatory Signs, giving the highway user notice of traffic regulations which apply at any given place or on a given highway, disregard of which constitutes a misdemeanor, and which would not otherwise be apparent. Warning Signs, calling attention to conditions in or adjacent to a highway or street, which may require slowing, stopping or some other maneuver. GUide Signs, showing route designations, destinations, directions, distances, points of interest, and other geographical or cultural information. 3 Excessive Use of Signs Care should be taken not to install too many signs, especially those of the Regulatory and Warning type which, if used to excess, tend to lose their autihority. A conservative use of Regulatory and Warning signs is recommended. On the other hand, a frequent display of Route Markers and Directional signs, judiciously placed, will not lessen their value. Standardization of Signs Modern highway speeds and increasingly complex intersections and interchanges require that highway signs be recognized and understood at a glance. Uniformity and simplicity in design, position and application is of the greatest importance in aiding recognition. All signs hereafter installed on any highway shall conform to the standards set forth in this manual. In situations where messages are required other than those herein provided for, the signs shall be of the same shape and color as standard signs of the same functional type. Sign Shapes The significance of sign shapes has been standardized as follows: The octagon shape shall be reserved exclusively for the Stop sign, which requires that the driver shall stop near or at the point where the sign is located before proceeding cautiously. Equilateral triangle shape shall be used exclusively for the "Yield Right-of-Way" sign, which requires the driver to yield the right-of-way to any traffic approaching intersection from right or left of the intersection roads or streets ,vhich are so close as to constitute an immediate hazard. The round shape shall be used exclusively for the advance warning of a railroad crossing. Diamond-shaped signs shall be used only to warn of special conditions either in the roadway or adjacent thereto. Regulatory and Informational signs shall be rectangular. Information signs, as a rule, are rectangles with the longer dimension horizontal. Regulatory signs are ordinarily vertical rectangles. Special shapes are also reserved for other special purposes, e. g., the shield or other characteristic shape for Route Markers on U. S. and State Highway routes, and the crossbuck for railroad crossings. If other shapes are desirable in rare cases they may be used only with the approval of the official authority having jurisdiction. 4 Color Warning signs (including the round Railroad Crossing sign) and Stop signs shall have a background of "highway yellow" with black symbols or lettering. Regulatory signs, other than the Stop sign, shall have a white background and black letters, with the exception of Parking signs which may have red or green lettering, depending on the type of restriction imposed. Guide signs shall be black and white. Route Markers and Auxiliary ::Vlarkers including Junction, Turn, and Directional :VIarkers shall have black letters or symbols on a \\'hite background. Destination, Distance and Information signs shall have black letters on a white background or, optionally, for enlarged or oversize signs, 'Yhite letters on a dark background. Dimensions The sign dimensions shown in this manual are to be regarded as the minimum standard. Increases above this minimum are permissible and desirable where investigation has shown that a large sign is needed for adequate emphasis. Hmyever, "oversize" signs should be used sparingly, in order not to weaken the effect of smaller signs. In determining whether an oversize sign installation is warranted, consideration should be given to such elements as highway speeds, the degree of hazg,rd (as appraised by a field survey of sight limitations, intersection complications, etc., or as revealed by accident records) and the competition offered by other signs, lighting, or displays. Generally the use of oversize signs cannot be prescribed on the basis of arbitrary "warrants." Each installation is a special case for study and decision. In the enlarging of signs, standard shapes and colors shall be used, and standard proportions shall be retained, so far as practicable. Symbols Where practicable, symbols are used to convey sign messages mstead of words. A simple conventional symbol like the curve arrow or the intersection diagram is instantly recognized. Symbol designs shall in all cases be essentially like those shown in this manual. Word Messages Most sign messages, particularly those of Regulatory and Informational signs, cannot adequately be conveyed by symbols. 'Word messages should be as brief as possible. Where applicable, standard wordings as shown in this manual shall be used. 5 Lettering Sign lettering shall be in clear, open capital letters of the type approved by the Joint Committee on Uniform Traffic Control Devices and its sponforing agencies as illustrated. In no case shall lettering be smaller than that shown in the sign illustrations and in manual appendix. Illumination and Reftectorization All \Varning signs, including Railroad Crossing signs, all Stop signs, all other Regulatory signs with the exception of Pedestrian signs and Urban Parking signs, and, on state highways and local roads, all Guide signs, shall be illuminated or reflectorized. Exceptions to the general rule are the School sign and similar signs which have significance only during school or daylight hours and the Men 'vVorking sign and other temporary signs, if u8ed only during daylight. Means of Illumination Illumination may be by means of: ]. A light, within or behind the sign illuminating the main message or symbol. 2. An attached or independently mounted floodlight or floodlights, directed on the face of the sign. Ordinary street or highway lighting is not regarded as meeting the requirements for sign illumination. However, such lighting can aid visibility to an appreciable degree and if present should be taken into consideration in selecting the exact points at which unreflectorizcd signs are placed. All illuminations 8hall be by white light, except that a flashing light incorporated in a sign installation shall be yellow \vhen displayed with a \Varning sign or red when displayed with a Stop sign. Means of Reftectorization Reflectorization mav be bv mean8 of: "-' oj I 1. Reflector buttons or unit:,; set into the symbol or message or 2. Reflecting coatings, either on the sign background or where a black background or panel is used, in the symbol or me8sage. All reflecting elements shall reflect white light, except that if a reflecting coating is used as a background of a colored sign it shall re- flect colored light. Sign Borders With rare exceptions, shown in the illu~trations, all signs shall have a narrow border, of the same color as the message, just in:,;ide the edge. For 24-inch signs the border shall be from :~/8 to % of an inch in width, (i set 1ll ineh from the edge, and for other sign sizes approximately in proportion, On metal :;Jgns, eorners shall be l'Ounded on a radius of ]16 im'hes, Standardization of Position S1blgh to the bottom of the sign." Overhead "ign", whether in rural or urhan areas. shall he not Ie"" than 14 feet (j inches above the road surface. \Yarning signs are generally placed in advance of t he condition to \yhich they"'call attention. Stop signs as near as praetieable to the point \yhere the stop is to be made. Other signs arc plaecd as required, in all ea"es as spceihed in the seetion of this manual dealing \yith indi\'idual signs or das"es of "igns. Standardization of Application ImpOl'tant as is standardization with respect to design and place'- ment, uniforrnit:,' of application is at least equally important. Identical conditions should always be marked \\'itlt the same type of sign". irrcspeetive of \\'here thosc particular conditions oceur. Each sign shall be displayed for onc definite and speeific pmpo"e only. Thi" manual sets forth eriteria for the application and \1,,1' of ail type" of sign", It is impo"sible, however, to set up speeifieations th:\t ean apply to e\'ery ease. Tlw proper signing of higll\yays depends to a "ery great extent on the experience and good judgment of the t'llgineer responsible for the plaeement and maintenance of signs, r rban eonditions differ from rural in respe(t to 10\yer speeds, short blocks, eongcsted traffie, parking, eompeting lights and displays, etc., and in many in"tanees signs must he different ly applied ancl loea ted, \\'here practieal, therefore. this manual set" forth separate speeifications for rural. residence, and business distrit't". Before any nc\\' higll\\'llY or any ddo\l]' 01' temporar~' route is opelled to traffie all necessary signs shall he in place, Change" in the traffic charal'teristies of a higll\\'ay nUl~' at an~' 1ime ('all for a reappraisal of local sign requiremcnts, Signs required by road eonditions 01' restrictions "hall beimmedi:1 tel:,' rem(wed \\hen those conclitions eease to exist 01' tl1(' re:-;triction,; are \\'ithdrawn, Guide signs diret'ting traffic to and on ternporar~' I'Olltes or detours shall 1)(' ],(moved \\'hen no longer applieablE'. Erection ~ ormally signs should he individually erected on separate po"ts, except \\'here one ,;ill:n sHpplements another, or \\'here route OJ' direct ional signs must be groHpeel. T\\'() signs for different purposes ,;boule! not llP placed doseI' together than 100 feet along the high\y;)\' if it ean be reasonably avoided, Exception" to this rule are sonwt imes necessary, particularly where space is limited. but the pl'iJl('iplc is sound. Two signs closely adjacent are difficult to read at high speed on two-lane roadways. This general role applies to signs facing in opposite direction,;, which to minimize distn-action, should not be placed immediately opposite each other on each side of the roadway. 8 Materials Metal treated with a rust-resistant coating shall be used for permanent signs. Wooden boards may be used fot temporary signs for special occasions or emergencies. Such other materials as may have been accepted by the State Highway Department may be used when supplemental provisions for this manual are properly approved to that effect. K on-corrosive bolts, screws, and washers shall be used for attaching permanent signs to their supports, to avoid discoloration. Sign Posts and Their Foundations Sign posts and their foundations shall be so constructed as to hold signs rigidly in a proper and permanent position, and prevent them from s\yaying in the wind, or from being turned or otherwise displaced by children or irresponsible persons. . A portable or remoyable type of mounting is desirable for ::Vlen Working, School, and similar signs used temporarily or intermittently. Such a mounting should be heavy enough not to turn over in the wind, and its base should not be appreciably ,,'ider than the sign. Maintenance All traffic signs shall be kept in proper position, clean and legible at all times. Damaged signs shall be replaced immediately. Signs poorly maintained lose their authority as traffic control de- \ices. Damaged, defaced, or dirty signs are ineffective and discredit the agency responsible for them. To insure adequate maintenance a suitable schedule for inspection, cleaning, and replacement of signs should be established. All signs should he inspected regularly and any that are defective should be deaned, touched up, or replaced and taken in for repair and refinishing or 8crapping. Employees of the Highway Department, Traffic Police, State Patrol and other governmental employees whose duties require that they travel on the highways should be instructed to report any damaged or obscured sign at once. Special care should be taken to see that weeds, shrubbery, construction materials. and snow are not allowed to obscure the face of any signs. HEIGHT 8 LATERAL LOCATION OF SIGNS STOP SIGN RURAL DISTRICT WARNING SIGN RURAL DISTRICT '- ..........." 4.... . ,;1010' _ REGULATORY SIGN BUSINE SS OR RESIDENCE DISTRICT .~:":::" : .... -~..' .: ~:. . . ' ! ' . :.:.:.: . .. REGULATORY SIGN BUSINESS OR RESIDENCE DISTRICT :":, lJ TURN MARKING ASSEMBLY BUSINESS DISTRICT liTh [BJ NO"t I LESS 1 HAN " 10 .4. ~, ," ",', . ' , , 0 '." '' ,' '''''' ..... ,.;, CONFIRMATION ROUTE MARKERS BUSINESS OR RESIDENCE DISTRICT LOCATION OF SIGNS IJUNCTION I ~ Unl.cllFir ~! JUNCTiON ASSEMBLY RURAL DISTRICT ~ r iI I l >-, I ,'" j ".-------1 sl \:{:<;,o;~"~'c-=n -_:l C, TURN MARKING ASSEMBLY BUSINESS OR RESIDENCE DISTRICT --;:)j:Q;(1:9:1;"~T.H~O=M=AS.T=O=N-;-------------~ ATLANTA-+ OVERHEAD DESTINATION SIGN II B-REGULATORY SIGNS Application of Regulatory Signs Regulat0J] signs shall be used to inform highway users of certain laws and regulations enacted to promote safety and convenience upon the streets and highways, the violation of which would constitute a misdemeanor. These signs are essential to indicate the existence of legal requirements that would not otherwise be apparent. Great care must be exercised to see that they are erected wherever needed to fulfill this purpose, but unnecessary mandates should be avoided. Regulatory signs shall be erected at those locations where the regulations apply and shall be mounted so as to be easily visible to the motorists whose actions they are to govern. The message on the signs shall clearly indicate the requirements imposed by the regulation. Signs which have been erected but which are no longer applicable shall be removed. By establishing uniform standards of application, location, size, shape, color and dimensions for different types of Regulatory signs the motorist can always recognize them quickly and be governed accordingly. Classification of Regulatory Signs Regulatory signs are classified in the following groups: 1. Stop series. 2. Yield Right-of-Way series. 3. Speed series. 4. Movement series. (a) Turning. (b) Signal. (c) Alinement. (d) Exclusion. (e) One-way. 5. Parking series. (a) Prohibition. (b) Restriction. 6. Pedestrian series. 7. Miscellaneous series. Design of Regulatory Signs With few f:1xceptions, Rlgulatory signs are rectangular in shape with the longer dimension vertical. With the exception of the Stop sign and the Parking signs, they are white, with black lettering and border. Stop signs and Yield Right-of-Way signs are "highway .yellow" with black lettering and border, while Parking signs may be white with red or green lettering and border as specified. ' 12 Minimum dimensions are p;iven for each sign here specified. Where conditions require greater visibility, or where the required message cannot be accommodated on a smaller area, larp;er signs may be used, in which case all dimensions shall be increased in proportion. Other Regulatory Signs l I . Regulatory signs other than those specified ab~Ye may be required to aid the enforcement of other laws or regulations. They should be of adequate size, and designed with black letterillg on. a white back- ground, on rectangular plates with the 10ngeJ;., dimension vertical. They shoul~ be mounted in accordance with the general requirements for sign position. Typical miscellaneous Regulatory signs are Tractors With Lugs Prohibited, Road Limit 10 Tons, Wet Paint, Do :\ot Cross Line, No Dumping Allo\\wl, X0 Hitch Hiking and X 0 Fishing From Bridge. The uses for such signs are sufficiently obvious to require no detailed specifications. Stop Sign R-l It is commonly provided by law that State and local authorities, \,"ith reference to high\yays under their respectin=' jurisdictions, may designate through highways and erect Stop sip;ns at specified entrances thereto, or may designate any intersection as a stop intersection and erect like signs at one or more entrances to such interseetion. Design of Stop Signs ,- . "ONing to the importance of Stop signs they are given a dlstinctive shape (octagon) and color (red). The red color is consistent with the accepted use of a red light as a Stop signal and of the color red as a special warning of danger. The Stop sign shall be octangonal in shape, shall have a red background, and shall carry the word STOP in white letters at least onethird the height of the sign. The Stop sign with yellow background and black lettering now in position may remain until replacement or refinishing is required, with full legal status. All Stop signs erecteti hereafter will have a red background, and white letters." 13 , ill tl\(, it b"elll'e of :IIlY ('( lIldu"i q' l'Y idel\('(' "hu\\'i ll~ itt 0 he h',;,; erfe(' ti\ t hall the yellO\\', 1)nfln"tnr;",tion or T1lnminatiol1 "All Stop signs shall be illuminated or ~eflectorized at least in the lettering. =llumination may be by floodlight or by fixed white lIght in the letters. ;eflectorization may be by white or clear t~flecting units or reflecting coating in the :etters, with or without a red reflecting ~oating on the background. In addition to :~ulcahshiilnlgumreidnastiiognnaol,r reflectorization in operation both a by day end by night, may be incorporated in the face 'Jf the sign or placed just abOve it." i . .l.lll..'Cl,--\.\ .. \I\'11 , , . applicatiull of tIl(' 1l., 15 j-L M P I"t FIGURE 8 II 38 should be used with symbol or legend enlarged approximately in proportion to outside dimensions. (The dimensions are measured along' the side of the diamond, not diagonally.) Location of Warning Signs Since Warning signs are placed primarily f~)I' the protection of the driver who is unacquainted with the roads, it is very important that thought and care be given to their location and erection. Although it is pecified herein at what distances the signs shall be placed in ad- yance of the hazards warned against, there will be many instances where physical conditions 'will require different distances. Trial runs hould be made by day and by night to determine the most effective location and erection characteristics for each installation. In cities, II"here speeds are relatively low, Viarning signs should usually be placed nearer to the points of hazard than on rural hig!J.wa s. "In rural and residence districts where no parking occurs, Warning signs shall be erected not less than 6 feet nor more than 10 feet from the edge of the pavement or ... .,' traveled roadway, with the lowest edge of the sign not less than 5 feet above the roadway, except as hereafter indicated. In any location where they will obstruct sidewalks or pedestrian paths, however, they should be mounted at a height of not less than 7 feet to the bottom of the sign. In residence and bUSIness districts wnere parki n9 is frequent, theY" s!1all be so set that the bottom of the sign is not less than 7 feet above th~ top of the curb and lefthand edge not less than one foot back from the outside edge of the curb.'" 'ither to the right or left shall tw u: I to mark a curve in the lin ment of the highway. . II 'u['\,e sign shall be reft torized. ThE' 'un' 'Ign hall be erect- not I." than 300 feet nor m than 750 feet in advance th h ginning of the curve W-l ' 24" x 24" Thhfrobm'(ogtItltohmehalO dlfgbeteheomf o.Itguhl1ne,tepadanvdneomntoeltnetsl.essstThtahhnea 6 feet from n 6 feet nor S'Jgn should the pavem .more than be erected ent 10 at 39 REVERSE CURVE SIGNS INSTALLATIONS TYPICAL . ,. ~. W0 3 40 '" P Ii I W-28 -10 such height in excess of the llliillll1Uill requirements to be the most effective at the greatest distance. On curves having a safe driving speed of less than 60 miles per hour the Advisory peed sign (W-28) should be mounted below the CLuTe ign and shall show the safe peed that the curve can-be dri,'en. See fig, 8. TURN SIGN W-2 The Turn sign (W-2) 36" x 36" showing an arrow bent at a 90 angle either to the right or I ft shall be used to mark a right-angle turn in the alinement of the high\yay. See fig. 8. All Turn ign shall be reA torized. The Turn sign shall be erected not Ie than 200 feet nor more than 7 0 feet in advance of the turn. It hall be mounted so that th b ttom of the sign will be not Ie than 6 feet above the puyement surface, and not les thun 6 feet nor more than 10 f t fr m the edge of the pavem nt. The .\ hoi ory Speed sign (W:! I 'hull be mounted below the Turn .ign and shall how the fc sp<, d that the turn can be drivE-no W-2 36" x 36" 'ER E RVE SIG W-3 Th HE-verse Cuwe sign (W-3) _'I" .' '21" -hall be used where t\\ 0 ('IlrWs in oppo ite directions purat d by a tangent of than -l00 f et. It shall show n rrow ('un' d twice in oppo- I di~tion" 11 Htvcrs(' '\I n' ..igns shall ft toriz('(l. W-3 24" x 24" 41 W-4 36" x 36" 42 The sign shall be erected not less than 300 feet nor more than ~50 feet in advance of the beginning of the first curve. It hall be mounted not Ie s than 6 feet from the bottom of the sign to the pavement sur face, and not less than 6 feet nor more than 10 feet from the edge of the pavement. On reverse curves having a safe driving speed of less than 60 mile per hour the Advisory peed sign (W-2) shall be mounted below the sign and shall show the safe speed that the curves can be driven. See fig. 9. REVERSE TURN SIGN W-4 The Reverse Turn sign (W-4) ize 36" x 36" shall be used where two turns in opposite directions are eparated by a tangent of less than 400 feet. It hall show an arrow bent at 90 angles in opposite directions. All Reverse Turn signs ball be reflectorized. The sign shall be erected not less than 300 feet nor more than 750 feet in advance of the turn. It shall be mounted not I than 6 feet from the bottom of the ign to the pavement urface, and not less than 6 feet nor more than 10 feet from the edge of the pavement. The Advisory Speed sign (\\'28) shall be mounted bela\\' t Reverse Turn sign and sb show the safe speed that th turn can be driven. W-IA 48" x 48" W-2A 48" x 48" PPLEME TAL CURVE AND TURN SIGNS W-IA, W-2A. W-3A AND W-4A ur... and Turn igns (W-IA, W-2A, W-3A and W--4A) 48" x 48" tx- uMe(,tion of this sign, In some I'll: it may be used for em- W....{; 36" x 36" 45 pha is where there is POor observance of the Stop sign. The Stop Ahead sign shall be erected not less than 350 feet nor more than 750 feet in ad. vance of the Stop sign and in accordance with the general specifications for the placement of Warning signs. In cities it may be necessary to erect the sign less than 350 feet in ad. vance of the Stop sign in order to have it within the same blOCk. See figs. 2 and 15. SIGNAL AHEAD SIGN W-7 The Signal Ahead sign shall be used at any rural signalized intersection where the signal is not visible for a distance of 400 feet in advance of the intersection, or at any signalized interection where the prevailing approach speeds or conditions of visibility are such as to justify an advance warning. se of the ign i \Yarranted where horizontal or vertical curves limit the sight distance on the approach to traffic ig- W-7 36" x 36" 48" x 48" nals, or where lights or illuminated signs at the intersection may distract the driver's atten- tion from the signal. The ign hall be erected not Jess than 400 feet nor more than 750 feet in advance of the intersection and in accordance with the general specifications for the placement of Warning signs. In cities it may be necessary to erect the sign Ie s than 400 feet from the ignal in order to have it within the same block. 46 HILL SIGN W-8 'here f ty demands a det of the grade in intermedin or (0'" gear, the Hill ign rna\" be us d. j"lH' Hill ign hall be located Dot 1('0 . than 300 feet nor more than i50 feet in ad"ance of the inning of that part of the dowl\~radc "'here conditions require 11 r duct ion of speed f?r fl,t\.. It hall be erected III s('l'o;dllncc with the general JX'l'ilication for the placement of Warning igns. B MP SIGN W-9 Th Bump sign shall be used to ~i\' "'arning of sharp rise in the pr fil of the road that i ,uffieicnlly abrupt to create a hllzllrdou condition, to cause l'(IIl..id rable di comfort to pas. 0l':el", to cau e a shifting of the Cllrgo, or to deflect a vehic'(r from it true course when ('rcl:',('d at peeds 25 pel' cent gr ater than the normal driving pl'l'tl f r that ection of road. The Bump sign shall be located not les' than 300 feet nor more than 7-0 feet in advance of the hazard and hall be erected in :u'('ordance with the general p cifications of the placement of Warning signs. DIP SIGN W-IO 1'h Dip ign shall be used to h'c warning of any sharp depre i n in profile that is sufficiently abrupt to create hazards of the type described in connection wi.th ~he Bump sign (W-9). Th DIp Ign shall be applicable and u d'III the same manner as the Bump sign. W-8 36" x 36" W-9 36" x 36" W-l0 36" x 36" 47 TYPICAL SIGN INSTALLATIONS TRANSITION FROM Z LANE TO 4 LANE HIGHWAY rI!i I iI I TIT FIGURE 10 48 TIU' USC' of the Dip sign ~t a ort .'tr teh or depressed ahn'\ement that may, momentan y bl'd(' 11 m nlIl';my if the 'dth p('rmit. It should be located not than 300 feet nor more than 750 feet ~. alh'ane f the section being treated approach of the roadway affected. at MEN WORKING SIGN W-21 The ::-'1 n Working sign shall be used primarily f r the protection of men workin on the road in the path of traffic, or for the protccLion of traffic when the natun' of th(' work it elf is such as to create hazard . . Il'n Working sign shall be placed approximately 350 feet on each ide of the tion where men are at work. The sign hall he mounted on sub tantial portable apport , not easily knocked over or blown down and placed in the center of the road 11/11 ..~ the width of pa\"ement, poor shouldl'rs. or other conditions make thi inad\i.. hie, in which case they shall be placed adjac'ent t the roadway on the shoulder IIf th r ad. They hall be in place as long . there arc men working on the road, or thl'rc i.. any piece of equipment in the roadway, ct ., but shall not be left up during !hc lunch p riod or at night or on holidays If the road i free from hazard at that time. .