GEOLOGICAL SURVEY OF GEORGIA
S. W. McCALLIE, State Geologist
BULLETIN No. 24
A SECOND REPORT
ON THE
PUBLIC ROADS
OF
GEORGIA
BY
S. W. McCALLIE
State Geologist
.ATLANTA, GA.
CHAS. P. BYRD, State Printer 1910
PREFATORY NOTE
In submitting this report on the public roads of Georgia to the public the writer wishes to express his thanks to the State Pr~son Commission for valuable assistance in the co-operative work of collecting data on the roads of the State. Special thanks are also due to Capt. Goodloe H. Yancey, Secretary of the Prison Commission, who rendered invaluable aid in compiling the statistical data. In addition to the assistance here accredited, the writer wishes, furthermore, to express his gratitude to the various public road officials throughout the State for information concerning the public roads of their respective counties.
This report is the second report on the public roads of the State published by the State Geological Survey. The first report was issued in 1901. This report may, in a measure, be considered an abridged form of the report of 1901, with the addition of a large amount of statistical data brought up to date with additional matter added. It is to be regrett~d that the statisitcal data which were collected by correspondence with the county road offidals had to be estimated, in many cases, however, they are thought to he sufficiently accurate to give a fairly trustworthy idea of the general conditions of . the public roads of the State.
THE ADVISORY BOARD
OF THE
Geological Survey of Georgia
In the Year 1910
(Ex-Officio) Hrs ExcELLENCY, JOSEPH 11. BRO\VN, Governor of Georgia
PRESIDENT oF THE BoAnD
HoN. PHILIP COOK___________________ Secretary of State HoN. J. P. BROWN______________________ State Treasurer lioN. vV. A. \IVRIGHT---------------- Comptroller-General IIoN. JOHN C. HART ___________________Attorney-General IIoN. T. G. HUDSON _________ Commissioner of Agriculture lioN. J. M. POUND ________ Commissioner of Public Schools
LETTER OF TRANSMITTAL
GEOLOGICAL SuRVEY oF GEoRGIA,
ATLANTA, .Tune 15, 1910.
To FEis Excellency, JosEPH M. BRowN,, Gove1rnor, and President of the Advisory Board of the Geological Survey of Georgia.
SIR: I have the honor to sulJmit herewith a second report on the Public Roads of Georgia, to he published as Bulletin No. 24, of this Survey.
Very respectfully yours, S. W. !1o0ALLIE, State Geologist.
T.~.t\BLE OF CONTENTS
Page
PREF.ATORY NOTE_---------------------------------------- 7------
9
MILEAGE, EXPENDITURES AND OTHER PUBLIC ROAD DATA __________ 11-16
ROAD-BUILDING :MATERIALS OF GEORGIA___________________________ 17-23
Road-building materials of the Paleozoic area_------------------ 17-20 Knox dolomite _________________ ---------________________ 17-18
Chickamauga limestone___________________________________ 18
Bangor limestone _______ - _____ - ______ -_~_________________
18
Chert __________________________________________________ 18-19
Shale_________________________________________________ ~ _ 19
Sandstone----------7----------------------------------- 19-20 Road-building materials of the Crystalline area__________________ 20-22
Granites-_-_-_-_---------------_-----------_-------_-___ 20 Gneiss__ -_-_-_-------_-_-----------------------------___ 20-21 Diorite_________________________________________________ 21 Trap or diabase _________________________________________ 21-22
Road-building materials of the Coastal Plain __ - ___ -_____________ 22-23 Limestone------------------------~--------------------- 22 Gravel_________________________________________________ 23 Clay___________________________________________________ 23
RoAD CoNSTRUCTION _________________ ---- ____ --- __ --- ____ .:.______ 23-37 Location of roads_____________________________ ------_________ 23-25
Grades----------------------------------------------------- 25-26 Drainage--------------------------------------------------- 26-28 Road Surfaces ________________________________ -------_---___ 28-37
Stone--------------~------------------------------------ 28-30 Gravel _____________________________________ -.-----_---_-- 30-31 Sand-clay_________________________________ -_- ____ ------- 31-37
Public. Roads of Georgia
MILE~ti_GE -~ND EXPENDITURES
The statistical table of this report shows that the estimated public road mileage of the State of Georgia in 1909 was 82,182. Of this mileage, 554 miles were surfaced with stone and 56 with shells; 502 miles, with chert and gravel; and 3,421 miles, with sand-clay mixture. In addition to these more highly improved r,oads, there were also reported 13,156 miles of road which had been put in order by the use of the road machines, drags, etc. Omitting the 13,156 miles of roads which have been only partially improved, we still have a total of 4,533 miles of road surfaced with stone, shells, gravel, chert, and sand-clay mixture, which constitute about five per cent. of the total road mileage.