\n 1 " x 18" red flag should be di played ahove ach ign and if used at night a red lant rn or bomb torch should be placed I . id it. The signs should be moved forward a. any work progresses so that there W-20 24" x 24" W-21 24" x 24" 57 W-22 24" x 24" W-23 24" x 24" is at no time a distance of more than 1.000 feet between the sign and the wOl'kmen.' SOFT SHOULDERS SIGN W-22 The Soft Shoulder sign shall be used where soft shoulders present a hazard t vehicles that may get off the pavement This sign will usually be warranted o~ newly seeded shoulder Ol' on roadway where shoulder are dangerou ly 150ft due to weather conditions. The ign should be removed when the hazard no longer exist Soft Shoulder signs shall be erected i,; accordance with the general pecification for the placement of Warning sign. One sign shall be placed at or near the beginning of the soft shoulder conditions and other signs shall be placed at intervals through. out the length of the road where the con. dition exi t . SLIPPERY WHEN WET SIGN W-23 The Slippery When Wet sign shall be u ed to warn traffic of an extraordinarilv i lippery Ol1dition when the pavement wet. The use of this ign should be kept to an absolute minimum, and upon correction of the slippery condition the sign should be removed. The sign shall be erected in accordance with the general specifications for the placement of Warning signs. On rural highway it should be located 500 feet in advance of the beginning of the slippery section and at not greater than 2-mile intervals on long sections of uch pavement. In urban districts the e distances should be greatly reduced. DOUBLE-ARROW SIG W-24 The Double Arrow sign showing a double-headed horizontal arrJW shall be used at loading and refuge island, traffic islands with curbs more than 3 inches high, and obstructions in the roadway, where traf fic i permitted to pass either side of the island or obstruction. 58 . hould normally be mounted at a height of 4 feet to the Igfn th ign. On an island it should be mounted at the ap- m d r a closeO thereto as pra' ctlCable. hhoenuld0 be mounted. on t.he face f 0, or J. ust m. f r~nt f 0 a 'pI.er or I I ob truction, m whlCh case the standard strIpe markmgs on rl.l.lr~gtruttion should be d"Iscontmued to Ieave a 3-'mch space around OU" . ut 'id of the sIgn. o u e an obstruction in the line of traffic is likely to be obscured mbo' uvn(t.A'a_h.,.I1..(-Ide ir, ecatlysecaobnodvesitghne of the same design should ordinarily be standard sign with its lowest edge 7 feet ho\'(' th pavement. . . n('rt' traffic must keep to the rIght of the Island or other obstruc- . the Keep Right Regulatory sign (R-20) should be used. t10Tnhe Double Arrow S.ign 48" x 48" may be used at T m. tersections. W-24 48" x 48" RAILROAD ADVANCE WARNING SIGN W-25 Recau e railroad grade crossings present a :[X'eial type of extreme hazard, Warning i~I' of distinctive designs are prescribed for them. The Railroad Advance Warning sign 'hall be ('arrym. g a yellow disk 30 a "Crossbuck" iXnchaensdinthdeiamleettteerrs' "RR" in black. Every Railroad Advance Warning sign shall be reflectorized. W-25 30" diameter 59 The e;ign e;hall be ue;rd in advance of en)rv railroad ('I'oe;e;illO' . . ,'" if C'\ '('11 prote(ted by e;lgnale;, gates, or flagman. exeept III the' l()ll()wi!Io' . e;t,an('ps: " Ill- 1. .\t a minor siding or spur \\'hich is iuf'requpntly ue;('d and \\,hl"b I.e;'~gual'( Ic'c 'I \\'lH'n'muse 1ly a mem1)pI' 0 f' t l w tr'am ('1'('\\. (I ,) I n the hue;inpss distriet of the large cities \Y!ll'l'(' tlte ('rossings arp fully protected all(l tlw phye;ieal condition" an ~llch th ('WII a partially ef'fecti\'e display of the e;ign i" im!l()e;e;iblc. at In l'\Iral distriets this sign shall Ilormally br placed 7,-)() f,'p! in ad. \'ance of the ('I'oe;e;ing, although local conditions, s\[('h as grad,'s. curves and limitpd Yi"ibility may makc' e;ome intermediate die;taJl"(' 1)('t\H'e~ :300 feet and 7;')0 feet more sati"factory. In any cae;e till' die;tall('e shall he great rnough to permit \'ehi('lee; at prentiling sprecls to 1)(' brought to a complC'tp stop before the (Tossing is reached. TIIP e;igll e;hall he C'rected on the right-hand side of the roachmy in a('('cmlan('(' i"ith the general specifications for the pJacempnt of 'Waming signs. In re:,;idence or business districts \\'here 1m\' sjweds arc' jln'\'alent the sign may he placed a minimum distance of 100 feet from lIw ('l'OSs~ ing. If there i:,; a street intersection within 100 fpet, an addi! ional siglI or signs should he so placed as to wam traffic approaehing t II(' cross- ing from each intersected street. Railroad :\ch'anee \Varning signe; are usually off the rail mad right. of-way and are properly the n'e;pOlI"ibility of the hi!!;Il\ray 'l\Itltorities. RAILROAD CROSSBUCK SIGN W -26 Tlll' de:-;ign of the commonly u:,;ed Hailroad Cros:-;buck, \\'it It .\uxil. iary sign :-;howing ttl(' number of tra(ks. has been e;tandardi;r,c'd by the .Joint Committee OJI Grade Crossing Protection of tlll' A"e;(wiaiion of .~nwriulll Hailroad:,;. The C'ros:-;blwk sign ie; furni:-;hed and illstalled by the railroad company, and i:-; usually 10('ated OIl tlw railroad rightof-way to :-;hm\' the loc'ation of the tnu'ks and the numlwr of tracks. Detail:,; are shcmn in Bulletin ~ o. :3, Railroad [fiUll/my Grade ('rossing Protection . .\ssociatioll of American Railroade;. The ('roe;sbll('k shall be \\'hite \\'ith \\'ords "I{ailroad Croe;"illg" in black lettering. If there are two or more tra('b, indllding "itlings. the nurn)wr of track:-; e;hall be indi('atec! on an Allxiliar~ sign of ill\'erted "1''' shape mounted below the (ro"e;IHlck. The di:-;tallce that e;llOuld he a:,;sumed to :-;eparate tracks hefon> an additional Crossing "ign is eonsidered i:,; 100 feet, Ilnb.;e; local ('clllditione; require otheI'\Yie;('. The practiee in :-;ome loealitie:-; of placing the Hailroad (')'(N:!mck sign all a pedestal or island in the ('enter of the roadway ie; e;ll'Ongly disapprm'ed. The sign shall 1)(' erected 011 the right-haml side of the roadway on eaeb approach to the ('ro:-;sing, not more than l;j fc(,t from the center line of the nearest track and not ke;s than () feet no)' more GO 10 f('Ct from the edge of :he pavement. The height hould be \" htI.:'amI)<.l~" the level I)" \'aried c of the highway to the center of as reqUI.red by locIa dcon"ItlOns. the crossbuck, W-26 9"' x 48"' 9"' x 60"' RO ING SIGNS W-27 Th ing signs, indicating type of crossings, as hool rossing, Truck Cros ing, Ped .trian rossing, Cattle "ing, Deer Crossing, shall be u I at hazardou crossing of th typ indicated. The sign mayor may not be of a tempo- rary 01' ea onal nature, but ould b r moved if and when the hazardou condition ar tt'mlinated. In mral area the sign shall be located n LIes than 300 feet nor mol' than 750 feet from th era ing. In urban areas a hort I' di tance will usually be d~.irabl. The sign shall be <>r('('ted in accordance with the <>nf'ral . pecification for the phwrm nt of Warning signs. In .muny in 'Lance it may be de.lrabl t.o define the crossing hy pm-cmenL markings. W-27 36"' x 36" 61 W-28 18" x 18" W-29 24" x 24" 62 ADVISORY SPEED SIGN W-28 The Advisory Speed sign i s~all plate 18" x 18" square' with the message "- M.P.II ,: in black on a yello.w background. It may be used m conjunctio with any standard yellow Warn~ ing sign to indicate the maxi. mum "safe speed" around a curve or through a hazardou location. When used, it hall be mounted immediately below the standard Warning sign and on the same post, with its lower edge not less than 4 feet abo\"e the pavement. The speed shown shall be in multiple' of 5 miles. In no case shall such a sign be erected until the afe speed has been determined by accepted traffic engineering procedures and officially approved. Because changes in surface characteristics, sight distance, etc., may alter the safe speed, each location should be periodically rechecked and the Speed sign corrected if necessary, as shown in figures 8 and 9. CATTLE CROSSING SIGN W-29 The Cattle Crossing sign is to be placed 300 to 500 feet in advance of any point where cattle are regularly driven across the highway. For maximum effectiveness, this sign should be a portable sign. When responsible persons are not available to place and remove this sign on each crossing of cattle, permanent signs should be installed. This sign is not to be reftectorized. DETOUR SIGNS TYPICAL INSTALLATIONS ROAD CLOSED TO TRA FFIC I L------:---~.:-.--------""--~--,.~--~ -_.-J~ LOCAL TRAFFIC MAINTAINED FIGURE 13 W-30 36" x 36" W-31 36" x 36" WATCH FOR CATTLE SIGN W-30 The Watch for Cattle sign is to be reflectol'ized and placed along those sections of highway where fencing is not provided to keep cattle from the right-ofway. The e sign should be placed at sufficient intervals wherever such conditions exist. DETOUR AHEAD SIGN W-31 The Detour Ahead ign shall be used as advance warning of the approach to a point in the highway that the traffic is diverted from the route. The sign shall be erected not less than 100 feet from the intersecting detour and shall be followed by standard Route and Directional Markers as shown in fig. 13. On highways where speeds are high an additional Detour Ahead ign may be erected 1,000 feet farther in advance for added protection. Placemen t shall be in accordance with specifications a outlined in this manual. DRAWBRIDGE AHEAD SIGN W-32 The Draw Bridge Ahead sign hall be used a an advance warrun of the approach to a draw bridge and located not less than 500 feet nor more than 1,000 feet from the bridge. The ign shall be 4 " x 48" and shall be reflectorized. Coloring and placement hall comply with specifications as outlined in this manual. 64 W-32 48" x 48" DRAW BRIDGE SIGN W-33 The Draw Bridge sign shall be reflectorized, placed at the extreme I'nd of the draw bridge preceding protective gates and placement hall comply with general specifications as outlined in this manual. Th ign shall be located not over 100 feet in advance of the bridge Oil hath sides facing approaching traffic. It shall be mounted not 1(':' than 4 feet above the pavement. W-33 48" x 48" 65 W-34 24" x 24" W-35 24" x 24" 66 CROSS ROAD SIGN W-34 The Cross Road tical cross symbol, sign, shall showing the be erected ~'er. through highway of a cross road. to I tisnduisceateshtohueldprebeennele!. stricted to intersections with road t~e. are improved to such an extent that there is likely to be a fairly large vOlu~t of traffic entering or crossing the through route and where unusual features, 'uch as poor sight distance or obscured en. trances, make it advisable that the inter_ section be called to the motorist's atten. tion. It should not ordinarily be u ed where Junction signs or Turn Marke are present. Too frequent use of the Cross Road sign should be avoided. More complex intersections, or oblique crossings, may be shown by appropriate diagrams. If there is a considerable difference in the importance of the intersecting road" the more important route should be shown by a heavier line in the diagram. Since this requires the stocking of se\,eral different designs, however, and since a turn in a numbered route is shown by Route Markers, the use of different widths of line is not mandatory. The Cross Road sign shall be erected not less than 300 feet nor more than 750 feet in advance of the intersection, and in accordance with general specification for the placement of warning signs. SIDE ROAD SIGN W-35 The Side Road sign, showing a sideroad symbol, either left or right, and a an angle of either 90 or 45 degrees, shall be used in advance of a side-road intersection according to the same warrant and specifications as set forth for the Cross Road sign (W-34). T YMBOL SIGN W-36 T ymbol ign shall .be used. to traffic approaching a T llltersectlOn road that forms the stem of the 1. ;0 o wh rc traffic must make a turn r th right or to the left. The all not be used on an approach traffic i required to stop before 'ng the intersection, ~or at a T tion that i channelIzed by traf- oland" nor, generally, where J unciR'I' or Turn Markers are pr~sent. I' lati\'e importance of the llltering road hould be shown by differ- n 'idth T of line. ymbol sign shall be erected I . than 350 feet nor more than 500 I in advance of the intersection, and an IK'cordanc with the general specifica1 for the placement of warning signs. I may b de irable to place an addition- l' :'ymbol ign at the head of the T di tly in line with approaching traffic. Y YMBOL SIGN W-37 Tht' Y ym bol sign shall be u ed to rn m tori t approaching a Y intertion on th road that forms the tem tht' Y. It hall not be used at a Y int -tion that is chatmelized by traffic i land, nor, generally, where Junction 'ign' or Turn Markers are pre ent. Th(' I' lativ importance of the intertinll: road should be'shown by diffeI'nt width, of line. Th Y ymbol sign shall be erected not 1(' than 350 feet nor more than 500 f t in advance of the intersection and ) t~ accordance with the general specificatIOn for th placement of warning signs. It may be de irable to erect an additionI Y int l' ection sign at the fork of the Y dir eUy in line with approaching raffie. W-36 24" x 24" W-37 24" x 24" 67 BUSINESS DISTRICT W-38 18" x 12" BUSINESS DISTRICT W-38 This sign shall be 18 inches by 12 inches in size, with black letters on a white background. These signs will be no wider than the Speed Limit signs upon which they are mounted. These signs will be erected on top of the Speed Limit signs only after authorized by the Director of Public Safety in business districts. RESIDENCE DISTRICT W-39 18" x 12" RESIDENCE DISTRICT W-39 This sign shall be 18 inches by 12 inches in size with black letters and a white background. These signs will be no wider than the Speed Limit signs upon which they are mounted. These signs will be mounted on top of Speed Limit signs only after authorized by Director of Public Safety in residential districts. W-40 24" x 36" ROADSIDE PARK W-40 This sign shall be 24 inches by 36 inches with white letters on green background. These signs will not be reflectorized. They shall be mounted at right angle to the pavement facing approaching traffic, and not less than 6 feet nor more than 10 feet from the edge of pavement. They shall be erect- ed one mile and >i mile on each side of entrance with mileage posted on bottom of sign, and the third shall be at the entrance of the roadside park. These signs will only be erected for roadside parks built and maintained by the State Highway Department. All other roadside park signs will be erected off of State Highway right-of-way. OTHER WARNING SIGNS Warning signs other than those specified above may be required under special conditions. They should in every case conform with the general specifications for shape, color and placement of Warning signs as set forth in this manual. Typical miscellaneous Warning signs are Playground, Bridle Path, Hospital, Crosswalk, Tunnel, Uneven Tracks, Rough Road, High Water, Range Cattle, Factory Entrance and Slides. The applications of such signs are sufficiently apparent as to require no detailed specifications. 68 DGUIDE SIGNS pon of Guide Signs "I.Lr.oI_._ilJu.'IA(1.I-'tdueU .TPhe s,Ign Hou t e s.'I\,'H',IIe'khD,Ie,'r~,e,'lcnod.n,s"AIduexrl,eh,da,rJ'vIl three maJor :\Iarkel's. groups: De:;tination and Distance slgn", Informat ion sign"" . , " " " ,. 'I'k other typcs oj slgnl'J, GlIlde l'Jlgni'l do not lose effedlveness hy l nI e frequen t I 1'M" . ,Yhcn there is any IIonI)t a" to t1te altld 1)(' mO'lIItPd ;10' 1>llllilWd for Ilin'diolla! .\1:lrK('r", M--12A 13" x 10" TEMPORARY MARKER M 15 TIll' Tpm p"rary\[ aller "hnll ,'a1TI' Ilw \\1 'I'd "Tt'mporar~'" ill hl;wk leI tel''' Oil n Ilhitl' pialI' 21":\ !I" ill "iz(', It "Iudi 1)(' mO'lll1ed imnll'dintp!y al,()\'(' a I((>lill' \[nrKer (\1 2, \[ ;.\) 10 illdi- ITEMPORARY I M-lS 24'" x 9' (';I\(' t'it her: (:11 ,\ J'Illlte t('mpor:trily de"igllat,'d 1111t llt,t illll']lC!I,d a" ;I ]H'rlllllatel\' :illl'l'!' :1 Houl(' .\lal'\.:('l' (.\1 :!, .\1 :ri 10 d";~lIate ~I rou\(' Il'hil'll hl'alll'lle" fl'l'lll Ill(' I'('g:u!:l I IlIlm- l)(,l'l'd mill!' lh]"IIIg:h a (it,\". hy-p:I"".(',,; IIii' ('it\, alld )'l'joill" th(' )'l'g:ul:11' Ilulllh(,l'l,II Ii I\'hite plal(' :!-II! x !II! III "iw, It "Iwll h(' llHI!lllled im. llwdiat('ly ah(ll'\' a l(oUl(' .\Iark(,1' (\1 :!. .\1-3) to d('"ig:llale all auxiliary I'OUll' 11lli'!1 ill'alll'hes fJ'()1ll a 1'('g:\11:11' 1\\1mh(']'('<1 l'Illl1(' tll]oll!lh a I'ity to dil'(,('\ traMi(, thr()ug:h til(' \l\billt'"'' portion of ill(' ('it~. TIll' l)\1"ill('"'' I{out(, ~\",,('mhly "hall lw u,,('d in th(' "alll(' nWIlllPr as :l regular \(O\lt(, .\[arkt'1' and "hall \)(> lo('atl'd alld ('\'('('l,'d ill a('('ord ,lIl('e wilh lhl' ';:l\11l' Sjw('iti('alioll". NORTH M-19 24" x 9" CARDINAL DIRECTION MARKER M-19 Thl' Cardinal Din,(,tion .\Iark('1' ,..;h:dl ('any the wonb "\:0I't1l, 80\1th, 1':a"t O!' \\(',1" in black: Jelll'!''' on white plate 24" x \11/. It may rH' monnted dire('t h :Iho\'e Haute! l .\Iarker (:\12 0]' :\[-:3) to illdi:':ll" the genertl1 dire(,tioll of tile routl's. Tt should II(' u~ed onl1' iG where motori,;t,;. ill t nlll,;t'crrilig from OIiC rout C to allothcr. might be eOllfu;;ed a;; to thc dirc('(ioll ill Iyhidl lh(' illtcr;;('c!cd routc 1l'(lIdd take lIl<'m, :-\('(' fig;;, I L 1.-) alld IS, SECONDARY DESTI~ATIO;\i MARKER M lOA The :-\ccolldary I )C,;1 illat iO!1 ~Iarker (~I Il!.\! ;;Iwll 1)(' :3(;" '\ Ii" ill ,..;ize \I'ith 011(' I'il.\' Ilall](' :llId mile:I,!2:I' ill hlack I('j 11'1''; O!I Ilhit(' aJ'l'II\\ alld ,;hall hc 1'('- 1!e('lllrize(I, (CAMAK M-l0A 36" x 6" 15 ] I~FORMATION SIG~S IlIf()J'mat ilill ..;igll;; aI'(' \'al'i~lhlc ill ..;ize ~llld ill ml'..;..;agc Tlwy illl'ludl' "lwh illf()J'll1:1t ilill a;; II a111('."; oj' I'i\'('r,..; C!'o";";I'd, ('it,\', \'illagl'. 01' t011'11 limit", ('OUllt,l' lillc;;. ;;tat(, lillc..;. ('In'alioll";, ('1(', IlIfol'lnatioli ";lgll"; "hall I,(, hmiwlltal l'('I'tallgl('", Thc,\' ..;hall ha\'(' h];l('k Ictt(,l'illg Otl a white I,a('kgrlllt!ld, 'I'll<' ,;ize of I('tlel'ittg u;;('d "hould hI' ;;I[('h a" to I!in' ad('qllall' I('gihility fol' tIl<' purpo,;c to 1)(' ;;cl'\'('d. :-lilll'(' thc,,(' "igll'; an' 1'01' illf(\rmalioll plll'pO';(';;. alld do 1I0t ordillarily "I']'\'C to I'('gu- !atl'. Ill' guidI' lr;tfli(' {l'XI'Cpt pcrhap,; ilidin'ltly ill t hc ('a"e of ('it.\, lim- it:,. ('tl.1 Ill<' Il('cd for 1Il1ifol'lnity itl dc,;ig!1 to ill';lll'C autollwtic 1'('. ;;Pllll;;p i;; IIllt ~t111Igclhcl' (,,;,,clltia!. TIl<'Y ;;lwuJd. hOI\'('\'CI'. Ill' of ,..;talldard ;;happ alld ('1l11 )J', III rural di,;tril'1...;. tIl<' IIIfol'lnatiOll ;;igll'; "holiid Ill'dillarily 1)(' mOllltt- cd fwm Ii til III 1'('1'\ from thc pa\'('n1l'llt cdgl'. alld \Iith till' hottom 1I0t !f'l',."; thall Ii ft'('1 ;Iho\'(' thc pa\'('Il1l'II1. The lJ:UlW of a ri\'e]' IlW,I' 1)(' O1Olll1tpfu'k from the ('urh, STATE LINE (INFORMATION 1) 72" X 36" Thc ~tatc LillI' "igtt ,..;hall bc phH'ed at lhe ,;tatc houndary lillc Oil all ldt'atc and 1'. ~. hig}I\\'a' \',;, alld. 011 ';l\(h I' 'OUII!Y hig"h\y.ay,; a,; ma.y 1)(' Ift'('t('(! hy t IH' allt ll()rit ic;; of ('oullti(',; ",hiph border ot!wr ,;laU',;. 71 GEORGIA STATE LINE 1-1 72" x 36" CITY LIMIT SIGN (INFORMATION-2) The City Limit sign shall be 24 inches high by variable !<'llgth (depending 011 length of city's name) using 8- and -!-indl letters. The sign shall be rcfleetorized and placed along state and '-. S. high. ways at city limit line_ ATLANTA CITY LIMIT 1-2 24" x Variable FULTON COUNTY 1--3 24" x Variable COUNTY LINE SIGN (IN FORMA. . TION3) I The COllnty Line sign shall be 24 inches high by variablP length (cleo; pending on length of COllllty name)' using letters (j inches h i g h . : The 8ign shall he rcfl(,(,t orized an~ placed along 8t ate and '-. ;-;. high,YaYl, at the cOlmty line. I I ABERDEEN I. I 4 18" x Variable UNINCORPORATED VILLAGE SIGN (INFORMATION--4) 18" VARIABLE The j-nincorpomted \illage si!\l1 shall he placed approximately l,t:dj feet in advance of the approxima"l limit8. of an unincorporat('d ,-illage. l 78 IwaIT-OF-WAY SIGNS (I:\,FORMATION 51 ." (' ltil!:ht-o!-\\';IY .~igll shull \)(' :{O illdll',~ hy :.? I iII('J](',~ Ill~iz(' lIil.h 'I, I'kIk, tl('rilll!: ilil 11I1'11(' \l'I(I"grollillI. '1'1I'I" ,~"Igil ].~ 1101 rdl"l'I'1orlz('d. l1l,}1l'' ~1' ,,'1-("II.~ '~11'.l11 Ill' IJ]'\('('d alollg ,h(' riglil-of-lIu\,, lilli' ill an',I" ,,J]('r(' 1l1:l~' il\.~1,dl ,~igll" t1wl',t' , 1 1.','.11'1"' " 'I 11'lld"III'\' to huild up alollg ,1](' righl-of-II'a,' 01' til an'a" I' I' .' II"I~' ]I ,II'' I'Id. >1I1,~h. IH'lllg dUll11)('d Oil . '. rlght-o!-II'a,\,: . III II'}]('I'I' IIII' p1l1ili,' 111'('lb 111 hi' illfol'll1('d of (lip pJ'()I('I'tioll 11I]('n' o11wl' of il.~ I'Ll, ' t'.I1"\\'. (1111('1' jllri"dil,tioll" "ill1ilal' a" dl'I'llll'd rlt! 1t -II <. 1;1'1"('.":,";:1 r.\". STATE HIGHWAY RIGHT OF WAY EtjGROACHMENTS RESTRICTED PERMITS REQUIRED "OR l~' ,.;hall 1'011";]";1 01' ''iI'' or more i \[ :2 alld or \[ :)( markl'r,.; :ll'l'angl'd :1"; ~hu\\'11 IltHI 101 'ill',j Ilot Irs; lhall :200 1'''('1 h,,~'on,j lit" ilil('r";('I'tioll 10 1'('11";,.;11]'(' Ih" Illl>l1>,i,.;t,.; of the ]'(lllt(' Il('ing I rll\'l'1('d, ~('(' fig", 11 :lIld I,)' T\lI' l\[ :2 ulid. or \[ :) i HOlltl' \[,ll'k('1" ,.;1t:l!1 I,(! 1l"I'd i(( litis a,":,rm hl~' tlt]'(lllgh 11rhan an'II"; alid ,11 t}l(' lir,.;t lU('lltiuli hr'\'Jlldlllll'I':'l'I,tioIJ> ill rl11'l11 an'IIS, [ll IIl'hln ,Jj'('II"; tlti" :I,~,~l'll1hly ,~h,dl )11' 1l1011IlI('d nol Iltall i ic-et aho\"(' tIl(' pa\'('I1l('nt lind liot II''';''; thilli I fool fl'Olll IIi\' (dgc of the ('I\rh. In nIl'll! ,In'a,.; thc a";";l'll1l,l,\' ,.;hall hi' 1l10\IIII"d Ii' '.." I' thl' grl'at- ",.;1 yi,.;ihilit~, IJlII in nIl 1'11."1' II''''' thalli 1'1'1'1 fl'Olll Ill<' "i1lom of the a"";('lI1hl~' II' tIl(' pa\I'Illl'll1. IWIUL REASSliRANCE :\IARKERS Th(' !tlll':,1 !t1':I~~lIr:IIlI'(' .\lul'k('1' "\,";'~I'Ill)'h' l'IJIl~i~IJIlg "f ;'11(' "I' I1WI'C 'II I :llld III' 'II ,-)1 [10111(' .\1:ll'k,'I'~ ~h:11l 1)(' J(lI':lll'd :11 11111 I,,~~ Ih:11l :2mill' illl('I'\:lk :-'1'1' Iiglll'l , 17 :illlllg I Ill' Ilig]m:I,\', Thi~ :1.-;,I'lltld\' _"kill ),(' 11l1l1l1ltl'd Illlt II'.",,, 111:111 1 1'1"'1 fl'nll>ly, Jill II 'I ill I I 1'1) II I' I I' Ia I 'I '( I tlll I l\:lf.\ ,\'1' III ' II , I' Il 1\\ I 11'1' I"\ "\ II ( ,\1'\,1'1, - l\" \1 I Ill' \1 ,'I')IIl\\ill;,( lh(' l>r'." I. 1 ", III IIii' 'IIIH'l'''('('\- nl ll tl' 1111111 )11 llll! f i l II I' 1' , - , '';1 'I' I"I", - II"I 'I'j1"\' ,'I "' "' I '1111'\ ,\'" II: (II 1)(' 1'1:II'('d ,\'Il1'III'h' l\ppf'"\ \1I11t'l' I l t'' til"l' ,-,1)1) 11'1'1 III ' Illll"',I','111l11. adII ..IUl II \1 i )1'1\\'l1h' <. !>I' nl"'II'd "Il 'I till' 11l\\TrJ11 1l,1 1'111'1 \\'ill 1)(' t ):11 nllt I(:,-"-:-- 111''111 I 1'1"'1 a!>II\'!' 11)(' ,.Uft',,II 'I' "I' till' I'llI I " 1111 '\ :llld ,,!ta II 1M' lI"t !t',"" l!tall Ii 11'1'1 11111' III I I!'I , Ihllll III 1'1,('1 fl'lllll 11)(' I'd;,(' Ill' thl' fllllt!, Fil!lIn' I~I"III)\\' 1\l'il 'al appli- "a!illll" Ill' :-'1"'1)11,1111'\' .flllll'lillll .\""l'mhlil''', JUNCTION SECO:,\DARY HOt TE D1RE(,TIO~ ASSE:\II~LY Thl' :-'I'('ont!al',\ 1:1l1111' Din,(,tion :\,,- >'{'mhly (',m"i"l ill;,( "I' I (Illlt(' .\In I'k('1 1\11 IIIld .\[ .-) \\itll DiJ'('('tiollal .\1'- filII' (.\1- 1;.\1" ,,!t:I1! II(' p1;l('('d approxi- :mo IIlllt('ly 1'1'('1 ill Ilflnllw\, of tlw intl'f"l'('tioll III ,,,!JIl\\ the diJ'\,('tioll uf thl' illt ('f"l'('t iIl;,( IIlIIII',';. IIl'i~dlt IIIlt! 1:111'1'111 di"talll'I':-i ,;hall hi' tltI' "11111(' a,; 1'.)\' .flllll'tioll .\,;,;('m- hli('". OVERSIZE STATE AND U. S. DIRECTIONAL ROUTE MARKERS --- o0: S'" V> .'~.".. V> FIGURE 18 88 ~E(,O:\"DAI{Y .J CX('TION PA"'EL Th(' :'1'I'fJlldaly ,lillii'I i"ll I'nllvl ,,11:t!1 !Jv ;1 Ii"ri.ontal n'l'tallgle :21" \ ~I" ill "i ,f,(' , It "lin!1 Ila\(' bbl'k 1('llvr" Oil \\ liil'- 1':I('k,grtllllll! :llld ,,11:111 II(' r"'II' -Iori zet!, TIll' .J\llj('tilill 1';111"I-;JI;dl II(' \I"l,d "Ill\' \\'illi ItOIlII' \Iarkl'r" (\1 I :llld or \1 ,)) ;1" ,,1i"\\1l ill til( I~ I, IJUNCTION I M-IA 24" x 9" TYPICAL INSTALLATION OF GUIDE SIGNS FOR. SECONDARY ROUTE INTERSECTIONS :,.~ ( ~ T . '" ~"',~ c ~ ;;; 0 o. ":==J'--------S.'R:. =13'- t t I---- ,," I 500' ~ I b ~ r :; C - - - 300' _I ZOO'--1 ---, '-----~SR-;;-'3-,;-65.R;:;;-.-:7->,. 90 ... nJ~ ~ FIGURE 19 E SCHOOL SIGN STANDARDS . \ k\l'! r( nl!'nl of Puhli(' ~afpjy !ta" i"sued sp('C'd zonlllg ",'""e (,;c.or'~1l"a ill!' s'pt'pd oj.\"(,'llI(,le.; tran'\l.II.g on !t.lg!tlyay" and "treels ~ .-Lo'l'!lh1l1l11Ol1O""()-foo( I':ldius oj'(. 'n~r, y "I'I100I 'In (III' ':-;t a t (' oj'(,, ('or'gl:!, S.,tjtlJbIldOll.r:dl ".'1m1"1d,\\.pC,! ]H,('n :lp a('('Iu::nt pro\('d seltill!!: '.' 01 :-;('hoo] "lgn f " orth Oil sjwl'ifi('al iOll" 11,1gll\\'a~'" and for tIll' ,,1 n'pl" dl" ap- ,;,n. U:'C', I \ril hin 1IIl',se ,,('!too] ZIHH\S. dUll!! ,11l( pfOll, I'lrds ;11'(' ~1, \'C'1l .' III ddall . III . t!te .. . tollo\\'lllg pa!!:e": Thl'''c "t.lll( , .... . 1 \ Z ...:('hOCl ... ('hildrell no"" t!te !tigl1\ray or "t 1'('('( . 3, School "i~n,.; i:-; ::\1 an' to 1)(' pl:ll'ed ill a(l\'alwc' of the "l,!tool ~'aroliuonndos f Illwn it a s(hoo] i" dl' on a "!itriaghh\kla~o'r Ill'('I'""ar~' to llc-"igllall' II'i( hin :1 s('hoo] ZOlle. 