Of the 146 counties of the State, 107 employ convicts and 39 use statute or hired labor, the total number of convicts employed being 4,579.
The expenditures on public roads and bridges in 1909 were $1,437,652 property tax, $558,328 commutation tax and $61,000 bond issue, a total cash expenditure of $2,056,980. To this sum should be added $450,000, the estimated money value of the statute and the free labor employed in the State on the public roads. This makes the grand total for all road expenses for the year $2,506,980. In comparing the total road mileage of the State with the total estimated road expenditures it will be seen that each mile of public road cost last year $30.51 or $1.08 per inhabitant based on the census of 1909.
PuBLic RoAD DATA OF GEORGIA QoLLECTED BY THE. STATE GEOLOGICAL SuRVEY IN Co-OPERATION wi'lH THE STATE PRISON CoMMISSION.
MILEAGE .OF ROADS.
COUNTY
IMPROVED ROADS.
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Appling _________ Baker___________.
583 '366
600 -- -- -- -275
Baldwin _________ Banks __________
250 335 216 -- _300
15 69 s-c $ 400 35 50 s-c 300 30 . 175 --------
10 --------
Bartow ____ Ben Hill __ -~ ~~ ~~
485
1 ,000 250
50
60
--s-c
---2-o-o
Berrien _________ Bibb ____________ Brooks__________ Bryan __________
254 463 427
1 ,200 500 450 600
20
20
5 s-c .500
200 300 --------
200
400
53
100
Bulloch _________ Burke __________
930 _883
900 700
50 700 s-c 400 400 300 s-c 400
Butts ___________ 179 300
--------
Calhoun _________ Camden _________
276 718
210 -- -- ---- -- ---
275 10 -- -- -- ---
125 --------
275
250
CampbelL _______ 205 CarrolL _________ 486
465 800
-- --
12
--
--
--
--
---
-----
--
30
----
--------
2,000
Catoosa _________ 171
Charlton ________ Chatham ________
1063 400
200 200 220
---
--
--
1
30
-- --
105
-- ---- -------
--
--
-- --
30
-- --
--------
100 3 ,500
Chattahoochee ___ 231 262 ---- -- -- -- --- -- -- -- --------
Chattooga _______ Cherokee ________
326 434
1
350 ,000
----
-- --
-- --- -- -- -- -- -- -- --
10 2.5
250
Clarke __________ 159 147 8
38 50 s-c 650
:a LABOR USED .s
IN ROAD IM- ::l
PROVEMENT. p, ~ 0
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EXPENDITURES FOR ROAD
;:?
IMPROVEMENT
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PROPERTY TAXl.
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I$ 15 $ 60 $ 30 6$ _____ 1 .4oo $ 3 ,342 $ 8 ,5311$24 ,000
20 50 35 65 31 50 60 60 28 . 50 31 70 139 150 53 100 20 ioo 41 150 64 125
25 4 700 650 4,000
35 20 4,500 1 ,000 3,000
25 18 4,500 1 ,000 -------
30 30 7 ,500 2,000 7 ,000
25 14 4,000 800 400
30 -- ---
40 65
600 13 ,000 .
5,000 7 ,500 3,500 -------
30 30 6,000 1 ,200 8,500
25 8 1 ,000 700 1,300
30 34 6,800 1,800 9,000
40 30 6,000 1 ,100 10 ,000
6 ,000 '-- -- --11 ,000 ------
2,810 2,810 11 ,852 11 ,852 23,810 5,952
4,989 ------44,043 5,110
5,125 ------1 ,600 ------10,330 ------7 ,318 -------
a
21 13 16 37
--
--
83 65 75 45
--
--
25
30 30 35
----14
6 23 14
-------
3 ,000
1 ,000 5 ,000 3 ,000
-------
800 ioo 1 ,000 10,000
-------
4,300
2~500
5,000 10,000
---------
9 ,500 2,000 4,444 12,000
-------
850 1 ,500 5,555 12,000
a 22
- - ~--
65
-- --
25
--- --- ---
--------------
-------
100
-------
1 .200
153 100 50 23 4,600 3,000 -------
2.254 ---- --2,167 ------40,000 -------
a -- -- -- -- -- --- ------- ------- ------- --------- -------
a 40
-- --
75
--
--
30
--
---
24
-------
6,000
-------
1 ,500
-------
8 ,000
---------
4,404
-------
2,936
86 125 35 46 11 ,500 6,500 2,500 --:------- -------
rn "d l
8... ..0..