11](' 10- 4. Spel'd Lilllit.;igl\.'; (:-' 7) II'i1l1 AlI:\iliary S('hool Palle!" (8 -Ie) :)r IS ,il an' tl) 1)(' ('rel'led at Ih(, hl'gillnillg of lhl' ,,l'!100] zonl' to inforlll drlll'r.; of (he "]H'l'd limit I\'il!tin til(' ,,('!too] zone . .i. \'0 Parking :-,('hoo] I [ollr" "igll" (Slii arl' to hi' lI"ed II'111'n' parking Oil 1hl' hi!!:hlray or "treel adjal'elll 10 111(' ,,('hoo] PJ'()- duc('s a h:IZ:1 rdolls ('olldilioll, fi. Spcl'd Li III i1 ,.;j gn" (8 71 are to h(' 1:l'c('lcd at t !tc' ('nd of 1he ZOIH' t'a('ing I raffi(' km'illg 1111' zone (0 "hOlI' lhe mO(()J'i,,( (hat he !tas rl':ll'lll'd 1II(' l'nd of ,,('!too] ZOIl(' :llId to ."1'1 for(!t Ih(' '''!J('ed li III lI h('Yond 1he ZOIlI'. I. l'or(ahk :-,('hool "ign" Il'ith AlI:\ili:II'~' ~lop PallP] (8 S) arC' optiona] and n1a~' lip u"ed at a, "chool lTo""ing 1\'hNP ('ollliition,.. makC' it lJ('(I'.;"ar~' to stop t raffle at a definite poin1 in the highway or "I n't'l. ~. Portahll' ,";('\ll){.1 "dgn" \I-il h Auxiliary Speed I'anl'l (S-D) are optional :lIld may be u;,:ed at a point in the higlll\'[IY OJ' "tn'l'1 1I'!tC'I'(' it i~ 1l(,('p"S:Jr~' to ,,101\" namc to a 1011'('1' limit than Il:l~ heen pSbldishpd for tlw entin' /lOW', !II 5-1 36" x 36" 5-2 36" x 36" SCHOOL ZONE SIG The School Zone ign i. to give advance notice to dtiv that they are appr achin chool zone. The chool Zan e ign hall placed 100 feet to 500 f('N advance of a school zan . This sign shall be 36" x and where condition warr an oversized sign 4 " x..j " be used. The lettering shall be bla'k yellow background and i. not be reflectorized. See fi<01llSS I ... ~ 1 aBOVE _E"llO' UR8AN AREAS '~11 "Ot LUS I"'" ,11 ,_UKI O' 'tOo.o-., nW w .,...~: -= .-;;::::::::::::::: ,:~'! ~ ~ ~--+-wl .",_. . . j iT~: _$ .. .1"11 O]]dS OJ .,'$~ j ~~j. ~. . ~ll b j ~. j FIGURE 20 STANDARD LOCATl~ AfIID ERECTION OF SCHOOl SIGNS 95 .~. r POSITION OF SIGNS IN RURAL AREAS WIoiERE Pl,RKING 00($ NOl OCCUR All. SIGlfS ARE TO at ,11;'0 WIT" !OnOi4 or S(ilj1lOf LESS TOlAN 4-0 AllOVE PA,VEIoI[MT 9UIlFIQ ""0 "'~ 6~'O' FIlO,,", PAV[IoIEHT EDGE IF PMIKING OCCURS, SIGNS "'Fl.[ TOeE [!l(CTtI A1 7FOOT tlEIC~T ABOVE PAVEMENT: ",~,,~~ - .' " ." .bT ~5:5: 24 " T POSITION OF SIGNS IN ~BAN AREAS AlL SIGtiS ... It TO IE [llttTED "'nil 10TToo. Of SIGN NOT LESS T10IUI T' AeOVE P"'V[IIIIEM IN URBAN AREAS .1\"'0 NOT LESS TltA/'1 In fllCIot EDGE Of" 1l0AO'WAT ";e! .?';e; ~ ,...~ e ,,- .. -" ~ _ . 20 2 .- "."'" ", . y' FK;URE 21 96 Part II MARI\:INf;S A-INTRODUCTION Functions and Limitations of Markings 'ilirkin/!:~ h;l IC definite tunct ion~ to pprtol'11l in a proper ~chenH' oi 'ffie cont 1'01. I 11 ~OIllC ('lISe" tlIPy a reo uSl'd to su pplemcnj the regu b- lIir,oons 01her (1(I'I, I1.I;",ItI''mI' clciI~l"" ". j~ heojy" , oojbIl, teaI'm(I('r\''eI(~'PuhSs. ."11s('oII]ea' hs' tomn. ft"tH,h' e"I.Ir'gn01s1'1o1r Sl'gTI .I;I "',. I n n1Cl'lt,s, that not 1)(' rthane'- !o'er\"(' obt:till(,d a.; It ler.Y bdyl..etdheI.H1'I "e oj a mcan~ n0y1" coothne\'re.dnneng. ccpe. rt aIm.n s\[('h C{L.;('" reguIat'lOlls and \\':lrnin/!:" tllat I'ouhl not othel'\lise be made' clearly UIHkrst andn bl('. ~llIrkin/!:" :tbo ha\'(' deflllitp limitat iOJls, especially 11'11('11 ~lpplicd t () pa,-empnt and curl)i', \I'hel'(~ thry Illay lw entirely oblitenticd by :':IlO\\. are not clcarly \'i~iblc \I-hen wet. and arc not ycry dumble whrn paint- ed on surfacc~ (;:\l)()~rd to traffic \\"f'al'. I n spite of t heS(' limitation.s, howe\-pI', the~' hllYP the adnmtage under faYo!'able l'OIlditiollS thai they Clin conn'~' Ilaming or information to the \'phi(]P Ih'i\"('r withont diverting hi~ att l'1I1 ion from the road\I'n.\,. Legal Authority ~llIrkings shall be placpd onl.\' h~' thp ;luthorit y of a publi(' body or offieilll h:l\-ill/!: .imi~didion for thl' pUl'!)OSP of regulating, 11:tl'lling. or ~lIiding traffic. Pan'ownt nnd ('mh lllarking~. bf'illg ('X('lllsinoly Iyithill th(' hOllndari('8 of puhli(' hi\dl\\a~'~. should IIP\'('I' 1)p ill~tallpd ('XCPpt hy plddi(' authorit.\,. Iklin('lllor" ,111(1 markillgs on ohjP('h H~ a \Imnillg: of thpir hazardous lo('al ion .; an' also norm,l!ly IYithin the high\\ay rig:ht-ofwsy, and should 1)(' ~ld)j('d to lll(' "ame ,imisdidional J'('glliatioll.;, S&aadardization ~llIrkillg~, II,h('n' lI~ed, .;11;\11 he lIlIiform ill c!e"igll. po.;ilioll. allc! appli('ation, .\.; ill til(' ca.;e of all othel' traffic ('Ollt wi dl'\'i(,(',.;. it i.; aimndJXU>lrladtpi\r'(~,t that ood ilml..:;ltrlkililtlll.0~,'; 1)(' 1IIIifol'ln ~o that they ma\' he n'('ogllizpc! Types of Markings ~larkings as ddilll'd 1'01' tIll' purpo~('s of thi~ 1ll11llllal :11'(' or :1 lI11In!J('r Ilf tyJX>s: 97 I. Panmwnl marking,.;: (a) ('enler lim',.;. (h) Lane lilll''';. I,u-l :\ o-pa;.;,.;ing-zol\(' mark ing;.;. (d J Pan'llwnl edge,.;. (e) Pan'llH'nt-\\'idth tran,.;ition,.;. (fl .\pprwwh to oh.-.;tnwt ion,.;. (g I :-'In'pl ('a r ('\ea rall(T line;.;. (h) Tmn marking,.;. Ii 1 :-'t op linp;.;. (j 1 ('ro,.;;.;-mdk lille,.;. (k\ BOIIII' din'dion,~. (II .\pprwU'h to railroad no,.;,.;ing. (ml Parking ,.;ptU'e limit;.;. (n) Word marking,.;. .J ('IIr1, marking;.; for parking n';.;tridion,.;. :). (lhjel't marking,.;: (a I (lhjpd,.; \\ithin tlll' rua(hm~'. (hi Ohjed,.; adja(,Pllt to llw road\la~. +. l(<'Il('I,t or markpr,.;: (al IIazard marker,.;. f.hl ]lplineator,.;. Materials TI\(' Illo;.;t ('I)JllIllOII Ilwt hod of applying 1)<[\Pllwnl. "\11"1" and object Illarkillg,.; i.- I,~' lllPalh of paint. ,\ 1""ltinuou,.; imprll\"llll'nt ill paint. and ill 1''1UipnH'llt alld Ilwtllild;.; of appli('alioll ha,.; n'~liltl'd ill a \"ery lI'idl' U,.(, of pa\Tnll'111 markillg,.. Equipll1Pllt i,.; ill 11"(' 1kll i,. capable of plI' or ,.;pe('ial marking,., at interH'I,tioll"; or 1'\";"\1 !II'I'I', at a rea ,.;olla hll' 1'0,.;1 . .\ rplali\'I'I,\' n'('l'nt dl,\'plopmPllt in pal'l'llll'llt m:lrkill!.!:"; i,.; tllP use of minlltl' gla,.;,.; "heal!,.;" (al'tuall\' tn\(' ,.phen''';j I'mhl'dd('d in the pare- ml'nl marking material 10 prudll(,1' a rl'1 rodin'('t in' rdl('('] ing ,.nrfaee, '1'1](' gla,.;,.;-I'I'alkd ";lIrfa('I' n'tul'1l"; a gn'at!y inl'l'l'aH'd pllIlll,rtioll of the illl'ident lighl !Ja('k in the direction of it,.; ,.Olln'I', alii I (','In'';I'''; thl' mark illg,.; II' appl'ar hlillinou,.; al night IIIHlI'r Illll"mal hl'adlighl illg, While the hl'ad,.; marking,.; han' litl!I' or 110 I'fll'd in lhe hy night i,.; gn'all,\' impro\'l'd, da,\\'tlilllhHo'u~h11111'1](l'i,.1;1il1,!itliiati\' of the co,.t of ~u('h rpfi('I,torizPd marking,.; j,.; con,.iderahly highl'r tl];(I, lor ordinary traffi(' painl, a nUIllI)('r of higl1\\'a,\' departml'lIt,; han' rl'l",rtl'd that the illl']'('a,.;pd lifl' of thl' markillg,;, l',;pPl'ially at hpa\'ily-lr:II('ll'd locations, mo]'('thHlI ('Ompell,;ate,; for tIll' diffl'rPIII'e ill l'O,;t, 'k'II"~ ma\" abo 1)(' ill Illl' form of "mall 1lllit, of 1ll('lal I 111'11 I",' . Pa"rn1l'11 ':'1 '11:lI'llt'd to or ,,('I ililo 11](' pa\TIllI'111 ""l'bl'I' :-'lll'h nl'\I<'II,1 ,I . _ othtr .', ' rt'I't:11112:1I1:11'. l'olllld. 1'1' of "]H'I'I:Ji "Iwpl', alld Illay })(' a"- anJ, lll 11 ...... l n1\'':l1\111 ('(. H 0 ~'ol id or 1'1' ),I'OkCII ill lIlt' I'111(''', pa\'PIl]('111 "llrla, l'l' "wI II )(' n1' j H'1'I1l:l1 11'1 II .".'.a..l 111111" '1 f' I fi1 ll' p'I\'1 Cm l '1I11 l11a l, 'k II 112;';. alld "hall \)(' "1'1 .'0 lIwI . tlll'll' , ('llklr.' '\' "1)('1'1 1 1 " 'lIr.t:ll'I'~" rt ,I . '("1~I''lIliall\" ' . . flll"h . \\'llh till' pa\TI11I'1I1 . ""l'lal'l' , upPf'r, l'I'l.d ill l'ilIIIIIIIlOII" 1I,llla(t, or ,,('pal'alcd 1>y "Illall .I.Ill'\" ~'pal'c. " _~. I~' ~I',I'h' I'li ll:tl lil pp1't1.XIII1.1,1 . ,.d 111]1'1'" lIlt' 1t-II1.!:Ih a "011.1 I I"1111' of a "illgl(' IlIlil. 1:ith('1' \'\'J)(' of I" P\'('''I'I'.I\)(,' I 'III I Il'l~ 111:IIIIWI. I 'al'- Ii.nr n1,'\.\' II' II~I 'hollid I", 1:lkcll 10 "c,' thaI :llilll'I11('111 :lIld 'pal'illl.!: an' tirtJ1M I':t rl' ~ , til ill"III'l' :1 gillHI appparalll'l' . .....un1lt . . . 1'1' ~h'lll \11'\:1 I 1I1~(' ~. , h:I\T :1 ""1'1:.11'1' I Ilat .' \\'1'11 \'('IlWI.II 1ll'll..!:III . 11111 11'1' II ]I' '. of tr:tflil'. Ihll' 'illltl'a"tllll.!: \\'1lh till' I'olill' 01 lI\\' pa\IIl]('III. ac. llol1 'II' , ill"PI'I" ,hail IH' 0'1 ))('I'lllall('111 1'0 \or:, a" "p""1.f'11'1 1 l.or pa\'I'- \olln]('1 , .\ 'kIIill"~ 111,"1'1" "hall \H' IHl1 I""" IlwlI I illl'llI'" ill di:lIl]('t,1' if 1I11'llt I'tIlJllI 111:11 ",' ' I, 0 \. "I'''1)lll . l'o\,llIl al"h' . . 1''1 III \'al''111 .' an':, IlIo! mOI'(' I!J:III \" 111l'1ll''' apart. . '. . II ,I! 011]1'1' "haIH. "1'111('1' 10 "1'1111'1'. :llId "hall Oil Irall.~- l hc' ~p:t"'II'I1II'~ 11ll!' mill'" . IIJ:lIl :\(; 1I11'1\\'" apal'l .. . Oil IOlll.!:lt lIdlll:Ji lillI'" \c'rot' .. .I. I I I ' \ ' . !'hall halT 1'1l1l11,lt-d ,111'1':)"1'''. pn'''Plllilll.!: a "llllH,th "01110111' 10 II\\' \\hlI,I, u( whi .. k", alld "h:lii 111>1 pl'lljl','1 1ll1)j'(' Ih:lll 1l111'-1J:l11 illl'h ahll\'(' tIll' W\'l'! "i till' P:l\'I'Ill"III. Thl'~' ,,11<111 ])(' !)(,I'IlW 111'11 I 1\' li:\l'd ill p!;Il'I' 1,\, snch"l' },,,Il~ Ill' .~illlil:11' 1'1'1'1'1'1 i\'I' dl'\il'I'';. :'imilarl~. IIIlit \,'111'1'''. "."1111>111,. Ill' "ll'ipl'" 111<1,\' ]1(' :ltl:II'hl'd III Ill' !'C'l illt" thl' p:I\TIIII'111 "lll'fal'I', a" :III alll'I'llal i\ I' l\'])(' ,>I p:I\'I'I1]('111 markillg. Thl'''I' ~holJid \)(' 1'''''I'1I1ialh' f111."h \\il1J Illl' pa \Tll](, I II .~l1l'fal'I. sntl "h,,"ld II II! \"""'1111' l11l1ItJiy,lippl'l'y \\1JI'1I \\1'1. ('''pl'l'i:t1ly if II)('.\' sn' "i "IlIl"idl'I':l1>II' :11'1':1. TItI'Y ,~hOllld \1(' \,1' pl'I'IlI:IIIl'111 I',,jlll" :l~ ';pl'l'l- tit'\\ i,,1' pa\TlIll'lll 11I:II'kill.i2:" :\ll'1al alld pl:I,1 ii' ill"I'1'1" :11Id II:tI 1ll:ll'kl'l' 1111il" ill Ill' 1111 tlll' pa\'I'- Illl'llt "lII'fal'l' al'l' 11~Id pl'illl'il':tll~' ill lId,:111 :11'l':I". \\1JI'I'l' 1ll':I\'\' II':dli, rapidly dl'''II'll~'~ p:lilllld Ill:ll'killl.!:". alld \\'Ill'I'l' 11'1"i1II'lil l'I'pailllilll.!: 111,1 lIlIly i" 1'11"11." },111 (':111"1'" lll1dlll' Irafli,' dl'la."". III I'IIl'al :11'l'a" "))('I'd II! lIpplif'atillll l1\akl'" P:lilitilll.!: 11](' pl'l'fI'ITI'd 1'1l1'1ll III Ill:ll'kllig :'III'I'f',,~illl l':\pl'l'illll'III" ha\'(' 111'1'11 l'I'plll'll'd \\ilh J)(,I'IlWIII'111 hllill-ill \llIYl'mf'1l1 J11al'kill12:~ 0\ \\hill' Ill' 11l!III'ld "Il]II'I'I'tl' Ill' ilJi:lid !llil!;.' Ill' l,jlH'b. TIll' 1I,~1' IlI1 IIII' p:I\"IllI'111 ""1'1':11'(' of ,;llIall 1l](,lal Ill' pLI'1 it "I lid, \\ith ill'I'l'll'd l'l'fl""11l1' hillto]\.; i,; 1I0! l'l'I'IIl11Il1('IIIII'd. 1-::\ pi 'I'i I 'I II'" 1Ja'" -hOIlIl Ihat llll'y ":11111111 hI' kl'pt ,ll'all alld 1'1'1'1'1'1 i\I'. :11 III )Ill'~ :11'l' :1 h:wml III 1111111l1'l\,1,.... Lal'gl' "J11l1"III";lllil" },"111111". Ill' hal'''. 0\' 1':t,,1 il'lll1 01' "oll"I'I'I"~I'\'I'l'al ' I I I :111'111". hio: -h. \\'11 1 I (l! ' \\J'1 I lOl11 1'('. {'('ttl\':-;, I'19I lt~. ~\'nl1)i)~, Ill' n1(\-..;~ag(\;-.;. i~I:tlld., an' ia\Il!'ld ill "" III I, ,ilil'" 10 l11ark )H'dl'''ll'i:t11 or 111 :t'"i-:t ill f'h:lllllpliz.ill''"" I]':1 JI'II'. 1II I. )](.,H' :tpp111'':1"1 111I\.; t 1ll'." :11'1'. I.II ('I '1' (,,'1. ('III'1l~ or islands. They are not a suitable alternative to signs or pavement markings. They should not be located where they constitute an unexpeeted hazard for motor vehides, and their use on rural highways is strongly disappJiflved. Object markings are ordinarily painted direetly on the surface of the obstruction. If the surface will not retain paint readily, some flat surface of wood or metal should be painted with the proper marking and attached to the obstruetion. Where a refleetorized coating is desirable, it will often be necessary to use a separate surface for satisfactory application. Reflecting buttons or clusters may be attached directly to the obstruction or installed on separate posts immediately in front of it. Delineators and hazard markers may consist of single reflectors,dusters or reflectors, or small panels of uniform shape covered with a reflecting coating, mounted on separate posts. To be effective they must be of retrodirective character and of adequate brilliance. Colors Pavement markings shall be either white or yellow in color. The correct color for yellow traffic paint is the same as that specified for. highway signs. Bright metal buttons are to be regarded as the equivalent of white paint in pavement markings. White shall be used for: 1. Center lines on two-lane rural roads and city streets. 2. Lane lines. 3. Pavement edges. 4. Streetcar clearance lines. 5. Turn markers. G. Stop lines. 7. Cross-walk lines. 8. Parking space limits. 9. Route directions. 10. Word markings. For the following markings it is recommended that yellow be used, but white is permissible: 1. Double center lines on multi-laned pavements. 2. No-passing barrier lines at: (a) No-passing zones on two- and three-lane roads. (b) Pavement-width transitions. (c) Approaches to obstructions in the center of the roadway. (d) Approaches to railroad crossings. The markings for which yellow is recommended are all solid guide lines or regulatory lines to the left of which it is unsafe or illegal to travel when they are applied as prescribed in this manual. Yellow is favored for several reasons: 1. It contrasts with the normal white center or lane lines and thus gives emphasis to the hazard. 100 2, Ycllow lw" hl'pn ac('ppt ('d ;\" a ,.;ym holic Il'a rn IIlg ('0101' in ";Ign,~ :Ind sigllu],.;. It i,.; ('Oll.,.;i";1<'llt Il'jlh thl' ,,.;Iundurd for no-rJ:l,.;sing-zone Illurk- 3, , (f' hithert" appro,'('d h~' the ,\n1('riC,11l .\,.;,.;ociatipll of ~Iaje 1II,,:- High,ru," Oflici:i1,.; ulld " In 11,.;e III nl:ln~' ,.;Iat(',.;, r('urII Ill,'1I.Kl'ill""'''; t" ,.;holl' purking pJ'()hihilion,,.; ('ol'{'r"d h~' ";Ign,.; or '(H'(' ,.;h:i11 iJp \TllO\\. Of{'l1:Ill,r1'lkI'Ig:"- "n 1'('l't ical ";11I'fa('(',.; of . ohj"cCl,.; Il'it hin (h(' rO:ldIIU\, 01' dan.gc]'11' (J repainting hJ'()kpll lill('''; a('('lll'alel.l ,Illd npa11y, pl'l'I11ilting a "a\'ing (J more thull (iO P('\'('('lll in paint. Iri1h Idtl(' ()j' no in('l'ra";I' in tl1l' cost. (J applicati"n. :\ broken line, IIi1h .~egm('nt,.; alld gap,.; \Iell proportioned, ,Ipppars to he a,.; eHedin' a,.; a ,.;olid line for gnide purpos('s. Oil I'llra] llighll'uys ('ommonl~' \1H'd ,.;1 :Indard i,.; \;"j-foot ,.;egnwllI s Il'dh :'?;"j-foot gap,.;. In the applicatioll of :1 gi\'Pll gallonage of paillt P('I' mill', ";\lI'h \'('lali\'('I~' mort ,.;rgnH'nt" Irill gil'(, :1 het tel' Jilll' th:1l\ if ]ullger ,.;egmpnl,.;, with l.'OJTei;pondingl~' longer ga ps, are lIsed, On t lip ot her hand, \'ery ,.;bort eegment,.; and gap,.; ha\'p heen found to cau,.;e an lInpleasant fiickerin~ eensation, On urban strret,.; tl!(' liI!(' segment,.; :md gap,.;, especially the latter, mould he con"i(kra hly ]'('dllcec! in length. Short spet ions of broken line, such a,.; a)'(' lI,.;ed for interspction appl'Oac1ws, requirp the Ibe of Ibort segments, c!o,.;e]y ,.;paeed. Broken lines are al,.;o prpsnilled for street ear clearanc(' lines, and for tum markings. A solid line sball alll'ays he used for longitudinal markings where ::: line is ~f a reglll:ttory ehara~ter and is not ,to lw crossed, that is. center hnes of II\'O-I\'l\" mllltl-Ianpd roads WIth an evpn number of lanes. and for lines indicat'ing IIO-passing zone,.;. . . In.a comhination striping of solid and hroh'n lilH'S, the ,.;olid 01' barher hne has significan('(' only if it is on the right-hand sidp of the com- 101 bination stripe, as viewed by the driver, i. e., in or adjacent. to the trafli lane to which it applies. 1 Width of Lines Longitudinal pavement lines shall be from 4 to 6 inche" wide. The most common width is 4 inches, but 6-inch lines, favored b a number of highway departments, provide added visibility. ~a: rower 3-inch lines have been used as a means of economizing in pain; but they are not regarded as adequate for standard use. \' Transverse lines on pavements must be much wider than longi. tudinal lines to be equally visible. Stop lines may have to be as wid as 24 inches where approach speeds are high. e Reflectorization Reflectorization for better night visibility is desirable for almost all markings, but it is neither a practicable nor necessary requirement in all cases. Reflectorization is of doubtful value on well-lighted city streets, for example, and it is not ordinarily essential for center or lane lines where there are no special hazards. At lea"t the following mark. ings should normally be reflectorized: 1. Center lines on multi-Ianed pavements. 2. No-passing barrier lines at: (a) No-passing zones on two- and three-lane roark (b) Pavement-width transitions. (c) Approaches to obstructions in the roadway. (d) Approaches to railroad crossings. 3. Striping on vertical surfaces of objects in and adjacent to the roadway. Maintenance All necessary markings shall be kept in good order and dearly visible at all times. Unless this is done they may create seriou8 hazards by giving a fal8e sense of security, espeeially in the case of cross walks. The frequeney of repainting depends on the type of surfaee, composition and rate of application of paint, climate, and volume of traffic. Particular care should be taken, espeeially in the case of broken lines, to paint over the old markings as exactly as possible, otherwiHl they will appear increasingly ragged after suceessi"e repaintings. 102 B_PAVEMENT AND CURB MARKINGS ter (',ell Lines t' line is used to designate the center of the tI:a\"E~led portion sCJtJIa)Ia.l~creoesun'1e"'I1I\'1S\'If',l'l,I.t"te. rC,'I''ol]lflTa,t"Vhinee.gmpet.arnvat-fe\fm\i'Cl'ed1n'tlItl1, b. o't}1 eI'lrecj transi"tIOn, On all m J,Ons., 1, !H" 1 er 'sOllle C''ll'C'UIll- I,t nee(I not } )t' at the g-eo- ajor l'lIral high\n1vs having (rica (e ,. . . '. . alInIertes n\t ' eIIIInIllb'"r of rural roads, lanes, a,nd .o.n man.v, urban streets and ]Pss nllcenter Imes arc necessary and should he applied po hout the C'ntire length of the pavement. In urhan locations thrdoiol/n-!: some r11ral roaeIs \Vh. ere a contJ' nuous cent.er I"me 1S not reqUl,re(I , :ort sections of center line are u~efuI, on ap?roaches to busy inter- _tions, marked cross walks, or railroad erossmgs, and around elllTes o,'er hillcrest s, \Vhen so used, 1he center line seITes both to mll'll :; any unusual condition and to organize and eontrol traffie through a hazardous or congested zone, A line marking the eenter of a one-way roadway is a lane line, Center Lines on Rural Roads The eenter linc on a two-lane paved rural hig!l\\'HY shall be a broken line, not less than -I nor more than () inches wide: white paint on hlack pan'ment or hlack paillt ou \"hite pavement, Line segnwnts Lj feet in lenp:th. \\'ith ~;j-foot gaps. are re('ommelH!ed, Center Lines on Urban Streets Ccnter lil)('s on city stTeets shall 1)(' broken lincs. not Ir"" thallt illl'IJ('s nor mol'(' than () inches "'ide: \"hite paint on blae].;: pan'nwllt or hlac'k paint oll\\'hite p,wenW1I1, To presen'e the dIed of eontiHuity \dwre t rattic' i,; }wa\'y. speed,.: are 1()\\', 0]' hloek" short, 1he line srgnwnt,;, ,Ind e"pec'iall~' the gap,;, sho11ld he relatin'I~' "hor1. Long "cc'l ion,; of ';\I('h line,.: "'!Onld not he u"cd on Cit n'p!s j)nl\'iding IPss than II\'() lilJ(''; for f]'ee-mo\'ing 1raflie in eaeh din,(,tion, ('xC'iu"ivc of parking lane", Thi" minimum "tn'et width doe" not apply to the lISC' of sho]'t sedion" of c'ent(']' line" a]'()\llld (,l1ITC", on']' hjll(,\,c'.~1s. or on app]'ml('he" to imporU!nl intcr"e('tion,.: and marked ('m"" \\'aII, ", Shorl sec't ion" of ('en leI' line for r('gula ton' pn rpOH'" "ha 11 1)(' of sol icl drsign, :-'mal1 unit" of llH'tal or other mate]'ial atta('lwd to or ,,!'t into thc pa\'C'llwnt ,.:urfac'( an' frequently uscd in eitie" a" an altel'llati\'(' to painted markings, On \\'iek. high-,;peed honl('\'I\l'cb. and on ('cJlItl'olled-ac'c'pss higll\n1~''': in mban an'as, ('c'nler-lint' st andards shall lw the ,;anw a" thosr for rmal highways, .\ppli('ations of ('pntel' line" arp ShO\\'ll in \'IlriollS illustrations herein, partieularly figure,.; ~~, 24 and ~7, 1m Lane Lines Lane lines are helpful in the organization of traffic in it~ prope channels, and in increasing the efficiency of the use of the roadwa; surface at Qflngested locations. They should be used: I. On all rural highways with an odd number of traffic lanes. 2. In addition to the regular center line, on all rural highways of four, six, or eight lanes. :3. At important intersedions, at cross walks, and in dangerous locations, on both rural high\vays and eity streets. \ L At congested locations, particularly on city streets, wh(,l'e the roadway will accommodate more lanes of traffic than would be the ease without the use of lane lines. These include: (a) Locations between loading islands and sidewalk curbs. (b) Other locations where the normal laJlC width is decreased. (c) Approaches to widened intersections. ,J. On important one-way streets or highways where maximum efficiency in utili,mtion of the roadway is desired. Applications of lane lines are illustrated in figures 24, 2;) and '27. Lane Lines on Rural Roads Lane lines on rural roads shall be broken lines, not less than 4 inches nor more than (j inches wide; white paint on black pavement or black paint on white pavement. Line segments l;j feet long, with 2;j-foot gaps, are recommended. The transverse spacing of lane lines, that is, the lane width, should not normally be less than 10 feet. Lane Lines on Urban Streets Lane lines O!l city streets shaJJ be broken lines, !lot less than 4 inches nor more than G inches wide; white paint on black pavement or black paint on white ptwement. Due to relatively lower speeds, tllP line segments, and espeeially the gaps, should normally be shorter than in rural areas. In limited sections of lane lines, as at intersection approaches or between loading islands and sidewalk curbs, the line selSments and gaps may be as short as 4 feet and of equal length. The lane ,,,idth defined by lane lines eihmild not normaJJy b(' less than 10 feet, but a minimum of 9 feet is permissible where a maximum number of lanes must be made available, aei at a signalized intel'eiection where provision must be made for the mOeit efficient storage of stopped vehicles in a street \\'idth reduced by the presence of a loading island. On wide, high-speed boulevards and on controlled-access high Ilays ill urban areas the standards for lane markings shall be the samp as 1hose for rural highways. 104 N~1.\Poa_psassi:n'g;inZg onZOels1(':'; :.;hould be e:.;tabli:.;hcd at yertieal or horizontal U;yes and e!se':'here on tm)- ~nd three-lane hig~,Yays ~d1ere .pa:.;sing Crnustthcbre prohibltcd be('au:.;e hazardous ('onc}"ItlOns. of dangerously re:.;tr]('ted Sight chstanees or ~ no-paH3ing zone shall Iw marked by a solid barrier line placed as h' right-hand element of a combination stripe along the center or t ~e line. This barrier line shall be yellmY. !ThIe cl omhlina.tl011 I'nle may eOll:';'ls.t 0 f "eltlWI' 0 f' tIwfo' ]mlY'lng. as 1'11 us- trated in figure :2:2: I. ,-\ normal broken "'hite center or lane line continuing through the no-passing zone, \yith the solid harrier line placed to the right of it. \Vherc no-passing zones in opposite din'c,tions O\'erlap ou a two-lane roachnly there ",ill he a solid barrier line on each side of the hroken c'enter line. \Vhere the nopa:.;:.;ing m.,tridion applies only in t he opposing direction, the harrier line ",ill appear to the left of the broken eentel' or lane linc amI ",ill not 11a\'e any eontrolling effect ex('ept OIl traffic in the opposing direction. 2. A douhle line replacing the single hroken center line un a tm)lane roadway, of which the right-hand stripe is the sulid harrier line. \Vlwre no-passing zonc:.; in opposite directions oyerlap, there 'Yill be a double :.;olid linc, and \yhere the no-passing re:.;tridion applies only in the opposing direction the solid line \yill be to the left of a broken line and will not ha \'(' an~' controlling effect. The harrier line shall be not less than -t nor more than (j inl'lw:.; ,Yide, and shall be separated from the adjacent stripe by a space of not less than :2 nor more than -1 inches. It should normally be refledorizcd for increased emphasis. No-Passing Zones on Two- and Three-Lane Roadways On a t'H)-laue roachnly the combination no-passing line shall follow the center line throughout the no-passing zone. On a three-lanc road the combination line shall start from the left-hand lane line of the ('elltel' laue and :.;hall ext('nd at an angle of not kss than 20 to 1 across the center lane to the right-hand lalle line at ilw beginnillg of tlw llOpassing zone, and thenee extend along the lane line to the end of the zone. ::\o-passillg-zonp ",igns (J~--1(i, H.-Ii) may he used to ",upplement the pavement marking", here prescl'ibed. It is a",sumed that on higll\H1Ys of four or a great('\' eyell lluml)('r of lanes it i", not I1c('es",ary to ('I'OS", til<' ('el1ter line to O\'ertake amI pas", other vehicles. '::\0 ",pecificatic)J]s, therefore, are p]'()"icled fol' the markillg of 110-pa",sing ZOl1es 011 such high,ntys. The double (,(,l1ier I();) is to be regarded as a continuous no-passing marking, consisting ~~wo barrier lines which must not be crossed from either side. warrants for No-Passing Zones The warrant for the establishment of a no-passing zone depends on the assumed design sp~ed of the road and t~e min.imum sight dista~ce essarv for safe passmg at that necrve is'the distance at which an eUrface can just be seen from ano speed. object 4S~lgfhetetdlasbtaonvcee on the ther point 4~ feet above a vertlCal pavement the pave- S~Uednet,tearsmiilnleudstriant ed in figure 23. similar fashion, Sight distance on a horizontal curve measuring around the embankment Jr Ao other curve sohbaslltrwucatriroanntthaant oc-uptasssom.ffgthzoenve,ieawndonshtahlel inside of the be so marked, curve. when the minimum sight distance for the assumed design speed is equal to or less than that listed below: AIinimum siUht Design speed (miles per hour): 30 _ distance (feet) 500 40 ---------------------------------- 50 _- - - - - - - - - - -- - - - - -- - - - - - -- - - - - -- -- - - - - - - - -- - 60 --------- ----- --------- 70 ----- --- ----------- 600 800 1,000 1,200 The beginning of a no-passing zone, point a in figure 23, is that point at which the sight distance first becomes less than that specified in the above table. The end of the marking, point b, is that point at which the sight distance again becomes greater than the minimum specified. In no case shall the marking be less than 1)00 feet in length. If the actual no-passing distance is less than 500 feet in length, the additional length of marking shall be added at the beginning of the zone. On urban streets it is not ordinarily necessary to mark no-passing zones. Speeds are generally low, and a normal center line is usually sufficient to keep vehicles in line. On boulevards or parkways, where no-passing zones may have to be marked, the standards should be the same as for rural highways. Pavement Edges Line markings on the pavement have sometimes been used along the sides of the roadway, especially Oll bridges, to indicate the limit of safe approach to the edge of the pawment. Experience has shown that such lines are easily mistaken for center or lane lines, with the result that drivers attempt to pass to the right of them and so r\lll off the road. They are therefore not reeommended. Reflector markers are much preferable for the purpose intended. 107 VERTICAL CURVE 0,0' Begin no-passing zone Sight distance becomes less thon minimum measured between points 4~ feet above pavement b, b' End no passing lOne Sight distance again eKceeds nWirrun No1e: No-passing lones in opposite directions mayor may not overlap, depending on Q1intmeM. HORIZONTAL CURVE I I I I (),o'()~ . ~ l,O~e~\.co,e~ : ~~\~ ,t> ~o ,\.of\ I ~o' ~/.t.V t ' " \\f\ : I I I I 0, 0' Begin no-passing lone Sight distance becomes less thon minimum measured between points on center line (or on right-hand lone line on three lone rood'> I I I I ~"'O-h I ftl) ass//" I Oij.~Cli 'g I'O'J~ I I c 0..,''.'Oi ~ 0' 'o/), I I : 01t!(/) " I I I I I I I I b, b' End no- passing lone Sight distance ogoin exceeds rrinimum No1e: No passing zones in opposite directions moy or may not overlap, depending on olinement. Figure 23.-Method of locating and determining the length of no-passing on vertical and horizontal curves. 108 jI FROM 4 LANES TO 2 LANES Figure 24.-Typical pavement-width transition markings. Ion Pavement more than 6 edge lines shall be solid white lines, not less than inches wide. When used, they shall supplement r4atnh~r than replace standard center and lane lines. r Pavement-Width Transitions Line markings should be used to indicate points where the pavement width changes to a lesser number of lanes. There are a number of situations possible, as illustrated in figure 24, depending on which lanes must be offset or cut out, and the amount of offset. One or more lane lines must be discontinued and the remaining center and lane lines must be connected in such a way as to merge traffic into the redUCed number of lanes. I-ines marking pavement-width transitions shall be not less than 4 nor more than 6 inches wide, and of standard center- or lane-line design. Converging lines shall have a length of not less than 20 times the offset distance. Through the transition area, in the direction of convergenee, the line separating the opposing directions of traffic should be of nopassing-zone design, either the double solid center line of a multi. laned road or a normal broken center line with an adjacent harrier line as preseribed for no-passing zones. Such no-passing markings should normally be refleetorized. Pavement-width transition lines, in themselves, are not a sufficient warning at such loeations, and should be used only to supplement standard signs, guardrails, or delineators. Approach to an Obstruction Pavement markings shall be used to warn of the approaeh to a fixed obstruetion within a paved roadway. Obstructions within the roadway are hazards that should not 1)(' permitted to exist if avoidable, but where they eannot reasonably be eliminated everything possible should be done to prevent vehicles from colliding with them. An obstruction may be in the eenter of the roadway, in whieh case all traffic must keep to the right of it, or it may be so located as to be between two lanes of traffic moving in the same direetion. The markings in either ease must be designed to defleet traffic away from the obstruction by a diagonal line or lines of unmistakable meaning. Obstruction pavement markings shall eonsist of a diagonal line, or lines, extending from the center or lane line to a point 1 foot to the right side, or to both sides, of the approaeh end of the obstruction. See fig. 25. The length of the diagonal markings should be determined by the formula L = S x W where L equals the length in feet, S the design speed in miles per hour, and TV the width of the obstruction in feet. 110 L~ L Figure 26.-Typical designs for turn markings on pavements. 112 rIanl no case areas or shall the diagonal line .50 f"eet III urIJan areas. be less than 1;")0 feet in length in ruIf traffic is required to pass only to the right, the diagonal line shall be marked to the right and shall be of one of the follO\'.:.ing designs: 1. A normal broken center line flanked by a solid barrier line, as specified for no-passing zones. The barrier line shall extend along the center line in adnmce of the diagonal line for a further distance equal to the length of the diagonal line. 2. On a roadway not marked with a continuous center line, a solid line which shall be extended, on the roadway center line, a further distance in advance equal to the length of the di- agonal line. 3. On roads of four lanes 01' more a simple continuation of the double center line prescribed for such roads. In addition, a solid \yhite diagonal line may be extended to the left of the obstruction, to outline the triangular area from which traffic must be excluded for safety. If traffic may pass either to right or left of the obstruction, there shall be two solid \\'hite lines di\'Crging from the lane line, one to either side of the obstruction. In advance of the point of divergence a single solid line shall be extended in place of the normal broken lane line for a distance equal to the length of the diverging lines. All lineH used in obstrm:tion approach markings shall be not Ie"" than 4 nor more than (i inches wide. They should preferably be reflectorized. As an added Hafeguard it is desirable, especially where traffic is permitted to ptU3H to both right and left of an obstruction, to place broad transYerse. diagonal, or longitudinal lines in the triangular area between the guide lines. aH shown in figures 25 and 29. Similar marking" are desirable at channelizing islands not so designed as to diYert traffic naturally from them. Obstruction approach markings shall be used only to supplement adequate markings on the obstruction itself. Streetcar Clearance Lines It is often desirable to mark lines on the pavement to indicate the limits and the clearance of the overhang on turning street('ars, Streetcar elearance lines shall be broken white lines, with Hegment" and gaps of equal length not exceeding 2 feet. They shall he not Jp"" than 4 nor more than 6 inches \vide. On curves of short radius it is necessary to usc verv short dasll<''' and spaces, to preserve the appearance of ~ontinuity in' a bro\';'('ll line, Turn Markings :\larkinp;s to restrain drin~rs from starting left turns befol'(' reach. inp; the intersection, or to guide turninp; vehieles, are sometimes used at intersect,i,(ms. Such markings han~ not been satisfaetorily stand. ardized, but if use~ they sl.lOuld b: so desig~lCd as to indicatl' the prop. er course for turmng vehIcles "lnthout bemg needlessly COllllUiing to through traffic or traffic makinp; other turns. Typical designs are shown in figure 2G. Lines used in turn markings shall be hroken \yhite lines. !lot less than 4 nor more than G inches "lyide. As in the case of street car clear_ ance lines, they Hhould be made IIp of Hhort dashes and short Rpaces. Transverse Lines Because of the 10\\' angle at ,,"hich pm"ement markings are \'ieWed from an approachinp; "I"ehicle it iH necessary that all tnms\"erse lines be proportionately \yidened to giYe visibility equal to that of longitudinal lines, or to ayoid appan'nt distortion where lonp;itudinal and trans_ verse lines are combined in symbols or lettering. This applies particularly to Stop lines, cross-walk markings, railroad-crossing mark. ings and word markings. Particular attention must be given to the maintenance of trallHverse lineH which, because of their position on the pavement, are subject to constant wear hy en'I".\' vehide that paHseH. Stop Lines Stop lines (or Limit lines) should be used in both rural and urban areas only where it is important to indicate the point hehind which vehicles are required to stop in compliance ,,'ith a Stop sign, traffic signal, officer's direction, or other legal requirement. Stop lines shall be solid white lines, not less than 12 nor marc than 24 inches wide, They shall extend across all approach lanes, usually to the center line, On urban streets where speeds arc not high a width of 12 to 18 inches is usually sufficient. Stop lines, where used, should ordinarily be placed 4 feet in adnmce of the nearest cross-walk line, In the absence of a marked cross walk, the Stop line should be placed at the desired stopping point, in no case more than 30 feet or less than 4 feet from the nearest edge of the intersecting roadway. If a Stop line is used in conjunction with a Stop sign, it should ordinarily be placed in line with the Stop sign. Howeyer, if the sign eannot be located exactly where vehicles are expected to stop, the Stop line should be placed at the stopping point. The word STOP shall not be placed on the payement in advanee of a Stop line, unless every vehicle is required to stop at all times. 114 Figure 27.-Typical urban pavement markings, showing center lines, lane lines, stop lines, cross-walk lines, parking-space limits, and route markings. Cross-Walk Lines Cross \\"tllks should he marked at all int(']'"eltions \ylwl't, thel'l' is material ('onfli'fot hetween yehi('ular and pedestrian moyemE'nt. :\larkl~d (TOS" walks should abo he pl'Oyided at other appropriate point" \y!Jne there is "uhst ant ial ])('de"t rian mo\"('nwn1, a" at long loading isla nds. or \yhere pedestrinn" an' permittP(l to ITO"" I)('t \ypen intel',,(~(t ion" or \\'he1'E' pedestrian" ('ould not olhen\'i"p 1'('I'ogllizp the ]lrOIH'1' pla"l' to (']'oss. ('ro",,-\yalk line", in hoth rural and \lI'han an'a". "hall 1)(' solid \,hite line", mal'king holh edgl'" of tl\(, (TO"S \\alk. Tlll'~' "IUlll he 1111\ less thanJ nor more than 12 inl'lll's I\idp (tig, :.tll. If no alh'aJH'l' ~tll\lline is pr()\'idpd. it nla~' \)(' de,sirnhk to in(TI'a"e the \\idth of thl' ('ross\I',llk line on the appmal'h "idl' to :1" nH1I'h a" 21 inl'!w", ()nllrhan "tl'eet". Iyhel'e "peeds an' I'dati\'pl~'I()\y, a \\'idth or Ii 11\('!leo is u"uall~' :lIlioq\\a te. 'I'll(' \\'idth of the (TOSS \yalk het\\l'I'n ('I'O""-\\'alk linl's i,s US II,t1ly c1I,\('1'l1lilWd h~' t hl' \yidt h of thl' "ide\Yitlk" so ('OIl1l('('\('d, Tit, \\iclth "hall in no ('asl' 1)(' k"s t h:11l () fl'pt, To f:lI'ilitnte ]H'llio"trian ('oopl'I':t1ion in tralIi(' l'egulatioll, ]H'dl',stl'ians "llOuld kno\\' exa('tl~' \yhe1'(' tlH'\' an' to (Tnss tIll' ,st 1'1'1'1, and.;iliJ\dll feel n'a"onah1P sl'l'llrii~' not only again"t \'(,hil']ps :lppl'o(\I'hinll ! 11<' inter"e('tion, hut a1.so again"t those tU1'lling within it, :-,ingl(,-lil\(' ITOS,"- \yalk marking" fail in thi". and :\\'(' st 1'Ilngly disappl'o\'('11. T\\o lines are n('('l's"ar~' to ddinl' 1111' I']'O",,-\\,:tlk an'a, and "IHllild :illl;I\S lit' noed, Route Directions .\s a s\\pplenwllt to standard roule markel'S. or \I'IH'1'(' dlll'I,tions cannot he sati"fal'torily indi('atl'd h~' an~' other n1l'im.~, "]H,(,j:11 dirl'l'tional marking" ('an sometin1l',-- Ill' l\.,-;ed on the pa\'l'mpnl. Tli('~(' nU1~' con"ist of (ml' 01' more alTO\\'", \\'ilh or \\'ithout 1'0\111' nUl\l\)('l's, in thp ccnIN of tlll' lane, .\ t~'pi('a] example i" illnstl'at"d in ligll\'(' '27, Din'('t ional markings ,--hall ])(' white in ('olo!'. Approach to Railroad Crossing Pa\'cment markings ('onsisting of n I'ro"s. thl' \1'111'1''' lUt it no- passing I'l'nler line, and ('I'rtain tl'an:-\'('rse liIH's ,~h:tll li(' pl:\(,pd on all pa yed approal'h"s to railroad (')'os:-ings, ex('"pt ;\ \ nUlior :-idings ~ "purs or in ul'han an'a" \\'he1'1' olh('1' protl'(tim} is al'!'ol'dl'll. Swh mark- ings :-hall be \yhite eXl'ept for the no-pas:-ing ]li\lTi('r lilH', whil'h should prefE'rahl:v he yello\\'. These marking" "hould nOrIll:dl\ ])(' refle('\orized. The design of railroad-l')'os:-ing paypnH'nt l11ilrkin,gs shall bp essell'", tially as illustrated in fignl'l' 28. Thl' ,,~'mhol nnd Il,t t('1':- arp elongated to allo\\' for tll(' loll' anglE' at \\'hil'h they an' \'iel\pd, , dt '''hill' these markings haye nlltll' as a nWillls of n t t rtH'ting the. tl'ntion of tilt' dri\'()1' to the pl'Oximity of a I'nilrlJild gradp cr0ssi4 IHi hf'('ause the:,' are distindin'I:,' differpnt from all other IHlYP!11('nt murk ings, (hey aI'(' only auxiliary 10 nIP standanl signs or signaL- whil" must I>e inst al1('t1 in e\'('r:,' ('as(', Parking Space Limits 'I'll(' marking of pan s(reet:-; tends 10 1'1('\'pnt elleroa<'llllwnt on fin' h:"dranl zones, jlll:-; :-;(op:-;, loading Zl>"('S, approacll('s \() ('Ol'ners, and ckaralwe space:-; for islands, Such Pi: t'king :-;paee limits may he indic a1ll1 exll~nding into the rO ('Ollll('(,ting the Sll'('('\ ('Ilib of the:-;(' ])('rpendicu1:lr lines. indi('<1( in/.!: the outsidp I>oundary of t hi' P:ll-b:ing Z01le, Th(, W!W may 1)(' di\'i(kd into stalls I>y the use of litH" ])('1'!lendi('ulal' to til(' ('urI> and so "p;j('ed lhal e, Illay \)(' p1:lced at tl\(' end of c:l<'h,,: 11 line, in plaee of thc c(ltltinuous line cxtpnding' the \('ngth of (II\' pllrking ZOIH', See figu 1'(' 27, The marking of is(alb i:-; (':-;IH'eially hell('licial \Y!\('re p:ll'kir,,", meters are u:-;('(I. .\n/.!:k parking i" g(-nerall:,' no( desirahle, t!tough ()l'easiollillh' it lIlay he justified Iinl',--. 11", I""" than 4 nor mOl'e than Ii inl'!lPs \\'idp, Word Markings "'on I marking" on tlw pan'nH'nt may he u"l'd for IIii' ])urpose of guiding, warning, 01' n'/.!:ulatin}.!; tralfie, They ",hould 1" limited to as 1'(-\\' \\'ords as possihle, IIl'\'er moJ'(' than thre;-', "'01'11 markingiS shall !\()( he niSed for mandat(lr\ Illl'ssages except in IiUpport of standard sign". TIIP:" slwlJ he \\'hitl' ill ""lor. The 1l'lIeriS should Il(' greatly elollgakd in til' din'diem of traffir mo\'pml'nt h('('alltw of the 10\\' angle at \\'!rieh th,'\ :11'(' \'ie\\'cd hy 3Pproaehiug drivers, On high-speed road", ('spe('ially wlwn' t ralii" i" 11(':1 \'y, messal(es tJ more than one line an' umlesirahle and "hould l!.flli'l':llly be :l\'oided. It is diffieult to read and understand a nwss:ql;l' \\hen the \"ords ':: neeessaril:,' spn'ad oyer ,"'0 /.!:reat a distalleE' that tl",\ are not allleF:1 at (l!le t illW, liS Where pn'Yailing 1mlnc ~pepds arc grcr llsed, ;;; fpet or !l101'(' in lwight: and, if the !l1essagp con"ists of morp tlHln Oll(' \rord, it shollld read "U])," i, c" the first mml ShOllld 1>e nettrest the dri\'pr,. Thr space hetm'en Jines shOllld he at lea,s1 fOllr lime" t he heigh t of the ('hamC'ters, On ilIP olhn hand, ",here ))J'e\'ailing 1ratfic s])eeds an' ;~:) milp,s ))('1' hour or less, i1 is ])o"sihk to USP smttller ktters and 1ll1l1l(,],e alTangpd 10 ]'('ad "dmn!." i, c .. \rith the fir"t \\'ord farthest from 111(' drin'I', The spa('ing het \\'('pn the lines should Il(' eqllld to 1hI' lwight of the charaders, The \\'onl STOP "Iwll Jl('\'(']' llP llsed Oil the pan'!llcn1 in ad\'tllH'e of a StO]) line, lin less e\'('r,\' \'ehip]p is )'('quirpd 10 stop nt all times, Curb Markings for Parking Restrictions Curb markings nla~' he llsed to sho\\' \\ here ])tlrk ing is proh ihi t ed :11 all timps, They "holl]d not lw ll"ed e,,('p])1 (J)) ('III'hs along \\'hich parkin/!: is kgally pmhihited, either hy g('lwral ordinmH'e, as al tin' hydrants, adjacent to conwrs, and oppositc loading i,slands, or hy t!lt-' erection of stnndnrd no-parking signs, Thp cmb marking shall }w of a solid ~'pllo\\' color, ('O\'pring the face and top of j he curh, E"prrience has sho\\'n thttl the pllhli(' does not easily llndcrstand a color code \\her8 several eo]or" arp m;ed in ('\Irh marking to indicate' different types or dpgrpes of parking rest riet ions, Curh marking" are' accordingl~' !'l'commcw)ed only 10 shOll' that parking is prohibit ed a I; all times, OJ her rest rictions should he ShOll'll b~' st andard parking signs, 119 C OBJECT MAHKINGS Application of ~bject Markings Ph~'~i('a] o!J,.;ll'l1('tiun" in ur n('ar 'I mad\yay that ('lln"litull' "1'ri"ll> Iwz,lI'Ib to traH11', in('!ndillg in~tall,ltiun" dl'"igll('d fur tIl(' 1"lIl( rid 'If 1rnlh(', ,.;halll)(' ,ld(''1Ualp!y markpd, T,\'pil'al oh"tr\ll'lion,.; of thi,.; ('har:\('I('J' al'l' hridg(' "upporl,.;. 11I11\IU11l('nl". I ralli(' i"lanl!";' 111'al'llIl ur "ignal ,.;upporl~. ]'Iading i,.;lalll!". I'ifniI'ad(',.; 1(1 I'!o"(' road". railroad and dra\\'hridgp gall'''. pnd po"t.~ 1>\ liarI'U\\' hridgl'''. ulId('rpa"" pi('r" alld ahut 1lH'llh. ('\\1\'('1'1 ]w:lIl \\',dk "-liard rail", "igll p'I"\";, pU!('.~, 1n'('", alld m('b, :lIld ,,1 1'\1('t \\n'" 14i\'ing 1'1"1 lil'l('d 11\'('rhl'ad (']Paranl'(', ()nl\' "I!I'h il1lll1()\'alll(, oh"tl'ltl'lilln" a" hrid14(' "\\pporh and 1II'(r~"ary i"\;md,, ,.;hould h(' p('rll1ilt('d to ]'('main \\'ithin th(' rO'lIh\'I.\. I:\"n al j]\(' pn''';1'1l1 lin1(', oj)"1 r\\('t ion" an ol'('a"ion,dk pla('('d in I'il:rrhya~'., nndl'r tI\(, llli"Llkl'n hl'1id that l!W,Y' \\'i11 "1'1'\'(' a,.; aid" to 1)". ,'ontrlll IIf tr,d-!i,', ~11('h ilHallalion" inl'!ud( "i14ll,d ]H'd('"jal" ill th, ("nll'r of ill(('r"('I'\ ion,.;, "ign or "ign:d ])()"t,.; ,II railm,ld ('m""i 1112> , ::lld Iargp "mll.~hroom" hul1111l"; ill :1('li\'I' tr,dhl' an',I', Thl'"'' .~hllllid lll\ariahly 1)(' \'('II\II\'I'd fill' ,afl'ly . .I\\dgll\l'nt 1111\,,1 Ii(' (':"I'I'I'i."I'd ill tl\(, markillg IIf IIh.i""I~ I Iltl'road\\',I\' hut it ma\' hi' nut('d th'l\. ('\'I'n \\'hprl' thl'~' aI'!' lhi'("'('llr':d]~' at a ",11'( di"lal\('I' frllm til(' ma,l\\a\', marking thl'lll Il\il.\ 1'(I'\"lil "I'rillll:' ,1"i'iljplll~ ,md fa"ilitnll' night dri\'ing, Objects within the Hoadway ()h~1 l'Iwl i'lIl" in t h(' mad\y:!.\' .,,1 li\ II hi' mark!d II Ii Ii Itl,l II'."" Ihall ii\'I' ,dl('maling h\;\(,k and \\'hilp "Irip('" Thl' "trip,>, ,ililll ,Iopl' dllwll- \\'ard al ,In allg](' of L-) dq!y('(', (iI\\:1l'I1 tl\l' ."idl' Ill' it\{ ,l!l"tl'lll'litill Oil \\'hi"h tralli,' "hall pa"" TI\(, altl'l'Iwl(' ~trip,',,,~h:,)1 i", Ul\it'1Il'111 lind 110\ ks.~ lhanl iu<'1I('s ill \\'idth, Thl',\' 1I1i1.\' h, ::" 1111\,11 I"idl'r a, may hI' \l("'I'.~..;ar~' lu m:II':'I' a 14011l1 appl'ar:lI\(,(, alld 11\ \iill\\dl' ,.;\tflil'i('nt "i"i hilit.\'. dl'p"I\lliug ')11 t h( ,iZl' I\f tI\(, uh.il"'1 :ll\d ~11i'!,d 1\1' ilPPI'iI,ll'hin~ Irillli!' .\ ('\Ir1, al Ihl' ('ud of illi i"land \\u\lld ul\l 1',''1\11\'' '\ I'IP('~ of 111t11'1' thllll t I\(, -l-iu<'1\ minim\lll1 \\idt h. \\hill' iI largl' "UI'I':\I'I, ,(wit ii' :1 hrid!!(' pier. might l'l',!11il'l' "lripl'~ of l:l-inl'il 01' gl'l'al('r lIilhll d"/l('lIdill/2: 01\ it~ aJ't'l. Th( lI'idl'r '"Irip,''' ill'!' I'",.;il'r ,\lid k"" (':"])('I\"i\',> til :Ipph'. [f dll' IIh"II'\!I'til\g uhj(,(,t i" ~\1I'1i that il dl\!'> 11111 I,'nd it"l'll n'adi/1 J,lla:. to Ihl' iI]I]l1i('al illn ,)f ]ll\i1l11'd 1I1'lrkill.i2;";. I h, -11'ipll\g Illil\' II{' ,)1\ ,\II indl'l)(,I\I!1'1I1 '\Irfill'(' iltl,Il'h(,d III 1\1' 1\11\\111\1,,1 ill1llli',liilli'I~' 1U \.,\11,'(' of Ill(' ohj<.i't, sit1IiI ,\ P]ll'llPl'.lilt'l' ,"1g:U~ l I,':")0. \\' :!-I) 1j'11'1'1"1111.l!. Il'iI II',,' II) I ., I) \' or hoth Ill' til(' oh"II'\Il'1iol\ "hould a1";1) hI' \1"1'11. :Ie- ilppli,,d>i,. I:lO III ;ldditillll III 111(' 1I1;1l'kill!l> "II Ilw fat',", "I' :til llh"tl'll<'tillll ill Iltl' ro;lt!l\";I.\' 1\";ll'lIillg llf :lppl'll;1('1t tll I Ill' 1t;lz:1J'(1 "Iwll 1,(, gi\"plI II)' lilli' 1l1:ll'killg" llll I Itp pmT!llIIlI. ;I," ,1t"111I ill figlll'l' :!\l Lighting or I{etiectorization of Obstructions ,\" It 1'1'1' :III ()h,,,tl'll<'tillil lip,; ill tlt( dil'l'l,t liIll' lll" 11,;tffit,. Iltl' llI1.,;tnll'1i()]) :llld lll:tl'kill,i.!> tll('l'l'llIl ,,;ltllllld, if pll,;,;il,Jp, 1,(, illllllliIl:ltl'd I,.\' :1 r!lllld- ligltl ,;" 1(1l1.--tl'lll'1pd IIt:lt it \\"ill ;ldl'!I\I;llt'!." liglll Iltl' lll',il'l't Illil II"ill n()t Iltrll\\" ;1 ;;1:11'1' ill til(' 1";1('(' "I" Ir:lffi(' ,lppl'll;I('ltillg fl'll!ll l'il!wl' dil'l'C'- lioll, '\"11('11 fI()lldligltt illg i" Jllll pr:lC'1 ':t!, Iltp 1llljp('1 1ll:ll'klllg,; "ltmdd hI' I'tTI"'ti\'I'!.'" I'dll'I'(lll'izpd, "' l'I'r!l'C'1illg l'll:liiIl;; ,;11()ltld 1)(' :tpplil'd 1(1 tlte IIltli,'--il'ipp,; ()I' tlll'I'I' ,;1t()\lld 1)(' pl;I('I'd tlll Iltl' lll,,--ll'll<'lillll tllll' lll' m()J'(' 1:11'.12:1' yl,llll\\ rdlpl't()I''; "I' (,III,;t 1'1', "I' \'pll"l\ l'(flpI'1 iIlg Illil I llll" ;11 11':I"t 10 11Il'!1I''; III di:lllwtl'l'" Object \Iarkings on Curbs ,\!tI'III:II(' 1,]:lI'k :llld I\hill' ,;tl'ipl,,;,,ll(lltid I,:, pl;l('pd ()II til(' 1'lIl'h,-- tit :tli i,;l:llId- ItI(':l1pd ill t II(' lilli' "I" lr:tffi(' 11,,\1" Tit,,), Ill:l)" :ll,;" 1,( It(,lpfill (,n ('\11'1,-- dil'l'('th' :lhpad ,,! tl':tfli(' :11 T alld ()lbl'l iJltl'l',"('I'ti"II,-RI'I'all';(' ,,! Iltl' ()l'diIl:ll'ih' IllII Itpight til' 1'lIl'h,;, till' ,,,t I'ipp,-- "llIlltid IJI' Il'l'ti(':tI tin ilil' ('urh f:t(T" 1':ltltl'l' tll:111 ,--I"piJlg :1-- till lltlll'l' ,,11.--11'l1l'Iillll:', ,,1,- "'It I' J'(' tll(' ('111'1, i,; 1l:111Ir:tll~" d;lrk, "llffi('il'lIt ('I (iIi ;-j!1 7-1 1;7 S~l 101 II:! 1:2-1 1:1" I"" SO \1:2 10:{ II:! I')') 1:11 ;2:{ ;-);{ II IS .).-) li(; iti Hli \II J()~ 10\/ '17 :H II -lli ,"')/ fili /t R') oS!1 !I;) :.?:~ 'J.!I .j;) 11l ,)() ;"'),s li(i 7'1 7\1 K) 'J.() 'J.li :11 :{fi 41 ,"')'1 ;-)jl li;-) 71 77 '1;) :2S :u 41l -17 ;-)-1 fiO fi;-) 70 'J.:) '27 :Jl 4I -Hi ,-)'2 ,"')/ (i1 :!OO 2(11) 2110 21111 :200 21111 1!1I1 IriS 1,"):2 j:{!l Ill; IIlI !IO ,s'J. 7;"') lit) "94 " I TIll' ,... p:u'inl-':, ,\ 011 1Ill' YNli(':\! ('\11'\(' to llw:\irnlllll of 'J.()(J f('dl I."'"' f()lInd fr()ll] (])(' il'l'llllli:l' 1. I; -:20 \dwl"(' 1> i." 1111' ]pn!!! h of Clln'(' in lJ\lwln'(!::: of f('Pl :lllcl I; i::: tIl(' alj2J'!)r:II(' 1Iirt'l'!Tnt'f' in ~~~J(:L7~~I/,~~' Tlw :Id\:\[l('(' to IhL' !ir~l 11(liIH':1 r or ill of :ITl(l In til(' {w:\1 fi.""'. hilt IHlt j(, tIl(' ('111""(' ~d\()ll]d 11(- 125 Part HI SI(;NALS A INTRODCCTION Definitions lIig]l\\a~' I raHic~i!!:llttl~ i'll'lwlc ~t11 111:11l1Iall\', I!ll'i'!llillii'ldh fll' 1,1"1'tricalh' o[Jl'r;lled Iralfi(' Cfllli ml d,'\'iCi',~, 1':\I'i']>1 .,igll'" h~' llliic!J Irltllil' i~ wal'lll'd ;11' i, din'I,tl'd to Illki' ~OIlH' ~I)('('ific 1ll'lilllL .\ glll.';';:II',\' fli traffic ~igllal li'rm,; lIill 1)(, IOlllld ill a]>IH'lldi:\\, ralue of Signals Thl' 1I'ltfli(, ,;i!!:II:t1 i.~ cdt''';II'ialllr:tlfic, Iki'llll";i' of it, arl,itl'ary Ill' trafficin"llt'l'd a,;,.;i!!:I1IlH'1l1 of ri!!:hl-llf-I\'a~' Ifl Ihl' "arioll"; 1ll0\'1'1lH'1l1, nf'cr~sary a1 illtprspi,tion.