.<:".:1.'ll
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$35,873 10,000 14,000 5,620 30,704 30,162 12,489 49 ,153 13,625 2,900 19 ,330 17 ,318
-------
14,650 6 ,000 14 ,,999 34,000 2,254 3 ,367 40,000
-------------
15,340 b20,000
1.l:!:stimate made on ta:JC returns for 1908.
--
-----~-
Qlay .. ----------- 216 360 ____ ----
7
Qlayton ____ -- --- H2 aoo____ ____ _____
75 s-c 125 ao________
Clinch _____ -- -- - 1077 4oo 10 _________ 1oo ________
Cobb ________ - _- 821 800 15 __ --
6 201m 3,000
Coffee___ .. __ ----- 920 Colqui~t- ____ ---- 565 Columbia____ ---- 306
950---- ---- 30
700 ---- ----
7
350 ______ -- ____ -
6 s-c tlQO
400 s-c aoo 850 s-c 300
Coweta. ____ ---- 443 800
25 150--------
Crawford ___ .:---_ 834 300 ____ -----------------------
Crisp ---- ------- 285 450 ----------- 200________
Dade ___ -------- 188 145____ 10______ ______ ________
Dn wson _______ -Decatur ________ _ DeKalb ________ _
209 766 271
300 ____ -----------------------
1 ,000---- ---- 100 150
50
1 ,300 16 __ -- 15 600 6 ,500
Dodge ___ - __ ---- 495 450 __ __ __ __ 25 350 s-c 350
Dooly______ ----Dougherty___ -- __
400 339
700----- ---- ----350 10_________
500 ---- -- -250________
Douglas ______ - __ 212 400 ___________________________
Early. __ -------- 503 1 ,000 __ ___ __ __ 50 100 s-c 100
Echols ______ ---Effingham _______ _
365 419
175---- ----------------------500 __ -------------------------
Elbert_ _____ ---- 388 700 __ __ __ __ 20 100 s-c 1,400
BmanueL ______ -- 776 1 ,000 __ __ __ __ 40 250 s-c 250
Fannin________ -;Fay'et.te ____ -----
3 9 0 215
200 -- -- -- -- -- -- - -- -- -- -- -- -- -300---- ---- ----- ------ --------
li'loycL __ -- __ ---- 50G 800 10() -- -- ------
30
760
Forsyth_______ -Frauldin ______ _
252 281
600 500 ____ ---
------ -- 7 --~-~
1 17
100
Fulton ______ ---Gilmer ________ _
Glascock _____ - _ Glynn_______ _
1?4 400 300_________ 25 ________
450 1,000
--------------
95 200 ____ ---- 50______
30
468 150 20 ________ ------ s 2,000
Gordon ___ .. __ - _ Chacly ________ _ Greene _________ _
Gwinnett______ _
Habersham ____ _ Hall .. _________ _
387 400 -- -- -- -- -- --- -- -- -- -- -- -- --
453 400 ____ ... --------------------
t!QO 850 31 3 3 ______
200
510 1 ,0001 __ -- ---- -- ---
35 --------
280 4001_'"' ~- ,____ -- ___, _______ -:- __ __
tl49 Goo 8! _______________ ),5oo
---~-~----
18 75 ao 10 2,500. 1 ,000_ ---
4,103 ______ _
48 10 ao 27 6 ,ooo a ,ooo
5 0
2,620 ______ _
a4 40 25 _________________ a,o 0 __________ -------
65 125 35 42 60 ao
34 6,800 1 ,575 7 ,5 0 20 5 ,000 300 6 ,0 0
12 ,443 11 '199 7,366 ______ _
26 60 30 14 3 ,500
800 6 ,5 0 __________ -------
27 60 25 16 3 ,000
900 2 ,0 01
3,591 ______ _
56---- 30 26 6 ,000 2 ,500 8 ,0 0 25,186 4,407
CL _____
2 400 135 ____ _
2,869 ______ _
23 75 25 15 3,000 4,000 2,0 a _______________________________ _
0\
6 '745 -- ---2,327 ------
a. -------- ---------- ------- ---
80 150 40 G5 90 35 25 75 20
81 GO 16
16 ,000 18 ,000
4 ,000
5 ,000 ~10 ,000
2 ,000
10 ,0 5 ,0 6 ,0
0 0 0
43 100 40 23 L1 ,L!OO (3 ,000 10 ,0 0
49 75 35 24 6,000 6,000 3,0 0
a.