~ ;In,1 at (11111'1' ~tn'pt 111111 liig;III\':I~' 11)("llillll~, till' traflil' .;ig;llal e:\pr1..; a ]>mfolilld illfillpllI'p Oil lr;dfil' 11011', ] II lllo~1 ('asps, a ,.;ig;llal ill,;tallation \I'ill opl'mtp 'iUile dl'finill'ly "illH'r to the all(,; 10 hi' ll1adi' in tJ1(> ('ol11mk (nf'ckhack,; ari' of \'ahli' not only 10 tIl(' parI il'ular in,;t:dl:tljoJl ('on- eemrd hut in t Itl' KI']p('lion of proppr I'qllipnWnl aJld oppl':lting plan,.; for futul'(' in,;tallal iOIl~ as \\'pl1. Highway t raffi I' ,.;ignals, pro])('rl~' op(l'alld, UKllally kl\'p mil' 0]' 111011' of tIl(' follO\I'ini!: ad \'[1I\t agl'';: 1. Tll('y pro\'idl' for onkrh' 11l()\'('lllpllt of tndtil', 2, Tll('~' rpdul'l' t hI' fn'qll(';H'Y of ('cr1 ain 1ypp,; of ;l!'l'idpllls, 3, TllP~' ('an 1)(' l'oordinaled to prm'idc for i'oJltimlous or l\('arl~' ('ontinuou,; IllO\'pmcnt of traffic at a definite ,;ppcc! along a gi\'('n rou t (', 4, Th~'y ('an hI' {!Sl,d to l'ol1trol ,;peed on through highll'ays and malll route,;, 5. T~ey ('an hi' u,;('d to intel'l'upt hpa\'~' traffic' at interntl~ to prr- mit other traHi(,. ]1l'de';1rinn 01' \'(.hic:u]al'. t () n08S, 127 G. They represent a considerable economy, as compared With manual control, at intersections where some defini if' mean S of assigning right-of-way first to one movement and then t anothg is required by the volumes of vehicular and pedes~ trian traffic, or by accident conditions. There is a belief among laymen and some engineers that traffic sig_ nals are the answer to all traffic problems at intersections. This has led to their installation at a large number of locations where no legiti_ mate factual warrant exists. This stereotype plan of imt:dlation should be avoided. Many signal installation:-;, even though warranted by traffic and roadway conditions, have been ill-designed, ineffectively placed, improperly operated, or poorly maintained. The consequences have often been excessive delay, disobedience of signal indications, use of alternate routes, and, often, increased accident frequency. The same difficulties are often found ,vhen signals have been installed under conditions that do not satisfy the minimum warrant8 set fort h later on in this manual. A careful analysis of conditions at a large number of traffic :-;ignal installations, coupled with the judgment of engineers with long experience in the 8ignal field, has provided a series of minimum ,varrants that define the conditions under which a traffic signal installation may be justified. These \varrants are p!'psented in this manual for the 8everal signal classifications. Separate valups are given for \nurants for rural and urban areas, in recognition of differenc'es in the naturp and environment of traffic in these two general area classP8. Drivers in !'Ural areas arp ('cmditioned to relatively light traffic, and intersections \vith only modPl"ately heavy traffic' volumes have greater' potentials in terms of congestion and hazard than do similar intersections "'ithin a ('ity area \rhere heavier volumes predominate. An urban area is here considered to be a metropolitan region having a population of 5,000 or more. All other places, for the purpose of these warrants, are regarded as !'Ural areas. Standardization Because of the increasing range of traffic circulation, it is of primary importance that there bc national standardization of those feature" of traffic signals that effect public participation in traffic mo\'Cm(']lt. De8ign, application, location, and operation all lend themRelves to a certain degree of standardization, and standard8 for 8uch features :1re presented herein. The increasing use of and need for train-approach signals and automatic gates at railroad grade cros8ings heighten the importance of standardization of this type of equipment. The principal features of 128 design and open.lt ion that haw' .lwen .standardized by the ASi:iOcia tion of AmNican HaJlroads are set jorth In the pOl'tlons of the text deal. g with train-approach signals. III Legal Authority Traffic signal indications \\'ould he unenforceable if plaeed hy other than public authority. l'nottieial trattie signab should be legally prohibited in all jurisdictions, The erection of signs or other de\'iees that hide from vie'" or interfere \\'ith the dfcetiveness of any t rattic signnl should likP\\'ise be prohibited. It is imperati\'e that traffic signal indieations be Htrictly observed and enforeed. Articl(' III, Seetions 31 through 38, of A.d 8,)-J. of the :\'m'emherDecemher ] D5:3 Session of the (;eorgia (;eneral,\HHf'mbly provide lrgal anthority for installing and enforcing restrictions of mm'enwnb of traffie hy use of :'iignab, and other traffie control devices, Seetion 32, Articlc' Ill, of "\ct 8;)-J. prOl'icb., that "All trafhc ('ontl'ol devices shall conform to tho:'ie adopted under the authority of Seetion 31," \\'hieh :'ieC'1ion reqni]'(~:'i that the State' High\vay Board shall adopt a manual and :'ipeeification:'i for a uniform Hystem of traffie control devices for n:'ie upon all higl1\HlYs \vithin this State, Prior to the mandatory adopt ion of this manual a number of trattie control signals not meeting the requirements and specifications of this mannal had lwen installed in some areas in the State. All :'ilH'h signals shall be replaced as soon aH practieable. \Vhen a major repair is necessary, on any signal, snch as motor replacement or replacement of signal head, complete replaeement :'ihall he made. and only "'ith eqnipment that meets the reqnirement:'i and speeifications of thi:'i manual. Any installation of a traffie control signal made sub:'iC'quent to ~Ian'h 12, 1\)54, shall conform to the requirC'mC'nts and specifications ineluded in the J! anllal on l'nUurm Tra./fie Control /)CI'z'CI'8, adopted hy the State Higlmay Board on :\Ianh 25, 1\)54, or amendmentH th(']'C'to as may thereafter hC' adopted b~' the Hoard. Hefereme is made to Act 8;)-J. (Georgia La\\'H 1g,):). :\' o\'emherDecC'mber SeHHion, pagE'H ;),)(i-H2:rl for more eomplete information. Classification In the elasHifica tion of t rattic signals i ha t f01l0\\'H, tlJP distinetion iH made on the basis of operating function and noi tbe traffie signal unit itself. It is common praetiec to usc the term "signal" to describe the complete inHtallation, and that practice will he foll{med in this mannal. IIigl1\\'HY traffic signals are daHsified as foUo"'s: 1, Traffic control signals (Stop-and-Go) : (a) Fixed-time signals. (b) Traffic-actuated signals: (\110) Full traffic-actuated signals. (2) Semi-traffic-actuated signals. (3) Speed control signals. 2. Special pedestrian signals. 3. Other special traffic signals: (a) Flashing beacons and signals. (b) Lane-direction traffic signals. (c) Traffic signals at drawbridges. 4. Train-approach signals and gates. (a) Flashing light and \vigwag signals. (b) Automatic crossing gates. 130 B -FEATURES COMMON TO FIXEDTIME AND TRAFFIC ACTUATED SIGNALS General Aspects of Signals The featnres of traffic ('ont 1'01 ,.;ignal,.; in \\"hil'll I'ehide oppnllor,.; and pede,.;trian,.; me interp,.;tpd, nall1pl~. tlw location. design. indication,-. and Ipgal signifiearl('(' of the signab Ihell1sdns. a )'fiden t i('al in fixedtime and traffic-al'tna t I'd ,.;igna /.-. tlw difTerp!H'(' h\'tIH'pn thC' two 1."IW"; being in the mechanisms that op('nll(' them. :-\talHlardizalioll in those dE'sign faetors that affect t 1)(' namc to he l'0I1trolJed is e'-lweialJy iI1lpOltanl, ThE' sC'(tions of this subdivi"ion ('ontain alJ standards and requirement" of this !WIIII'(' thai an' eqnally applicahle to the ill'o typP" of sign:l!s named, :-\tandards applicahk to Illil OIW type, inl'lndillg design fc:tiurps and mPlhods of operation. arc pn',;('nlpd in .';IJ1l,.;eqlll'nt S\lbdi I'i_ions, Design for Future Needs Tmtfic conlrol eqllipml'nl shonld :d lVay.- he pnrdw,s(d Ivitll the 1'11- ture in mind, Flexibility 1l']ridl may no! inllllPdi:lll'ly he' con"idered nel'pssan' Il'ill often hl' found de,;irahj(, Ivithin thl' life of 111(' C'Illipmellt, EqllipnlPIlI thtlt Ivill gil'(' long et'fectin life Il'ill :dllltl,-t ~d\\:\,I''; pro\'(' an ('conom~' ('I'en if tJlt' first ('o,;t i" lllod('r:Jtel." higher' than that of equipmelll of inferior qllaliiy. Number of Lenses per Signal Faee Each sign:d f:u'p shall Iwl'(' nt ]I'asl 1!t)'(,1' Il'll,;('S ),l'd, Y('HOII, and green, It 1ll:II' 1l:II'(~ additionnl Ien,.;I',- a,; illdit'~lt(:d 11I'l'('i 11 , EXjlel'ip!]('(' Ita,- sltOll'n tlw t thI' ~'('lloll' illt lit'at i, 11I ,-('1'\'(''; S('I'()':1I iIll- port:ml trafiic control function" Ihat (':llIIltJI ,';:lti,;f:l<'to)'ily h(' "':(']'I'I.'d by a tII'O-Ie!I'" ",i,gllal fal'p, Thesp a)'(': I. Tltl' ~'('IJ()\I' ,;igll:ll ac(,; :t.- a cU"ltit>ll at t \1(' ('lld of t It(' (;() illt('ryal and \1':lJ'IIS :qlJJI'oill'hing tl':lfiit, of a <'Ilang(' ill ,-ignaJ indie:ltion, ,) ('aI's Il'illtin all illll')',-pl'tion 0)' otlll'), ,-ignnliz,d an'a, a,S Il'ell a,; tho,,(' nppmac!lillg ,_0 dos('].I' tltal to stop \I"l1dd h;' liaz:lrdolls. a)'(' gil'('ll :Ill ojl]lO)' I 1I1lit Y 10 c!(':l)'. 3, Flashing .\'eJloII' i" imjlortallt a,- a c;lutioll ,;i\;ll:d 1I'II('n 111(' ",ignal is not I!('in,g o]lcnIU'd :1" ;I :-,lop-:llld-(;o d('I'i('(', . ArrOlI' indica1ions ,;h;lJl hI' ,.;hOII'1I at in11'r,-eciiolls whc)'(' "igll:d,s for individual tUl'Ilillg 1ll00'('IIWllis a)'e ])}'()\idC'd. Th,sl' inc'ludl': I. f'traigltl-thl'llllgit al'J'OII. 2. Left-t Ill'll a ITOIL ~3. Hight-lurn anOl1 for thp cOllt)'o] of jll'dl'snian" Illay ;lbo hI' added to paclt sign:d I:-j I Color and Position of Lenses All !en",es ::;hall Iw ananged in a "tmight and prderahl~' YNt inti !il\<' and "hall 1)(' in tI;~ following o]'(kr, from lop to hot tom or from ]('1'1 to right: J'osdiol/: .) Ii -, SiUllol indicotiol/ Hed YdIO\\ ( ;1'('el\ :-1t migh t-t hrO\\ ,1lTO\\ r,dt -turl\ arrO\\' I~ight-t.\lrU alTO\\' Wait (or Don't Walk Walk ..\11 arrO\\'" shall he green on an opaque baekground. \\'alk-\\'ait lenses \\'hieh are il)('orporated in ",tandard signa] h)('p", shall hi' ,f the design de,'inilwd in Gpnpral Dp,'iign Hpquiremenls, The colors rpd, ycllo\\", ,md grepn ",hall eonform 10 t hp ad,inslahleface lJ'Hffle con1rol "i~,!;lwl head standard" of the Institutp of Traffic Engine(']'",l appro\'(>d ac' an AnH~ripan :-1tandard hy Ow .\merie;11\ ~tand ard", A"s()ciation (I) 1O.I-HH2). In addition to the foregoing len"e". "pecial Iwde"trian "igJwl", mOllntpc! apart from the traffie :-iignal head may he prm"ided as s!)('('ified in anot!wr section. Meaning of Color and Arrow Indications . ('0101' and alTo\\" indi('ation;-; in traffic ('ontro! "ignal" "h"ltld have the meaning", a",eribed to them in thi" ",petiou and lIO othpr lIwanings. In no ea"e, hO\\"(;\'pr. "hould a dri\"er he permitted to en1 PI" or proceed through an intersection \\"ithoul due regard for til(' "are!y of other per;-;on", \\ilhin thp inter"ecjion, regardk"" of "ignal indi(';ll ion". Sati:,f[[ctory result;.; from traffi(' signa] operation l"I'quin' a uniform under"tanding of their color indication;.;. Tho"e hcnin ~pt forth are in [[econl with Artieje Ill. :-1cction :32, of Act 8;)L TIt( :-imultaneous illuminil hon m overlapping of different eolm indje[[tions. except where green arrows are shown 10gpther with the ejrcular l'(d indication, or where pedestrian len"e" are irwolved, is not ]"(>(oIl1mcl1llpd. This "eetion applieH primarily to traffie control "ignal" at interaec- tions, but appropriatp intprpretation can be rpadily made for use of signal:-< p18e\yhcre, such a" at ;.;('hool no",singi:i, fire "ta1 iOlls. and draWbridge;.;. The meaning" of the indieatio!i":, \\'hieh should !H' j hus pn'scribed by law. are as follO\\"s: -', it dj".' ,Pt'I' "lgtl,tI 1'111'1' ('011- fll,illil Itl'> fl'l'IIIII'III!I' Ill'i,('11 1l'''lIl III(' 1111"11,1' "I' I hi, il'II' \\'/11'11 IIii' 11'1I~lh III \'1,11,,1\ It,hll'll'-I'\,'III'IIIII'I' 11111'1'1'111 i, I'''IT('!'I, '1IId III(' ,llllld:\1'1! 1I11'~III,lll\.!, ~Ih"\,, dt,,,"I'il)(,cI h \.!,1'III'I'~tll\' ,,1"'I'n'l,d 1II"'I'>,~III'\> flllll'- tillll' (If 1IIII'IIIIIg 111111 ,'!I':ll'illg IIII' 1111"1','1'.'11"11 III'" PI'l'i.II'llli'd I,\, 1111.' intl'nll], teady Hecl"!"1I1 (/ "'''/O!i'': 1, \'('hil'II]III' Il'lilli .. flll'lll~ IIII' ',gll,iI "II:lII'!1l1' 1111'111'1' 1'lill'I'III\.!, IIii' "I'II",~ 1IIlIk Ilil till' 111'1/1' "idl' "I' 11\1' ]II!"I',,(,.'I illil 'II', II' "'1111', 11\1'/1 1,,,1'111'" "llll'l'1ll~ 1)11' IlIt"I',,(,.'IIIIII, :llld ,hldl 1'1'llllllll >1111IIIIlIg II!II II a ~1'I'1'11 ,i,t!,lIld i" ,,!I()\\'II " \11 P,'d(',ll'i'"1 flWill\.!, "11"'1 "igll~iI "lildl "/111'1' IIII' 1''':II!1IU.'' lilltii Ihl' 1!:1'I'1'11 Ill' "( ;,," i,,,,; ,,,hO\\'1I :iI"III' 1IIdl'''" U ,'I'I';[I':t!I' \\:llk illlli(';I- 1il III i" ,,1i1l\\'11 ('lIl1fll"jllll '11111 "I'l'ioll" h:lz:ll'd 1'I''';ltI! I' 1'0III 1:11''' of 1111lf"I'IlI "llI'dil'III'" to l'i,d "i~llak '1'111' I"'d illdi"ulioll ,,!loltld :1/1\':1\',; 1111':1/1 Ihul "U"'I \'('- hil'JIl hilall ,lop Itlld "lwll lIot !l/'o"I'"d f:t1'111I'1' '1IIItii U (;" "j~llul :lp- !l"al'" 111"1'''" ")II'1'ili"lilh' :llIthol'iz"d II\' 11111' III' 1/11' :l1I"i 11;1 1'\' illdii'1l1 iOII" \Il'~:ril'l'd 11l'1()\\,' , , ifill /l'it!, fil'l I 1/ 1/1'1'1111': 1l1:1~' I. \','ilil'ldal' 1I'Iillil' f;willg ""I'1i ,...;i\.!,IWI ..alii iOll"ly ('III "I' 1h(' 11I11'/''I'I'liOI I "I"Y 10 Illllk" til<' Ilw\,(,IlI,,"1 illlli('at"d 11\' ,'llt'h :,/'- 1'11\\, hilI ,..;hal! \'i"lcially where irreregular types amIf'orms af'mtersertlO. nH are m. voIved . The trend tmnm] the use of signals suspended dirertly over the tra\'eled \yay, either on mast armR or on a span wire, has IJPcn increasing in recent years. ThiR loration is especially effective at rural intersections where speeds are high and maximum prominence for signal indications to drivers is needed. Another fartor contributing toward more frcquent use of over-thp-roadml,V signals is the growth in brilliance and color of illuminated adycrtising signs in shopping areas. Where such background lighting is likely to be a serious hindrance to the effective display of traffic signal indications consideration should be given to the mast-arm or suspended loration for at least one of the signal-face locations. Pedestals in the roadway to carry signals are driving hazards and are not recommended, despite their obvious advantage as conspicuous signal locations. This is not intended, however. to preelude the use of signals on pedestals or posts within the area of properly dpsigned ehanndizing islands or in t he median strip of divided roadways. Where physical conditions prpvent a vehidp driver from having a continuous vie\\' of at leaRt one signal indieation through the :300 feet immediately in ad\'iUlcP of the Stop line, an auxiliary signal location shall be used to providp this visibility. If physical eonditions make it impossiblp to provide any location whieh ean bp seen for 300 feet, a caution Rignal or a Signals Ahead sign shall IlP erected in a suitablp position to warn approaching traffir. Height of Signal Faces The bottom of the housing of a signal face shall be not less than R feet nor more than 10 feet above the sidewalk or, if none, above the pavement grade of the center of the highway, except that where vehideR must pass under a signal housing, the height to the hottom of the hOllRing shall be at least 141~ feet but not morp than 15H? feet above the roadwa)T surface. ~faximum yisihility is the guiding prineiple in def~iding signal height. Signal faces should be high enough not to be obstrueted unneeessarily by passing vehides and pedestrians. On the other hand, especially in urban territory, the signal faees Rhould bp low enough to he within easy range of tIl(' average pedeRtl'ian's and \\'aiting motorist's eyes. Grades on approaching Rtl'epts may he important fadors in determining the mORt effectiyp hpight. The clearance required for 8ignal hou8ing8 mounted over the road- waY is con8i8tent with general highway requirement8 for overhead structures. pointing of Signal Faces - Each signal face 8hall be so adjusted Yertically and horizontally that its beams 'Yill be of maximum effectiYeness to t11P approaching traffic for ,Yhich it is intended. In general, signals should be pointed 80 as to haH' a maximum dfec- tivenes8 in the u8ual p08ition of approaching drin'rs at a distalH'e frum the Stop line equal to the ayerage distance they mJUld moYe "'hill' reacting to the Stop indication and stopping their vehicle8. The in- fluence of CUlyeS of grades should also be considered in the aiming of signals. For an average urban intersection where the normal 8peed of ap- proaching traffic is 25 mile8 pel' hour, the point of maximum effectiveness for aiming the 8ignal \\"Ould be at the height of a driver'8 eye8, about 6 feet to the right of the eenter line of the paycment and about 75 feet baek from the Stop line. Frequently poles on which signal faces arc installed arc not exactly vertical. Brackets or other mounting fixtures used 8hould be of 8uch a design that it will be p08sible to adju8t the signal face both horizontally and vertically through a considerable angle. Location in Relation to Curb Line Signal face8 mounted at the roadside 8hall be located as near a8 practicable to the curb line of the street wh08e traffic they control. They should be about 3 feet from the crOS8 walk of the intersecting street, or from the plaee where a cross ,Yalk would normally be located. A signal or its support 8hould not ob8truet the cross walk. In order to present to the driver a maximum of effectiveness, a post or bracket-mounted signal face should be kept close to til(' curb line. However, for the protection of the equipment from damage by passing vehicles, it i8 not cle8irable that any part of the signal head extend within 1 foot of the curb line. Location in Relation to the Pavement or Traveled Surface Hegardless of the street or highway eros8-section de8ign, a 8ignal face shall not be more than 10 feet to the right of the pavement or tra\'eled surfaee. In the case of rural higlnnty8, the 8houlder \\'idth may create a problem in signal location. So long as the signal faee is not more than 10 feet to the right of the pavement and is not hidden by foliage or other sight ob8tructions, it should be 8atisfactorily yisible. Experience indicates that signals mounted on poSt8 near the eurb in urban areas are generally effective although, "'ith parking at the eurh, the right side 141 of approaching vehicles is normally about 12 feet laterally from such signals, which roughly corresponds with the distance specified above as a maximum. The vehicle operator usually gives his major attention straight ahead, and a signal indication more than 10 feet from the edge of the moving lane is not likely to receive proper attention. This rule has important bearing on both first cost and maintenaIH'e outlay, for if a signal can be post-mounted within 10 feet of the improved surface, the advantages of lmv mounting height and simplified maintenance result. However, if the shoulder width or some similar condition requires that a mast-arm-mounted signal or a centersuspended signal be used, costs are increased, mounting height is greater, and maintenance is more difficult. Removal of Confusing Advertising Lights or Display of Unauthorized Signs, Signals or Markings Section 38, Article III, of Act 854, Georgia General Assembly, approved January 11, 1954, provides: "(a) No person shall place, maintain, or display upon or in view of any highway any unauthorized sign, signal, marking, or device which purports to be or is an imitation of or resembles an official traffic-control device or railroad sign or signal, or which attempts to direct the movement of traffic, or which hides from view or interf2res with the effectiveness of any official traffic-control device or any railroad sign or signal. This shall not be deemed to prohibit the erection upon private property adjacent to highways of signs giving useful directional information and of a type that cannot be mistaken for official signs. "(b) Every such prohibited sign, signal, or marking is hereby declared to be a public nuisance and the authority having jurisdiction over the highway is hereby empowered to remove the same or cause it to he removed without notice." Provision for Future Installation Signals should always be installed so that future traffic growth and other later requirements can be as readily met as possible. Outmoded, worn-out equipment and materials constitute serious handicaps to extension or improvement of existing signal systems. The type of mounting selected, the choice of wiring and accessory equipment, and other seemingly minor details of a signal installation play an important part in the reliability and effectiveness of signal operation during their service period. These elements should be carefully chosen for the particular duty they are intended to perform, and with a view toward obtaining uniformity and standardization of equipment, so that exchange and replacement operations will he simplified. 142 Types of Mounting for Signal Heads Types of signal-head mountings include the following: 1. Alongside the roadway: (a) Posts 8 to 10 feet high. (b) Short brackets attached to poles (at same Ileights). 2. Over or in the roadway: (a) Long brackets or mast arms extending from poles off the roadway. (b) Cable suspension. (c) Posts or pedestals on islands. Group 1 has many advantages, including simplicity of design, ease of access and maintenance, and better conformity in height to the needs of traffic. Of the two types in this group, post mountings are preferable. Where an existing pole is at the position desired for the signal faces, however, it is generally used. New poles may be installed to provide necessary support and clearance for overhead cable. Mast-arm and cable suspension involve considerable lateral strain. Cable suspension may interfere with fire fighting and requires overhead maintenance equipment. Both of these types involve difficulties in cleaning and maintenance, besides placing the signals too high for best visibility to waiting traffic and to operators of vehicles close to the intersection. Suspended signals are desirable, however, at locations where side-mounted signals are apt to be overlooked, as at isolated rural intersections; where high-speed routes enter built-up areas; or where advertising signs and other distracting lights interfere with visibility of signals mounted along the roadway. To improve the effectiveness of the signal indications to waiting vehicles and pedestrians, post-mounted signals may be used to supplement overhead installations at such locations. Signals on posts or pedestals on islands are justifiable only in certain large, channelized, or irregular intersections. Under these conditions, the signals should be well protected by properly designed islands and signs and by night illumination. Any mounting should be substantially constructed, with a strong foundation, preferably eonnete, and should be able to withstand all weather conditions. Installation of Underground Conduit or Cable Underground conduit or cable, though considerably more expensive than overhead wiring, is generally preferable, especially for urban intersections. In certain zones it may be legally required. Before the underground wiring is installed, governmental units and utilities that may have underground structures or facilities at the location or may later place them there should be consulted. Much trouble and possible damages may thus be avoided. Furthermore, 143 sueh organizations can glVe valuable advice as to how such work should best be done. A large proportion of the eost of underground installations Cun b ' avoided if traffic c eon- Hidered in proportioning intervals. r sually the volume of traffic per lane entering the intersection on a Go inteJ'\'al will not be equal from the t\H) directions on tl)(' samc street. The per-lane volume of traffic entering from the IH'avier diredion, therefore, should generally determine the time required for the interval. Unexpected Conflicts During Go Interval :\0 movement which may involve an unexpeeted erossing of pathways of moving traffic should be permitted during any Go interval, pxcept under unusual conditions, when: I. The mO\'ement invoh'eH only slight hazard; 2. HeriouH traffic delayH are materially reduced by permitting the conflicting movement; and :3. Traffic Huhjected to the unexpected conflict is effecti\'ely \\'arncd thereof. When such c(mditionH of possible unexpeeted conflict exist, \Yarning may be given by an illuminated Hign or, under certain conditions, by the use of a flashing signal instead of a green Go Hignal. The foregoing applieH to ,'ehiele-pedeHtrian ccmflietH as well as to vehiclevehicle ('onfl iet s. Vehicle-Clearance Interval A yellO\\' \'(~hieIe-e1earanee interval shall be used following each green interval. In no case shall a yellow interval be diHplayed in conjunction with the change from red to green. 148 In general, the vehicle-(Iearanee interval should be not less than 3 seconds, nor more than i,., reasonably ne('es,.,ary to clear the intersection of traffic. At inters(~etion,., \yherp approaeh speeds are 3{i miles per hour or more the elpararH'p internd on the_ ,.,treet or street,., ha\ing this approach ,.,peed ,.,hould u,.,ually hp at least D seconds. - While elearance interval,., longer than ti ,.,econd,., may occasionally be neee,.,sary at very \yide intpr,.,('(:tions or under other unusual conditions, they are apt to eause impatience among drivers awaiting the signal change and consequent starting before the green indication appears. Theoretically, the display of yellow after red ha,., the effect of advising the waiting motorist to prepare to start. In practice, it has frequently induced waiting drivers to start forward in advance of the green indication. The usc of the yellow elearance interval as a period during which pede,.,trian,., are ,.,upposed to walk is disapproved. The function,., of the yellow interval should be exelusively those of warning approa<:hing driw'r,., and clearing the intersection. Some authoritie,., feel th~tt a short all-\YaY re<1 interval of about 3 second,.,' duration immediately after the normal yellow clearanee interval has merit at ,.,ome intersections in that it provides a brief additional ckaranee p8riod "'hich permits the slower moving pedestrian to eomplete his crossing 'Yithout vehide interference. Adequacy of Maintenance :VIuch of the authority and re,.,pect that traffic ,.,ignals have may be traced to their elear-eut eompelling indications. Signals with impaired efficiency eannot be expeeted to eommand the neeessary degree of respeet. Proper maintenanee i,." therefore, of primary importanee from thi,., funetional vie,vpoint, and ,vill pay other dividends in inerea,.,ing the effeetive life of the signal equipment. :VIaintenanee should he an important eonsideration in the design and pllrehase of traffie signal equipmpnt. If low first eost is follO\Yed hy high maintenance eo,.,ts or by ,.,eriou,., los,.,es of efficiency, it i,., obviously poor eeonomy. The ,.,tandards ,.,et forth herein are intended to pnn'ide the essential feature,., for an adequate maintenanee program. Signal Lamp Replacement Burned-out signal lamps convert traffie ,.,ignab to the role of a traffic hazard. Immediate replacement of ,.,neh lamps, or scheduled replaeement of lamps short of their antieipated lifp, is an extremely important maintenanee funetion. Hemotene,.,,., of signab from maintenance faeilities entail,., delay in replacement of bllrnpd-ollt lamp,.,. In maintenance jllrisdietions where 149 this condition exists, a regular lamp replacement schedule is advised Such a schedule should provide for replacements slightly short of th' life expectancy as determined from consideration of the folIowin; factors: ,~ 1. Theory of probabilities of lamp failure as applied to mass production and manufacturers' rating. 2. The effect of differences between socket and rated voltage. 3. Failure due to vibration and handling. Actual hours of illumination for lamps vary according to lens posi. tion and timing schedules. For example, main-street green and side-. street red will require replacement more often than side-street green and main-street red. These latter in turn will require replacement more often than the yellow. Cleaning The reduction in brilliancy of a signal indication resulting from even a moderate amount of dust and dirt is generally very much underestimated. Signal lenses, reflectors, and lamps should be thoroughly cleaned at least once every 6 months. Lenses and reflectors should always be cleaned when lamps are replaced, unless the last regular cleaning has been very recent. The frequency with which cleaning is required will vary according to the location of the signal. A signal located on a bridge over railroad tracks may require cleaning once a month. Maintenance of Controllers Every controller shall be kept in effective operation in strict accordance with its predetermined timing schedule. Lubrication.-Controllers shall be carefully lubricated, in accordance with a lubrication chart furnished by the manufacturer, at least as frequently as is specified by the manufacturer and more frequently if experience proves it necessary. Different controllers often require lubrication at widely different intervals. Timing.-A careful check of the correctness of timed operation of the controller shall be made frequently enough to insure its operating in accordance with the planned timing schedule. The checking as to timing can be done effectively in connection with cleaning, lubrication, or overhauling. The length of each interval should be recorded for at least two complete cycles. These should then be checked against the timing sehedule, a copy of which should be posted in the control box housing. The necessity for checking timing arises from the possibility of mechanical or electrical misadjustments or unauthorized changes in timing. 150 Painting Signal heads, brackets, poles, posts, control boxes, housings, and conduits above ground should be repainted at least every 2 years, and as much oftener as may be necessary to prevent corrosion and to maintain the good appearance of the equipment. The frequency with which repainting is needed will vary with the paint, the condition of the surface to which it is applied, chemicals in the atmosphere, and other conditions. Maintenance Records Detailed maintenance records should be kept and analyzed at regular intervals to determine future policies as to equipment purchases and the maintenance program. Good maintenance records are valuable in a number of ways: 1. Careful analysis will assist in determining whether or not the maintenance program in use is satisfactory. 2. Analysis of costs will aid in deciding upon types of equipment to be purchased and improvements in maintenance methods. 3. Maintenance records will frequently be needed by the courts in connection with accident cases. Maintenance records should indicate the necessary time required and costs of cleaning, lubrication, retiming, overhauling, lamp replacement, painting, and similar items, for each signal installation and for each specific controller. 151 C-COMPARISON OF FIXED-TIME AND TRAFFIC. ACTUATED CONTROL Relative Adaptability to Normal Intersection Requirements Each of the two 'principal types of traffic 8ignal control, fixed-time and traffic-actuated, posseS8es certain advantage8 not afforded by the other. The choice of equipment should be made only after a review of the relative merits and adaptability of the two types to the particular requirement8 at the location prop08ed for 8ignalization. While fixed_ time control has had by far the wider application up to the present and will very likely continue a8 the more popular choice for reasons which will be discus8ed later, the use of traffic-aetuated control for certain 8ituations is increasing. The following discussion i8 intended to bring out the basic difIerence8 in the two types of control. in80far as their operating characteristicI' and suitability for variou;,; traffic requirements are concerned. With fixed-time control, a consistent and regularly repeated sequence of signal indications is given to traffic. The total cycle length, or time required for one complete sequence of signal indications, is a feature of fixed-time control which can usually be adjusted from a minimum of 30 seconds to a maximum of about 120 second8. A cycle length is selected, based on the traffic demand, and divided into the intervals necessary for handling that traffic. Signal indications then appear in accordance with the predetermined sequence unless changed to other timing schedules by automatic or manual means. This regularity of timing is both an advantage and a handicap. It permits maintenance of an e8tablished time relation with other signals in the area so that vehicles can move through the signalized intersections with a minimum of delay. It does not, however, recognize the short-time variations in traffic flow. In most cases, this means excess or wasted time when cars on one street are required to wait for a signal change although there is no traffic using the other street. The;,;e time losse;,; are small but when they occur frequently may cau;,;e considerable delay, inconvenience, and reduction in intersection capacity. With the traffic-actuated type of control, the cycle length is not predetermined or fixed at any definite value. Similarly, the intervals are usually self-adjusting within certain limits so that they more accurately fit the need8 of traffic. The sequence of intervals normally remains the same, but the time for a complete rotation or sequence of intervals will vary widely. This type of control has a considerable measure of flexibility and some of the time and capacity los;,;es inherent in fixed-time control are automatically avoided. This is especially true at intersections where the traffic load shifts from one street to the other during the period of signal operation. Because of the flexibility characteristics of traffic-actuated control, its principal appli- 152 cation has been at locations not inten:onnected with other signalized interseetions for progressive traffic movement. Many operating yariations arc possible with traffic-ad uated ('ontro!. Interseetion" may have semi-traffic-actuated or full trafficaetuated control. In the former case, the right-of-way or green "ignal is normally giyen to the major street unless a side-street actuation is recei\"ed, at ,,,hich time the right-of-way ,,,ill be temporarily assigned to the side street. This type of control equipment has its principal app!ieation at isolated signal locations ,,,here traffic on the <~ whence TA = 24 seconch 50-1'.4. 250 X 5 From (2), TB = 50~24 = 26 seconds. It should be empha"ized that "uch caleulation" provide only an approximate means of determining the proper time for each "treet. Other considerations, "l1ch a" the time required for pedestrian cro"sing" and physical conditions at the intersection, also affeet signal timing. After the initial selection of a cyele length and a timing program, frequent checkbacks and "tudies of the signal in operation "hould be made to obtain the mo"t efficient timing schedule. A" a general principle of traffic "ignal timing, no n~hicle Go intelTal "hould be les" than the time reCjllired for the \nliting group of pedestrian" to get "tart cd and to crm.;s to a point of safety unless an exChl"i\"e pede"trian internl1 is also employed. Experiment" with sig- 168 1 timing have shmvn that, insofar as vehide movements are eon- narned, exeellcnt efficiem~y can be attained under certain off-peak ~~nditions \yith Go intervals as short as 1:) seeonds. ()r~linarily,.how- e,'er, they .must b~ somewhat longer to gIve the pedestnan a safe oportunity for crossmg the road\vay. P When thel pet e' stnan eross. mg.tIme nms COlH'\lITent1y W'lthtlle "ehide Go period, which is the usual case, the total (;0 interval should be long enough to allmy not less than ;) seconds during which it is indicated that pl'destrians may start to (TOSS, and enough longer to permit pedestrian"! who have entered the roadmly to reach a place of safety with the additional time provided hy the vehieular clearance interval. Thus if it takes 14 seconds for most pedestrians to crm3S the roadway or reach a point of safety, and if the yehicle clearance (yellow) interval is :3' seeonds, the total Go (green) interval should be at least :5 + 14 - 3, or Hi seeonds. Coordination of Fixed-Time Signals In general, all fixed-time signals within 1,200 feet of one another and controlling the same traffic should be operated in coordination. Eyen at greater distances coordination may be desirahle under certain conditions. Great inconvenience and delay result from independent, noninterrelated operation of dosely adjacent signal installations operating on fixed-time control. 1\lost of this delay can he eliminated by carefully planned eoordination. However, under eertain a(}Yerse conditions which seriously affeet the efficiency of coordinated control, greater effieieney may he possible with traffic-aetuated eontrol, operated either independently or in eombination \yith coordinated control. Types and Selection of Coordination The most useful classification of traffic eontrol signal systems is based on their method of eoordination. Since the primary purpose of this coordination is to organize and faeilitate traffic flow, it is essential to understand what yehicular traffic will do under the various systems. On this basis of elassification there are four general types of coordination of fixed-time signals. These are defined as simultaneous system, alternate system, progressiYe system, and flexible progressive system. Simultaneous System In a simultaneous systClm all signals show the same indication to the same highway at the same time. This is one of the early types of signal systems and it has a yery limited applieation in modern traffic signal practice. 169 In its simplest form it involves the use of one controller for a series of signals. At all intersections the timing is precisely the same and indications change simu!taneously to show green at each signal fac_ ing main street traffic aria red to all side streets, and similarly through_ out the cycle. A basically simultaneous system may be made more efficient by utilizing independent controllers at critical intersections to permit some adjustment in interval timing in accordance with local intersection requirements. Intersections less than 300 feet apart often constitute a serious coordination problem. At normal traffic speeds the time required to move from one intersection to the next is so short that a very short cycle would be required for a flexible progressive or alternate system of control. If only two such intersections are to be coordinated, the best plan is generally to operate them as a simultaneous system, giving an ample Go interval on the main street for a major portion of the traffic to clear through both intersections. If two such close intersections are encountered in a larger ;roup to be coordinated, the best plan is to select the flexible progressive system and to adjust the offsets at the two closely adjacent intersections so as to interfere the least with the continuous movement of traffic. Frequently this will result in virtually simultaneous operation of these two signal installations. Except for this limited application and perhaps other occasional exceptions, the use of the simultaneous system is not recommended. In most applications the simultaneous system has serious operating disadvantages: 1. The simultaneous stopping of all traffic along the highway prevents continuous movement of vehicles and tends to result in high speed between stops, but low over-all speed. 2. Cycle length and interval proportioning are usually controlled by the requirements of one or two major intersections in tha system. This often creates serious inefficiencies at the remaining intersections. 3. On streets carrying numerous streetcars, there is an extremely heavy power drain at the beginning of the Go interval. 4. When the main street is completely filled with a continuous line of traffic and this traffic is stopped on a red indication, vehicles from the side street often have difficulty in turning onto or in crossing the main street. Alternate System In the alternate system all signals change their indications at the same time, but adjacent signals or groups of signals show opposite indications alternately along a given highway. The alternate system is usually an improvement over the simultaneous system in that throughout a series of intersections so controlled there can be, under favorablc 170 conditiom" continuous movement of groups of \'ehieles at a predetermined Rpeed, thiR heing completely achieved only where the lengthR of the blocks, or of the alternating groups of blocks, are equal. The inflexibility of the alternate RyRtem lies in the fact that the main street cannot at any interRedion have more than half the cyele for 1),- Go interval without a cOlTeRponding loss of time for the Go intelTal at an adjacent intersection, Hence, for maximum efficiency of through movement the cyele must be divided into equal Go and Stop intervals, Under this condition the side streets all receive aR much Go time as the main Rtreet, \vhich iR ordinarily not conRistent with the relative requirements of traffic on the main and Ride Rtreets, The alternate system can be operated ,,'ith a Ringle controller, but this arrangement is not recommended, Although the alternate "ystem can be used on a, street where blocks arc of equal length to control speeding and to provide equal facility of movement in either direction through the Rystem, it doeR haw limited application for the following reasonR: I, It requires wbstantially equal Go intervals for both mainand side-Rtreet traffic, which iR likely to be inefficient at mORt of the intersections. :2. It iR not well adapted to a Rtreet having hlock,., of unequal length, :~, If the signals arc alternated by groupR the capacity of the roadway is materially reduced during heavy traffic since the latter part of the vehicle group will be stopped by the second signal in the group (aRsuming they are being operated in pairR! when the signal indication changeR, 1. AdjuRtments f01' changing traffic' conditionR are difficult to make. Simple Progressive System In the simple progreRRive Ry"tcm, a common ('yele length is used at each interRection and Go indications arc given independently in ac('ordance with a timing :ochedule deRigned to permit continuouR 01' nearly eontinuous movement of groupR of vehideR along the highway at a planned rate of speed, Synchronous-motor-driven controllers operated by a eommon or pleetri('ally synchronized source may he employed without interconnection in the progressive system and thiR will serve RatiRfactorily until some difficulty caUReR one or more of the eontrollerR to get out of Rtep, The proper time relation between Rignal indicationR at the various loeations in the system must then he re-eRtahliRhed hy adjuRting, with the aid of a RtOP \vakh, the offRetR of those timers ,,'hich are out of Rtpp. 171 If a master controller is used and connected to a circuit which runs to all signal controllers in the system, there can be a constant super~ vision of the time relation between successive signal indications, and timers can be requ4;ed to keep in step. Flashing signal operation can be obtained at any or all intersections, either by local time switch if noninterconnected or from the master controller if interconnected. The simple progressive system is normally far more efficient than either the simultaneous or the alternate system but does not provide the full flexibility possible in a completely modern traffic signal system. Flexible Progressive System The flexible progressive system incorporates all the advantages of the simple progressive system and has a number of additional advantages. A common cycle length is used throughout, but Go intervals are scheduled independently to meet to the extent possible the demands of traffic for movement through the system as well as at individual intersections. Through the use of modern two- and three-dial equipment, timing adjustments to meet efficiently the widely varying needs of traffic at individual intersections and throughout the system are possible. Predetermined timing programs can be set up on the multi-dial controllers to favor rush-hour movements at appropriate periods during the day or week, midday or off-peak traffic demands, and other conditions requiring special timing schedules and cOOI'dination. Such refinements offer great advantages over the unchanging timing plans of earlier progressive signal systems. Careful measure of the demands of traffic and of the potential value of the flexibility features in the multi-dial systems should be made before acquiring control equipment for use in flexible progressive systems. True flexibility is obtained by the interconnection of all controllers in the system with a master controller to permit not only the supervisory check of the coordination between signals but one or more of the following additional features: 1. Remote control of changes in offset relation between controllers to favor movement in one direction at certain times, such as for inbound and outbound peaks. 2. Remote control of changes in total time cycle or in interval timing, or both, to meet the varying requirements of traffic at various periods of the day. 3. Flashing signal operation at any or all intersections. In general, a properly designed and operated flexible progressive system is the fixed-time system best adapted to the efficient movement of traffic. Its advantages include the following: 1. Continuous mOvement of entire groups of vehicles is possible with a minimum of delay and at an average speed planned for 172 the system. This advantage can be realized on both the main and side streets. 2. A high degree of efficiency can be obtained by proportioning the intervals to fit the traffic requirements at each intersection. 3. Speeding is discouraged because a vehicle must make-frequent stops if it exceeds the speed for which the system is planned. 4. Differences in block lengths can be handled better than with other fixed-time systems. Conditions Affecting Efficiency of Signal Systems Certain conditions seriously reduce the efficiency of signal systems, even of the best flexible progressive systems. Among these are: 1. Very short street blocks (assuming signals at all intersections) especially where reasonably high speeds are possible (this particular condition does not affect the simultaneous system). 2. Narrow streets, where parking and loading interfere with free movement. 3. Traffic composed of units of widely differing speeds, such as streetcars, busses, trucks, and passenger automobiles, especiallyon narrow streets. 4. Certain types of complicated intersections, such as those requiring three or more Go intervals per cycle. 5. Heavy volumes of vehicles turning from or into the artery, especially if the block into which they turn is short or otherwise limited in capacity. Nevertheless, some type of flexible progressive system generally gives the best results possible by fixed-time control under such street and traffic handicaps as cannot be removed or relieved. When conditions along a given highway where it is desired to install a signal system are not particularly favorable to fixed-time flexible progressive control, consideration should be given to the possibilities offered by progressive traffic-actuated control or independent trafficactuated control. Manual Control At heavily traveled intersections operating under isolated control, manual operation of signals at certain times may be warranted by varying traffic requirements. The provision of apparatus to permit manual operation of signal installations in a flexible progressive system, however, is not generally rBcommended. Experience has shown that if manual control features are available a tendency on the part of the police to operate certain intersections manually is apt to develop. This often destroys coordination at those intersections and through the system, with disadvantages generally more important than the possible improvement achieved by propor- 173 :r tioning intervals manually. The presumption :,;hould be strongl against ~anual control in coor~inat~d systems Ilnt~l the inability automatIc control to meet the sItuatIOn at the partleular intersection is proved. Speeds for Progressive Systems The speed or speeds for which a flexible progres:,;ive :,;y:,;tem i:,; designed should accord reasonably with what speed studie:,; show would be the speed of vel;1icle movement if cross-traffic delays were eliminated. After drivers have become accustomed to a progressive system, it may be possible to increase the :,;peed with safety. High speeds should be avoided, especially in bu:,;y urhan districts. Except in business districts, progressive systems along arteries are generally timed for speeds ranging from 20 to 30 miles per hour. In general, the more heavily used the artery, the narrower the roadway, the more built-up and busy the district, the shorter the blocks controlled, the more mixed the types of traffic, or the more pedestrians and cross-street traffic there are, the slower should be the design speeds. Local authorities should be careful to avoid design speeds that will conflict with Stats laws governing speeds. Signs Indicating Timed Speed Traffic Signal Speed signs should be erected to guide drivers operat- ing under an a1t2rnate, simple progres:,;ive, or flexible progressive system. Where the system timing is different for various periods of the day, however, the resulting speeds may vary enough to make this posting of speed signs impractical. When such signs are used, they should be mounted on, or as near as pos:,;ible to, each :,;ignal where the timed speed changes, and at intervals of not more than two blocks throughout the system. Coordination With Railroad Crossing Signals Traffic :,;ignals near railroad crossings shall be interconnected with the flashing light or wigwag signals or gates at the railroad grade crossing and with all other traffic signals on the same street or intersecting street within 500 to 1,000 feet of the crossing to the extent necessary to prevent conflicts between rail and highway traffi(. The signals shall be so operated as to prohibit, to the maximum extent practicable, vehicles from entering the roadway bstween the railroad cl'Ossing and the intersection near the crossing as trains appl'Oach and travel thl'Ough the crossing area. On the approach of a train, all signals which could permit vehicles to reach the crossing area without having another red indication before them shall, unless already showing red, go immediately to yellow and then to red. remaining red until the crossing is clear. At all other 174 times, these signals should operate as standard flashing signals or a" Stop-and-Go signals, depPDding on the conditions \yarranting their installation. Rate of Flashing When fixed-time signals are put on flashing operation, the rate of flashing shall he not less than 50 nor more than GO times per minute. The illuminated period of each flash shall be approximately equal to the nonilluminated period. 17,5 E-TRAFFIC-ACTUATED SIGNALS Definition '~ A traffic-actuated signal is a type of traffic control signal in which the intervals are varied in accordance with the demands of traffic as re!!;istered by the actuation of detectors or push buttons. ]. A semi-traffic-aetuated signal is a type of signal in which means are provided for traffic actuation on only some of the approaches to the interseetion. 2. A full traffic-aetuated signal is a type of signal in which means are provided for traffie actuation on all approaehes to the interseetion. 3. A speed control signal is a type of si!!;nal in whieh means are provided for traffic actuation on some or all approaches and which provides Go indications in sueh a manner that vehicle speeds on one street are limited to a preselected maximum value. Warrants for Intersection Control Because traffic-actuated signals at intersections do not normally delay traffic exeept when it needs to be delayed to avoid conflict with traffic on cross streets, it is not advisable to set values of minimum traffic volumes or other fixed warrants for their installation. There are, however, a number of factors that should be eonsidered and weighed before selecting and installing such signals. These factors are: ]. Vehicular volumes.-At intersections where the volume of vehicular traffic is not great enough to justify fixed-time signalization, traffic-actuated signals may be applied if other conditions are such as to indicate the need for Stop-and-Go signal control and if the cost of the installation can be justified by the conditions. 2. Cross traffic.-When the volume of traffic on a main street is so great as to restrict and jeopardize unduly the movement of vehicular cross traffic on a minor street, semi-traffic-actuated signals may be installed to provide assignment of right-of-\Yay to the cross street without seriously delaying traffic on the main street. Traffic-actuated signals are desirable at all s\lch signalized intersections, except in cases when they constitute a part of a coordinated or progressive system, thus warranting fixed-time control. 3. Peak-hour volumes.-When signal control is required at an intersection during only a small part of the day, such as during peak traffic hours, traffic-aetuated signals may be installed 176 if economically justified, SUlce they will not unduly delay traffic at other times. .~. Pedestrians.-If the principal need for a traffic signal is to accommodate pedestrian traffic, traffic-actuated signals are usually desirable and may be economically justified. _ Most urban intersections with heavy pedestrian volumes also have heavy vehicular volumes and thereby warrant the usc of fixedtime signals. However, signals may be warranted at special locations, such as in the vicinity of schools, when pedestrian crossings are the primary consideration. In these special cases, traffic-actuated signals will delay vehicular movements only when the streets are in use by pedestrians. D. Accident hazard.-When a study of intersection conditions indicates that signalized control would be an effective remedy for the acddent hazard existing, but the minimum warrants established for installation of fixed-time signals are not met, a traffic-actuated signal installation may be justified. 6. Wide traffic fluctuations between streets.-When the preponderance in traffic varies from one street to another, at an intersection where one or more of the warrants for fixed-time signals is substantially fulfilled, full traffic-actuated control will usually provide the greatest efficiency in intersection operation. 