------
6 1,300
260 1,9 0
43 75 35 20 4 ,000 9 ,000 7 ,0 0
a. ------------------- -------
13,000 4,000 14,000 7,000
7 ,248. 5,43G 6,383 ______ _ 6,500 ______ _ 3 ,500 ______ _ 16,000 ______ _
20 75 30 34 50 30
L]
~2
1,030 5 ,000
'750 3 ,000
3,0 '1 ,5 001
36 45 25 24 6 ,000 1 ,500 8 ,0 0
a. -- -- -- -- - . - -- -- -- - -- -- -- - -- - - -
65,,0600001 _____-_-_-_--_ 18,000 2,000
20 Ll5 25
53 166 50
8 64
1 ,400 14 ,400
GOO 16 ,000
'7
11 ,0
01
0
2 ,4381 853 22,118 10,397
G, - - - - - - - - - - - - - - - - - - - - - - - - - - -
20 75 35 16 3,600 ___________ _
549 300 37 235 58,750 40,000 8,0 0\ a. ------------ -------------------
35____ 39 100 50
6 4
1,200 350 400 _______
2,1 2,3
01 0
4 ,886 4 ,88,6 210 ,000 -------
842 3,000
1 '100 -- -- -- 6,581 ______ _
a. -- -- -- -- -- --- -- -- -- - -- -- -- - -- -- -
6,000 ______ _
a. --------------------------------
23 45 25
63 60 tl() a ___ __ __ __ a. ________
26 27
6,000 5 ,4~0
1,200 1 ,000
6,0 01 '
4 4
1 , loO 800
150 1,5oo
3 6
,8 ,0
b51
00
5,774 5,774
29,635 4,939 3,000_______ 6,800_______
4,103 3 ,120 3 ,000 31,142 13 ,366 6 ,500
5 ,591
37 ,593 2,869 8,745 2 ,32'7
27 ,000 26,000 18 ,684 16 ,383
9 ,500 5,460 23 ,000
8,600 ]3 ,500 28,000
;) ,991 43 ,515
9,772 218,000
3,842 3,200 8 ,881 6,000
17 ,548 34,574
6,855 12,800
COUNTY
MILEAGE OF ROADS. '
LABOR USED IN ROAD IM-
.;!g":')
PROVEMENT. p.
IMPROVED ROADS.
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EXPENDITURES FOR ROAD
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Hancock ________ 523
Haralson ________ 282
Harris __________ 486
Hart________ -- __ 257
Heard __________ Henry __________
313 337
750 ---- -- -- 25 300\s-c $ 25
500 ---- -- -- ----- -- -- -- -- -- -- --
500 -- -- ---- ----- -- -- -- --------
500 ---- -- -- -----
25 -- -- -- --
310 -- -- ---- 10 -- ---- --------
900 -- -- ---- -----
30 --------
Houston_-,- _____ Irwin ___________ Jackson _________
591 459 460
1,400 -- -- -- --
175 1,000 ---- ----
. 50 800 8-C 50
45 25 s-c 125 10 . 100 s-c 400
Jasper ___ ~-----Jeff Davis_______ Jefferson ________ Jenkins _________ Johnson _________ Jones ___________
Laurens _________ Lee _____________
Liberty _________ Lincoln _________ Lowndes ________ Lumpkin ________ Macon __________ Madison _________
410 395 686 400 258 397 791 436 976 290 455 282 392 278
450 -- -- -- -- -- --- -- ---- --------
500 565
----
----
---
--
--
-----
'100
---- --
400
--------
8-C 250
190 ---- ---- ----- 130 --------
200 -- -- ---- 35 110 8-C 50
600 ---- -- -- 50 100 --------
1,310 -- -- ---- 65 95 s-c 700
800 ---- ---- 10 200 8-C 500
500 ---- ---- ----- -- ---- --- . -- --
900 ---- -- -- -- --- 100 --------
1,250 ---- ---- 60 -- -- -- s-c 700
400 -- -- -- -- -- --- ------ --------
550 ---- ---- 15 ---- -- 8-C 400
950 -- -- -- -- -- ---
10 --------
MMcaDriuoffnie--_-_-_-_-_-_-_--_1324548
300 -- -- -- -- 25
400
100
50 8-C 200 25 8.-c 50
35 $ 75 $ 30 28 $ 5,870 $ 2,500 $ 6 ,500 $ _______ $ 2,000 $ 8 ,500
a ---- -- --
------- 3,000 -------
4,831 -------
4,831
a -- -- ---- ----- -------
24 50 30 12 2,400
500 700
------- --------- ---------