7. Complicated intcrsections.-Traffic-actuated signals offer special advantages at complicated intersections with conditions substantially warranting signals, where multiple traffic phases are needed, in that they are capable of skipping phases when some of the streets are not being used. In each case, they use only the time aetually then required, thus providinll; a high degree of efficiency. 8. Unwarranted signals.-When traffic authorities are compelled to install traffic sill;nals at locations where they are needed for safe and efficient movement, traffic-actuated types should be employed. They cause a minimum of unnecessary delay and thus do not tend to break down public respect for traffic signal control. .9. Progressive signal s,ljstems.-When the spacing or character of some intersections in a fixed-time progressive signal system is such that satisfactory progressive timing cannot be achieved, traffic-actuated control may be employed at those intersections. 10. Speed control.-If approach speeds present a particular hazard at intersections, in addition to normal intersection problems, full-actuated control employing speed control on the artery may be installed for best results. 177 Warrants for Nonintersection Control Special conditions at roadway locations other than intersections may warrant the installation of vaffic-actuated signals. Some of the factors that may justify such installations are: 1. Speed control.-Traffic-actuated signals may be used to Control speeds at the approaches to special roadway locations such as bridges, sharp curves, and entrances to towns. The; may be of especial value at school zones if speeds average higher than 35 miles per hour in rural or 25 miles per hour in urban areas. 2. One-way restricted zones.-At locations on two-way roadways where traffic can only move in one direction at a time, such as at narrow bridges and tunnels, traffic-actuated signals may be applied to assign the right-of-way and to provide clearance intervals in accord with traffic requirements. 3. M idblock pedestrian protection.-Pedestrian crossings concentrated at schools where intersections are a considerable distance apart, and at other midblock points, often justify use of pedestrian-actuated signals. The installation of signals between intersections for the purposes indicated above should be accompanied by the erection of appropriate 8igns advising the motorist of this special application. Immediately 8ub8equent to installation, there should be a period of strict enforcement so that disrespect for signal indication8 will not develop. Types of Traffic-Actuated Control, and Factors Governing Selection As indicated earlier, traffic-actuated signal control" may be classified in two general categories: (1) Semi-traffic-actuated, and (2) full traffic-actuated. There are also several special types of applications for traffic-actuated equipment. The8e include: (1) coordinated control, (2) pedestrian-actuated control, (3) speed control, and (4) oneway restricted zone control. All these special applications make it essential that a thorough knowledge of the traffic and physical facts be obtained prior to selecting equipment for installation. To aid those who have the problem of choosing the proper type of equipment for a particular job, the characteristics of the two general types of traffic-actuated control and the several special applications are presented below. Semi-Traffic-Actuated Control Semi-traffic-actuated control is applicable primarily to intersections of a heavy-volume or high-speed traffic artery with a relatively lightly traveled minor street. Detectors are located only on the minor street. The signal is normally green on the artery, changing to the minor street only as a result of vehicle or pedestrian actuation. In some 178 types of controls the minor street green interval is of fixed duration, but in the more flexible types the duration of the minor street green interval is proportioned to the traffic demand thereon, with provision for a maximum limit beyond which the green light may not be retained on the minor street even when traffic demands thereon is heavy. IIpon the expiration of the required, or maximum, minor street interval, the Go signal will revert automatically to the artery where it must remain for at least a predetermined minimum interval. At the expiration of this minimum interval the control is again free to respond at once to minor street actuation. Full Traffic-Actuated Control Since semi- or part traffic-actuated control does not measure the demands of certain traffic streams, it cannot attain the efficiency of full traffie actuation. Therefore, full traffic-actuated control should be selected for intersections where failure to take into account certain traffie demands will seriously affect the efficiency of control. In full traffic-aetuated control, deteetors are installed on all approaches to the intersection and right-of-way is assigned to a street only as a result of actuation thereon. When there is no traffie on either street, the green indication will ordinarily remain upon the street to which it was hst assigned. The duration of the green interval on any street is dependent upon the traffic demand on that street, subject to a maximum time limit in the event of a continued demand and the presence of traffic on the other street. In the event of eontinued actuation, transfer of right-of-way will be made to waiting eross traffic after a predetermined maximum period, and in this ease, right-of-way will automatically be returned to the first street at the earliest opportunity without the necessity of further actuation. Full traffic-aetuated control can be applied to more than two-phase operations. Equipment is available for three- and four-phase intersections. Operation of eontrollers at such interseetions is similar in principle to operation at two-phase intersections. Opportunity for the right-of-way is accorded to the several phases in rotation and phases for which there is no traffic demand are skipped. In three- or four-phase eontrols, provision ean be made for allowing additional noninterfering traffic flows to move during more than one phase. Thus, a three-phase eontrol may handle four or five flows. provided only three of them are eommonly interfering. A recently developed form of full traffic-actuated controller operates upon a "VOlume-density" basis, many of its circuits being subjeet to automatic and continuous adjustment with respect to variations in volume, relative densities on the two opposing traffic phases, elapsed time between actuation and assignment of right-of-way, and other factors. As this form of control is essentially "platoon respon- 17B sive," it is capable of facilitating progressive platoon movements. This is discussed in the following section on coordinated control. Coordinated Control There are three principal applications of traffic-actuated equipment in coordinated operation of a series of related signalized intersections. These are characterized by the features described in the following paragraphs: Supervisory background cycle.-In one type, a supervisory background cycle is imposed upon a series of semi-traffic-actuated controls. this being accomplished by a master timer sending out impulses over interconnecting wires to each semi-actuated controller, or by local syn('hronous motor control at each intersection. The l:ackground cyele is set up in the same manner as for fixed-time ('ontrol, a time-space chart being worked out for the series of intersections that will give the maximum travel band through the area. The fmwtion of the supervisory cyele is to assure that the local semiactuated controllers provide at least the minimum of Go time, and in the time relation called for in the time-space chart. In addition to this minimum Go time, each semi-actuated controller adds to its artery Go interval all time not required by traffic-actuated demand on the minor street, thereby providing the widest possible travel band. One possible disadvantage is that such an extended Go interval may seriously overload a subsequent intersection at which cross-traffi(' requirements are greater. It is also apparent that the above type of operation does not provide the speed control characteristics of a fixed-time progressive system, and hence should be used only where the consideration of moving maximum amounts of traffic with the least delay outweighs thc desirability of speed limitations. V olvme density control.-Another form of coordinated traffic-actuated ('(mtrol is accomplished by the use of full-actuated controllers of the so-called volume-density type. This type of control operates so that no background cyele or interconnection is used. The controller is capable of responding to the natural platoon movement of traffic. The impulses from an advancing platoon of cars are received by the controller and tend to produce a foreing effeet in seetHing a Go interval for the\group of vehieles, this tendency being increased by a carryover effect impressed upon the control mechanism by the passage of the previous platoon. Increased spacing of vehicles at the end of the platoon is sensed by the eontroller and utilized to terminate the movement. It is thus possible for platoon movements to affect a series of traffic-actuated intersections of this type in such a way as to set up a pattern of progressive movement based on natural speeds and Rpacmgs. 180 Special use in a flexible progressive system.-A further application of traffic actuation in the field of coordinated movement occurs in a fixed-time flexible progressive system where intersection spacing at one or more points in the system may be such that the best possible progressive timing arrangement involves considerable ~eduction or displacement in the progressive Go band. Multiple intersections in a progressive system may also cause difficulties in the time-space chart. In these instances, full traffic-actuated control may sometimes be effectively employed to bridge the gap. Pedestrian-Actuated Control Operation of both the semi- and full traffic-actuated controls, as well as certain types of fixed-time controls, can be accomplished by pedestrian push buttons. Such actuation may affect movements in any of the following ways: 1. Pedestrian actuations are handled on the same basis as vehicle actuations. No special signal indications are shown for pedestrians. 2. Pedestrian indications (WALK, WAIT, or equivalent) are shown in parallel with the vehicle indications. The most desirable types of such controls provide for a termination of the Walk indication sufficiently in advance of the expiration of the vehicle interval to permit persons who have left the curb to complete the crossing of the street without vehicular interference. 3. An exclusive pedestrian interval, normally justified only under conditions of low vehicle volume at high speeds and heavy pedestrian movement, is inserted in the signal cycle and during this interval all vehicle traffic is stopped. 4. In the case of pedestrian-actuated signals that normally operate in conjunction with fixed-time intersection signals and which have the pedestrian interval introduced into the cycle upon actuation of the push button, the pedestrian interval can either be taken from one of the vehicular traffic greenlight periods or be added to the cycle without decreasing either of the green periods. During flashing operation of signals at night, actuation of the push button changes the flashing signals to give a steady red Stop indication to the major traffic flow crossed by pedestrians, with or without a special Walk signal. Equipment is also available for the protection of pedestrian cross walks at midblock locations, schools, and similar locations. With this form of control the green signal shows normally to traffic on the thoroughfare, right-of-way being accorded to the cross walk upon push-button actuation. After providing an interval for pedestrian 181 movement, these signals automatically return the right-of-way to Ve- hicular traffic, and give a predetermined and adjustable minimum in- terval to this traffic before the pedestrian indication can again be obtained. ';I" Speed Control Speed control can be applied at nonintersection locations and abo at full traffic-actuated controlled intersections. N oninlersection speed control.~An adaptation of the traffic-actuation principle affords a means of controlling the speeds of vehides at nonintersection locations such as curves, bridges, and school zones. The component parts of the system are a speed controller, a vehicle detector, and a traffic signal. The signal indication is normaJly red or Stop. Detector actuation at a point in advance of the signal initiates the timing of a delay interval after which the signal is changed to a green or Go indication in time to permit the passage of a vehicle traveling at or below the maximum allowable speed (i. e., covering the distance between detector and signal in not less than the timed in terval). A vehicle traveling at too great a speed will arrive at the Stop line before the signal changes from Stop to Go and hence will be required to stop. Succeeding vehicles, if closely enough spaced, will extend the Go indication, but when the maximum spacing is exceeded the red indication is at once shown and speed control again becomes effective. This type of control should always be identified with appropriate signs so that the motorist will recognize and understand the function of the signal. For the same reason, some additional enforcement may also be desirable for a period immediately after the installation is made. Intersection speed conlrol.~At interseetion locations where speeds OIl the artery approach present a particular hazard in addition to til(' normal problems of intersection control, it may be desirable to employ full traffic-actuated control incorporating speed-control featllJ'('~ on the artery. All signals normally show red in the absence of approaching traffic. A single vehicle approaching the intersection on the main street and (:rossing the detector will receive the green indication at the end of a vehide approach period. If the vehicle is traveling at or below the' speed designated as safe for the location, the green indieation will come on in time to allow passage through the intersection without delay. If, on the other hand, the approaching vehicle is coming too fast, it will have to slow down or stop before the green indication will be displayed. A ear following close enough so that it crosses the detector before the green indication period for the first car expires will extend the 182 given period, thuH allowing itself time to paSH the intersection. A platoon of ears can all proceed through the intersection, hy this extension feature, without interruption. The speed control inherent in this latter ease lies in the fad that the first ear of the platoon is monitored for speed as it approaches the intersection. Should a hreak _occur in the line of ears long enough so that the speed of the next ear will not be so controlled the signal will have returned to red. This ear upon crossing the detector will institute a new vehiele approaching period and thus monitor its own speed. The vehicles approaching the signal on the main street from one direction and obtaining the green indication do not cause the same indication to be displayed toward the other direction on the main street. Signals facing in the opposite direetion on the main street remain red in order to have a speed-monitoring effect on traffic which may approach from that direction. When the signal is not to tranHfer the right-of-way to the cross street, the main-street indication changes directly from green to red in order to give immediate speed-monitoring effect for other approaching vehicles. This is a satisfactory procedure inasmuch as had the next following ear been close enough to get into trouble it would have heen close enough to extend the green light period. If cross traffic is waiting and traffic is moving through the interHection in one direction on the main street, a driver approaching the signal from the other direction on the main street will not receive a green indication unless there is time for him to go through the interseetion before right-of-way is transferred to the cross street. If there is not sufficient time hefore the right-of-way transfer is made, the green light will be returned to the waiting driver on the main street after the cross-street traffic has passed. On the cross street the display of the red signal is always preeeded by a yellow signal as in normal signal operation. A clearance interval is alwayH provided for the main street when the green signal is to be given to the cross street. If there are ears on the main street between the detector and the intersection that must be stopped a yellow Hignal is displayed to them during this period. Otherwise the elearance period is all red. A maximum period limits the time that moving traffic on either street can maintain its right-of-way against waiting cross traffic. One-Way Restricted Zone Control Full traffic-aetuated control equipment iH available for use at a narrow passage, such as a bridge or tunnel, which is not wide enough to allow traffie to flow in opposite directions simultaneously. This control operates essentially as a full traffic-actuated two-phase control, each approach being one phase. \yith an all-red clearance period added 183 to the normal cycle. Traffic moves in one direction on one phase and in the opposite direction on the other phase. Between these movements the all-red interval provides time for clearance of such traffic as may be in the restricted area. ,'#' Detectors and Controllers Since the traffic-actuated signal, as its name implies, responds to vehicle or pedestrian actuations by providing Go indications for the appropriate movements, it is necessary that detector and controller equipment be designed for this service. In this respect, traffic-actuated signals differ considerably from fixed-time signals, which require no detector units and a somewhat simpler timing mechanism for their control. The design characteristics of the various types of detectors and controls that have been developed for use with traffic-actuated equipment are described below. Types of Detectors A wide variety of detectors can be used with traffic-actuated sIgnals. These are classified as follows: 1. Pressure-sensitive detectors. 2. Magnetic detectors. 3. Sound-sensitive detectors. 4. Light-sensitive detectors. 5. Pedestrian push-button detectors. Some of these offer special advantages for particular physical and traffic conditions, and the type of detector should therefore be selected with care. To aid in this selection, the characteristics of the several types are outlined below. Pressure-Sensitive Detectors Pressure-sensitive vehicle detectors are of two general types. The most common type is actuated when crossed by vehicles traveling in any direction. In the other type, used principally on narrow twoway roadways, actuation occurs only when the detector is contacted by vehicles traveling in one direction. A brief explanation of the two types follows: N ondirectional detectors.-Detectors of the nondirectional type operate on the open-circuit principle, with electrical contact established only at the moment that vehicle wheels pass over the rubber surface. Directional detectors.-With directional type detectors, vehicle impulses are passed into the signal controller from traffic in one dirc('tion only, impulses being rejected from traffic moving in the opposite direction. While similar in appearance to nondirectional detectors, the directional type contains two separate sets of electrical contacts, rather than one. 184 Magnetic Detectors Magnetic detectors are available in two general types: (l) non- compensated, which have a wide zone of influence; and (2) compensated, which have a sharply defined zone of influence. They are not rendered inoperative or continuously operative by parked cani or_ hy other fixed metal objects within their zone of influenee. N oncompensated detectors.-K oneompensated magnetie detectors are mounted in or under the road\yay surface and are usually (~apahle of providing a road coverage up to about 15 feet on either side of the detector. They are not reeommended for use at locations suhject to severe and fluctuating electromagnetic influenees sueh as arc caused by streetcars and trolley busses. Compensated detectors;-Deteetors of the compensated magnetic type involve two magnetic ~iremits and are so designed that their operation is not affected by extraneous electromagnetic influences. They are characterized by a relatively sharp definition of their zone of influence, usually extending only about 6 inches beyond each end of the detector. A further eharacteristic of the best deteetors of this type is that they are capable of a high degree of directional discrimination and can, therefore, be used to detect vehicles by lanes of travel. Sound-Sensitive Detectors Detectors of this type consist of a hollow metal chamber with a steel top plate and are actuated by sound waves set up in the chamber by the passage of a vehicle wheel over the top plate. These detectors are not affected by ordinary external noises not associated \\'ith the passage of wheels over their surface. They are not directional. Light-Sensitive Detectors The passage of a vchide can be detected by the interruption of a beam, or beams, of light between a light source and a photoelectric cell or cells. Sequential interruption of two beams of light can be utilized to provide directional detection. Pedestrian Push-Button Detectors In addition to detectors for registering the demand of vehides ap- proaching an intersection, it is in many instances desirable that means be provided for registering pedestrian traffic demand. Pedestrian push buttons arc used for this purpose and are properly regarded as a form of detector. In order to be suitable for traffic-actuation purposes, a push button must be designed to withstand rigorous service. Types of Controllers Because traffic conditions are subject to wide variation, it is neces- sary that traffic-actuated controllers have sufficient flexibility of op- 185 eration to meet all normal conditions and as many others as possible. Ready adjustments of various time intervals over wide ranges should be possible. ,~ In traffic-actuated controls, Go signal intervals for the approaches with actuation have an initial portion, to permit standing traffic to get into motion, \vhich is followed by one or more unit extensions, the number and duration of which are determined by the traffic itself within the timing limitations pre-set on the controller. A maximu~ period protects waiting cross traffic against undue delay in the event that traffic on the other street is very heavy. Clearanee intervals are provided at the end of the Go interval. In semi-traffic-actuated eontrol, the Go interval is normally accorded to the main street, being called to the cross street upon actuation by cross-street traffic. The cross street has an initial portion, which may be followed by an extension portion if cross-street traffic requires. The main street, not having actuation, has only one predetermined period, namely, the minimum period. At the end of this minimum period the Go indication can again be transferred to the cross street in response to actuation. The main-street minimum period should therefore be set at a value to take care of the expected normal main-street traffic. All these portions, intervals, and periods should be readily adjustable by suitable knobs, pins, or dials which will require the use of no tools. The limits between which they should be adjustable for the various types of eontrol are presented below. The ranges of timing adjustment shown are desirable, but in actual operation the adjustment of Go intervals within the range provided should always be made with a view toward safeguarding pedestrian movements. as well as to facilitate vehicle traffic. Two-Movement, Semi-Traffic-Actuated Controller with Time Extension For this type of control the interval timing should be adjustahle within the following limits: Main-street minimum pcriod_ _ Clearance intervals _ Cross-street initial portion_ Cross-street extension limit- Cross-street maximum period 8eCOlld8 10-90 2-10 2-12 2-12 10-60 Two or More Movements, Full or Semi-Traffic-Actuated Controller with Time Extension The various intervals in two-, three-, or four-phase controls, in 186 phases susceptible to extension by traffic actuation, should he ad- justable between the following limits: Seconds Maximum period . 10-60 Initial portion _ 2-30 Extension limiL __ . 2-30 Clearance intervaL _. 1-10 Phases not having extension by traffic actuation should have minimum green signal intervals adjustable between 10 and 90 seconds on the main streets and between 10 and 60 seconds on minor streets. Traffic-Actuated Speed Control for Nonintersection Locations N onintersectional speed controls such as may be used on a curve or at a school zone, narrow underpass, or other roadway hazard should have intervals adjustable between the following limits: Vehicle approach period Extension limit. . Vehicle indicator period . _ Seconds 1-10 1-10 3-30 Two-Movement, Full or Semi-Traffic-Actuated Controller With Speed Control This is the type of controller used at intersections of two streets where excessive speed on one of the streets is an important factor. The various intervals should be adjustable between the following limits: Maximum period_ Initial portion _ All extension limits_ . All clearance intervals All vehicle approach periods. Seconds 10-60 2-30 1-10 1-10 1-10 Two-Movement, Full Traffic-Actuated Controller With Automatic Adjustments of Periods With Respect to Traffic Volume, Relative Density, and Elapsed Time In this type of control the various intervalH and actuations should he adjustable between the following limits: Minimum initial portion __ seconds_ 5-60 Increase of initial portion per car. __ do _ 0.1-2 N umber of cars before minimum initial por- tion starts to increase __ cars i)-50 Passage period_ . seconds. Minimum time to which extension limit can he reduced. _ do 1-10 1~7 Waiting time to reduce extension limit to mInImUm --_ _ _ seconds_ - - 10-90 N umber of waiting cars to reduce extension limit to minimulJ). . __. ________ ___ ears ;")-40 Density of traffic into green signal (number of cars per 10 seconds to reduce extension limit to minimum) . _ cars ;")-40 Clearance intervaL Maximum period - _. . _ seconds _ do _ 1-10 10-90 Carry-over effecL - - __ ___ - - - - - _ percent _ 10-90 Two-Phase, Full Traffic-Actuated Control for One-Way Restricted Zone With this control the initial portions, extensions, and usual yellow clearanee intervals, as well as the maximum intervals, should be timed in accordance with the usual procedure given heretofore. In addition, the all-red clearance interval, during which traffie that has entered the restricted area during the display of the Go signal is allowed to dear, should be adjustable between the limits of 10 and 70 seconds. Additional Flexibility for Controllers Used in Coordinated Systems Where a series of interseetions along a main street equipped with traffic-actuated control, using aetuation on the cross streets only, are to be coordinated, the equipment may be such that the time at whieh each control can respond to a cross-street actuation is determined by a master timer, or by a local synchronous motor timer. Provision for Manual Operation Manual operation of traffic-actuated signals is not generally reeommended. The wide flexibility of operation they afford is usually adequate to eare for varying traffic demands. However, where traffic conditions are so variable as to make normal operation of the signals inefficient and undesirable at certain times, switches for manual operation of the controller may be provided. Such switehes should not be aceessible to police officers who are not especially trained and experienced in the direction and control of traffic at intersections. When the control is being operated manually, actuation of the manual control push button causes the signals to change their indications to those normally displayed in the next interval. Signal display will then remain unchanged until the manual control push button is again actuated. Installation of Traffic-Actuated Signals The installation of signal heads, controllers, and certain other elements of traffic-actuated signals involves the same considerations as those described in Fixed Time Signal Head Locations, applicable to 188 all signals. Details of the location and installation of vehicle detectors, however, deserve special explanation because of their importance to the efficient and reliable operation of traffic-actuated signal equipment. Distance of Vehicle Detectors From Stop Line The proper location for vehicle detectors in relation to the Stop line depends upon the type and operating characteristics of the controller, the speed of vehicles approaching the intersection, physical characteristics of the roadway (grades, widths, parking, visibility, etc.), and special signal functions (turns on separate intervals, stopping sideroad traffic before entrance to high-speed artery, etc.). With conventional full and semi-traffic-actuated controller equipment used under average conditions-i. e., level roadway, not more than two traffie lanes in each direction, and good visibility-good results have been obtained when the distance from the Stop line to the detector is related to the speed of approaching vehicles as follows: Speed (miles per hour): Less than 20 _ 20-30 _ 30-40 ___ _ _ _ __ 40-.50 __ . _ Over 50 _ Distance from stop line (feet) 110 140 170 210 When the approach to the intersection is on a grade, the distance from the Stop line should be increased about 4 percent for each 1percent down grade and decreased about 4 percent for each I-percent up grade. Where there are more than two lanes approachin?; the interseetion, and visibility is not restricted, it has often been found desirable to increase the above distances by small amounts, since higher speeds through the intersections usually can be allowed with safety. The increased distances in such cases may be as much as ]5 percent ?;reater than the average values given above. Under no eondition should detectors be located less than 40 feet from the Stop line. Where they are installed to permit left-turn movements on a separate si?;nal interval, detectors are usually placed mueh closer to the interseetion than for the control of normal traffic. 'Where a minor road interseets a high-speed route, it may be desirable to foree most ears on the side road to stop before enterin?; or erossin?; the artery. In sueh eases, the spacing of detectors should be shortened on the side street so that most ears will arrive at the Stop line on a red signal. Bus stops, filling-stations' drives, and other special eonditions near an intersection may necessitate the installation of a second deteetor 189 very near the Stop line. Such installations would in no way interfere with the spacing of the initial detectors of the street so affeeted. Speed-control signals nonpally require longer spacings between de- tectors and Stop lines, so that desired speed reductions can be achieved gradually and stops required only in rases of abnormally high speeds, or at intersertions when right-of-way has been assigned to the (TOss street. For normal road\vay and traffir conditions, \vhen speed-rontrol features are provided, the recommended distance from the Stop line to the detertor as related to the speed of approaching vehides is as 1'ollo\vs: Distancc frO/ll stop til/! Speed (miles per hour) : (.feel) 20-30. HlO 30-40. 220 40-50. 2G;j 50-GO :32;) Over GO :350 These values Hhould also be inneased or decreased, as explained previously, to arcord with roadway grades, visibility, and special traffie ronditions. vVhere speed control is applied at an interHection, the above values should be used in locating deteetors on the artery awl those previously given for standing traffic-actuated control should be used in lorating the detectors on the side road. Detectors for \lse with t\vo-movemcnt. full traffic-actuated eOll- trollers with automatic adjustment of periods with respect to traffic volume, relative density, and elapsed time should be located farther from the Stop line than would \w the case with other types of traffic- actuated (ontrol. This enables the control to recognize the presene(' of platoons of ears and in general to get the complete data on traffic' conditions neeessary to regulate its refinements of control. For nor- mal roadway and traffic ronditions, the recommended distance from t he Stop line to the detector ai' related to the speed of approaching \'('hie1es is as fo11O\\'s: INstance frolll stop linc Spepd (mil('s per hO~lr) : (feet) 20-30 240 :30-40 270 40-50 :320 Over 50 :3/;) For special roadway conditions these values may be changed a" recommended for other types of installations discussed above. 'Where t he greatest coordination effeet is desired between a i'erie" of inter- \ \10 I sections, the detector spacings on the street on which through moyement is desired should be increased about 20 percent. Location of Vehicle Detectors From Center Line Pressure-sensitive and sound-sensitive detectors should be placed transversely in the roadway so that all vehicles approaching the intersection cross them with one or more wheels. No vehicle moving away from the intersection should normally cross the detector. When physical conditions are such that more than an occasional car leaving the intersection crosses the detector, a directional detector should be installed so that this traffic will not actuate the controller unnecessarily. The end of the pressure-sensitive detector nearest the center line of the road should usually be placed about 3 feet therefrom. If the approach side of the road requires more than one detector to cover it satisfactorily, the detectors should be spaced so that the end of the rubber surface of one will be 4 feet from the next. This will insure that no car can pass between the detectors without causing an actuation. In the case of pressure-sensitive detectors, consideration must be given to parked vehicles. In areas where curb parking is allowed, detectors should never be located so that a properly parked car can stand with a wheel on the detector. On one-way streets, the entire roadway should be given detector coverage, except as spaces may be necessary from each curb for parking. The compensated type of magnetic detector should be buried in the road with the end nearest the center line approximately 4 feet therefrom. If additional compensated magnetic detectors are required to cover the distance to the curb, they should be spaced so that their ends will be about 4 feet apart. The compensated magnetic detector has a rather sharp cut-off and, in general, a vehicle must pass either over it or within 6 inches of its end to cam,e an actuation. The noncompensated type of magnetic detector does not have as sharp a cut-off as the compensated type. Its zone of influence is not so clearly defined. It should, therefore, be located under the path traveled by the right wheels of a car traveling in the center of the lane to be covered. A noncompensated magnetic detector can usually be adjusted to cover about 25 feet of roadway. In special cases noncompensated magnetic detectors may be located in or on the shoulder of the roadway. Light-sensitive detectors, employing photoelectric cells and light beams across the roadway, are normally used only at special locations such as bridges and tunnels. They must be mounted so as to deteet the approach of vehicles by having the light beam interrupted by the passing cars. The beams may he in either a vertical or horizontal plane, but if mounted in the open, consideration must be given to Hll Hnow and ice conditions if the beam iH uHed in a vertical plane. Parked carH would seriously handicap their use in many places. Installation of Pedestrian Detectors Pedestrian detectors or 'push buttons are available for mountinl!; on either wood or steel poles. They should be conveniently located near each end of eross walkH used by pedestrians at the roadway location controlled by the signal. The detector should be 3Y2 to 4 feet above the sidewalk and in view of persons usinll; the cross walks. Penmmenttype sill;ns should be mounted just above the detectors, explaininl!; their purpose and use. When pedestrian detectors are provided for special purposes, such at; at school crossingH, and are to be used only by authorized persons, lock s\yitches should be installed so that the detectors can be operated only by persons with keys. Such detectors are not intended for the use of the general public and the supplemental signs are not necessary. Installation of Streetcar Detectors \Vhen streetearH operate on streets where traffic-actuated sil!;nal equipment is installed, it is necessary to provide special devices to detect the approach of the streetcars. This distance of detectors from the Stop line is usually determined in the same manner as that for vehide detectors. However, when streetcar stops or other conditions make it necessary, the spacing between the streetcar detectors and the Stop line may be shortened, or a second detector may be provided on each approach to the sill;nal. Operation and Adjustment of Traffic-Actuated Signals ,\s with all types of signals, it is necessary that appropriate ()quip- ment be installed to meet the normal traffic requirements of a givpn roadway location. Assuming the availability of the proper equipment, it is still necessary to adjust and operate the equipment as nearly in accordance with the needs of vehicular and pedestrian traffic as is possible. Continuous Operation Traffic-actuated signals of all types should be operated at all times as Stop-and-Go devices except: 1. As a caution signal (flashing yellow) when interconneeted ,,-ith other signals and/or remotely controlled for emergency vchides such as fire trucks; or 2. As a caution signal, or as a combination caution and Stop signal (flashing yellow on certain approaches and flashing red on others) when failure of controller, wiring, or signal lamps prevents normal operation. 192 ~inee (raffie-actuated signals, properly timed, eause a mllllmum of unneeessary delays, there is no justifieation for changing them to flashing operation during light traffic periods. Right-of-way is normally denied approaching motorists only when intersecting streets are m use by others or when safe approaeh speeds are exeeeded. Time Intervals and Adjustments In order to obtain the greatest efficiency from traffie-aetuated equipment, the correet setting for the various time intervals must be determined. This often requires some trial and experimentation after the installation has been made. The following explanation is intended as a guide for those not thoroughly aequainted with the general prineiples and terminology associated with the operation of traffic-actuated equipment. In general, it will be desirable for a person not familiar with sueh time intervals and adjustments to seeure the advice of an experienced representative of the company that manufactures the equipment or of some other well-informed person, until the desired settings and adjustments are well understood. It should be added that these settings and adjustments sound more eomplicated than they are found to be with experienee. The minimum Go signal interval on a street having traffie-actuated control with time extension includes an initial portion followed by a unit extension. If there is a line of ears crossing the detector after the initial portion has expired, eaeh ear erossing the detector will eaneel the unexpired remainder of the previous unit extension and initiate a new unit extension. Thus ten car8 sueeessively extending the Go period will no( nece8sarily cause the Go signal to remain on that street for ten times as long as one ear would. The Go 8ignal will be transferred to the cross street, if there is waiting traffie thereon. following the expiration of the last unit extension. From the foregoing explanation it ean be seen that the unit extension represents the time spacing between cars approaching the green light in excess of whieh it is desired that the right-of-way be yielded to wai ting eross traffic. Sinee traffie-actuated equipment eontrols permit considerable flexibility in the selection of the Go period, extreme care must be used to safeguard pedestrian movements by provision of a minimum length of Go interval which will accommodate the slower pedestrians. The various settings and adjustments necessary for operation of traffic-actuated eontrols are as follows: Initial portion.-Thc initial portion should be adjusted to a time which, added to a unit extension, will permit a solid line of cars between the detector and the Stop line to rlear the intersection. 193 Unit extension.-The unit extension should be set so that a car which has actuated the detector, if it is traveling at a speed normal for the street, will clear the intersection before losing the right-of-way . .LvIaximum period.-Tbe maximum period is brought into play only when continuous traffic prevails and cross traffic waits. The point to be considered in setting it is that, when traffic becomes very heavy on both streets, the signal operates, in effect, as a fixed-time signal, and the maximum period determines the proportion of time to be allotted to each street. Clearance interval.-The elearance interval is set at a value that will permit moving traffic to come safely to a halt when a Stop signal is displayed. Vehicle approach interval (speed control oj the nonintersectional type).This interval should be set at such a value that a car moving at a speed considered safe for the location will receive the Go signal in time to permit continuing at that rate of speed. Cars approaching at a greater speed will be forced to reduce their speed before proceeding. Vehicle approach interval and unit extension (speed control with intersectional control).-The vehicle approach interval and the unit extension should be set in accordance with the foregoing suggestions. The maximum period on the main street should be set in accordance with the suggestions previously given for adjustment of the maximum period. Cross-traffic periods (not speed monitoring) should 1)(' adjusted as in any traffic-actuated control with time extension. Interval adj1lstments for volume-density controllers.-The minimum initial portion should be set at a value that will permit a few cars to pass through the intersection before its expiration. A larger number of vehicles will need more time than this minimum initial portion and 8ince the detectors are far enough away from the intersection so that a large number of vehicles can be between the detector and the inter8ection, provision must be made for lengthening the initial portion. The number of cars that can pass the detector before the minimum initial portion starts to increase should be the number that can move into the intersection during the minimum initial portion. Each car above this number will cause additional time to be added to the minimum initial portion. The amount of time added by each car is called "increase of initial portion per car" and should be set at such a value that, under heavy traffic conditions, waiting cars will clear the intersection before the expiration of the minimum initial portion plus thc increase thereof. Streetcar and bus actuations are sometimes weighted 80 as to affect the controller in the same manner as would several passenger automobiles. The passage time 8hould be set at a value that will permit a ('ar crossing the detector on the green indication to elear the intersection 194 before the expiration of that green indication if the vehicle is moving at a reasonable speed. This can be set long, because if traffie conditions are such that this long period should not be granted, a shorter period determined by requirements of traffic will automatically be substituted therefor. In this type of control the timing is responsive to several traffic conditions, including the following: 1. Number of cars waiting on cross street. 2. Time that cross traffic has been \Yaiting. 3. Time spacing of vehicles on street with Go signal. As the number of cars waiting at the red indication increases, the duration of the unit extension on the street having the Go signal is simultaneously decteased, thus requiring denser traffic in order to hold the Go signal thereon. As the numher of cars waiting at the red light increases, the extendible portion on the other street is reduced until the low limit sct on the controller is reached. The time to which tlw extendihle portion can he reduced, as well as the number of cars waiting against the red light required to cause such reduction. call be adjusted independently for each street. Thu." the control ('Ollstantly balances the numher of cars waiting 011 the Stop signal against the density of the traffic moving into the Go signal in allocating the rightof-way. A platoon of cars erossing the detector on the main street can reduce the extendible portion of the Go interval on the noss street so markedly that it \\'ill secure preferential treatment and pa"s through the interseetion without delay. The controller also keeps traek of the time "pacing het\n~ell ('an; approaching the Go signal and if ('ro"s traffic is waiting gives the rio signal to the other street "'hen some preseleeted amount of straggling occurs. If the pattern of approaching traffie gives an average spacing between cars of 1 second, the unit extension time on that street i" automatically set slightly in execs" of 1 second. When the main bod~' of the platoon of ears has passed and ears begin to approach at intervals considerably greater than 1 second (in other words, to straggle), the right-of-way will be transferred to the cross street, if traffic is \vai ting there. If the average time "pacing of cars approaching the Go signal is 2 or 3 seconds, the control \\ill automatically set thp unit extension at slightly greater than 2 or 3 s('('.onds, again operating to transfer the right-of-way when straggling oeems if there is waiting eross traffic. This effect is adjustahle on two dials. One of these sets the minimum time to which the extension limit can be redueed by the rate of traffic flow, and the other sets the rate of traffie flO'v \\hich will reduce the extension period to the set low level. Lntil the low level j" reached, the more frequent the approaching traffic on the Go signal, the shorter the extendible' portion for that indication will be'come. The features described above work together to recognize both the approach and clearance of a platoon of vehicles and to operate the signals so as to facilitate these movements. Intervals for one-way restiicted zone controls.-The timing of the initial portion, the unit extension, and yellow clearance interval is the same for a one-way restricted zone signal control as in any trafficactuated signal having extendible portions. The all-red clearance interval should be set at a value that will permit a car which has crossed the detector to elear the restricted area before the Go signal is given in the opposite direction. Interval Sequence Traffic-actuated intersection controllers should provide time intervals for any desired combination of signal indications. The sequence of intervals for each traffic phase should be fixed so that the various intervals will always appear in order when the signal indications on that phase are changed. Equipment for standard traffic-actuated control (speed control excluded) at intersections should provide any of the standard color sequences. Sequences are limited by the number of intervals available in the controller and the wiring of the controller to the signal heads, so that they are fixed except as they can be changed hy rewiring or, of course, by the replacement of the controller. Interval sequence for traffic-actuated speed control signals can he varied for the application. Typical sequences provide for a normal red indication which changes to green, yellow, or flashing yellow after termination of a vehicle approach period. After the expiration of an extension period, or periods, the signal indication automatically returns to red. Speed control with traffic actuation at a two-movement intersection causes the signal to operate as a modified three-phase signal. Two of the phases correspond to the two approaches of the speed-controlled street and these may, of course, operate in unison. The third phase handles the cross street. Controllers actuated by pedestrian detectors may provide distinct pedestrian intervals, with WALK and WAIT indications, as a part' of the signal sequence, or they may simply provide a green indication for the street being used by the pedestrian in the same manner as would actuation by an automobile of a vehicle detector on that street. Rotation of Phases The rotation of intervals with traffic actuation is determined by demands of vehicles and pedestrians. With simple two-phase operation, the various color sequences are provided in fixed order as the controller responds to the actuation on the two streets. While the se- 196 quence of intervals is always the same, the duration of intervals is governed by traffic demands. With three- or four-phase operation, intervals for each phase will be initiated only when the demand exists, and the duration of intervals is governed by traffic demand. If there is no demand for one -of the phases, that phase is omitted in the rotation of phases. 1m F-SPECIAL PEDESTRIAN SIGNALS Definition Special pedestrian signal~are highway traffic signals erected for the exclusive purpose of directing the pedestrian to take some slwcifi(. adion. Warrants Special pedestrian signals should be installed in conjunction ,,'j til traffic signals already meeting one or more of the minimum warrantii previously set forth in the sections on fixed-time or traffic-aetuated signals, under the following conditions: 1. When pedestrians and vehicles move during the same phaiie and the pedestrian volume crossing the major street averages at least .500 persons per hour for any 8 hours of an average day; or 2. When a separate phase is provided for pedestrian movement in all directions (as at a T intersection or traffic cirde). all vehicles being stopped; or :3. 'Vhen heavy vehieular turning movements require a separa Ie pedestrian indication for the protection and convenien(~e of the pedestrian desiring to cross the street; or 4. 'Vhen pedestrian movement on one side of an intersection iii permissible while through vehicular traffic is stopped to protect a turning movement on the other side of the intersedioll; or 5. When a separate phase is made available for pedestrians in til(' operating cycle of a traffic-actuated signal; or 6. When a traffic signal is installed solely for the benefit of pedeiitrians, as at a fadory entrance or a school crossing, even though the volume in warrant Xo. 1, above, is not equalled or exceeded. Special pedestrian signals should not ordinarily be installed at school crossings where schoolboy patrols can be used effectively or where students can be directed to cross at 10('ations already controlled by signals or police officers. However, they may be warranted at an intersection used as a school