4,600 3 ,750 3,750
-------
12,100
26 75 40 8 1,800 450 ------32 100 30 21 4,600 1 ,100 7 ,500
2,200 750 2,950 6,549 12,281 26,330
40 75 30 26 5,000 1,500 4,000 7 ,000 5,000 16,000
26 75 25 32 75 35
14 3 ,150 1,250 ------19 5,000 2,500 12,000
7 ,500 3,000 1-,0,108 10 ,108
10,500 32,216
a -- -- ---- ----- ------- ------- ------- --------- -- ----- -- -------
a -- -- ----
29
-- --- ------- -------
30 6,200 1,200
------- --------- ---------
6,000 9 ,000 -------
-- --! --
.15 ,000
40 90 35 22 5,000 700 5,500 5,177 1 ,725 12,402
34 100 30 16 2,400 1 ,020 2.766 4,183 2,384 9,333
26 60 30 25 5,500 3,000 4,200 3 :346 2,007 9 ,553
58 100 30 41 10,000 2,000 n.ooo 5 ,883 ------- 16,883
32 85 30 21 4,500 2.000 4,000 4,500 1 ,795 10.295
a - -- ---- -- --- ------- ------- -------
10 50 30 15 3,000 2,500 3,500
3 ,701 ------4,000 -------
3,701 7 ,500
54 85 25 28 6,000 1 ,500 2,500 --------- -------
a -- -- ---- -- --- -- -- --- ------- -------
40 125 30 26 5,000 1 ,000 4,100
2,000 ------10,882 4,000
2,500 2,000 18,982
29 60 30 17 4,300 1 ,200 10,000 3,300 3,300 16,600
15 40 ---- 9 1 ,800 ------- 3 ,600 7 55 30 14 2,000 350 2,500
3,000 4,008
_-_-_-_-_-_--
6,600 6,508
~-~--~-
- - - - - .--~---~-~--
~---~--~-----~----------
---------
Mcintosh________ 429 150 5---- -- --- ------ --------
Meriwether ______ lVliller ___________
544 275
1 ,<100 ---- ---- .__ -50
10 --------
260 -- -- ---- ----- -- -- -- --------
Milton __________ 147 250 -- -- -- -- -- --- -- -- -- --------
MitchelL ________ 542 600 -- --- -- --- 30 200 s-c 200
Monroe _________ 480 1 ,000 -- -- -- -- -- --- -- -- -- -- -- -- ---
Montgomery ______ 642 800 -- -- -- -- ----- 100 --------
Morgan .. ________ 346 1 ,000 ---- -- -- 250 500 s-c 300
Murray _________ 352 250
20
--------
l\1 uscogee_________ 255 400 25
50
--------
Newton __________ 259 250 15
15 11 s-c 500
Oconee__ -~ ______ 184 350 -- -- --- --
2 ______ --------
Oglethorpe ______ 575 940 10 -- -- 50 30 s-c 500
Paulding ________ 329 700 -- -- -- -- ----- ------ --------
Pickens __________ 219 Pierce __________ 518
500 -- -- -- -- -- --- ------ --------
250 -- -- -- -- 10
75 s-c 200
Pike ____________ 294 PollL ___________ 292
900 -- -- -- -- -- --- ------ -------600 ---- -- -- -- --- -- -- -- ---------
PulaskL .. _______ <!77 580 -- -- -- -- 50 250 s~c 22
Putnam _________ 348 350 4---- 20 100 s-c 600
Quitman ________ 152 H.abuh ___________ 344
250 -- -- -- -- -- --- ------ -------400 -- -- ----- -- --- ------- --------
H..:i.ndolph _______ 476 050 -- -- -- -- 106 ------ ---------
H.iehmoncL ______ 272 900 7 100 80 100 g 1 ,600
Rockdale ________ Schley __________ Screven _________ Spalding _________ Stephens __________
121 ]88
654 203 155
238 -- -- -- -- -----
5 s-cl ,200
280 -- -- -- -- -- --- ------ --------
G25 -- -- -- -- 100 350 s-c 100
1 ,000 -- -- ----
5
22 s-c 250
340
15
8-C 350
Srewart _________ 440 6.90 Sumter___ ~- _____ 1534 1 ,150
I:j --------
100 -- ---- s-c 1 ,000
TalboL.- _________ 7 407 '.l'aliaferro _______ 198 TaU.nalL ________ 735 Taylor ___________ 338
414 -- -- -- -- -- --- ------- --------
400 -- -- -- --- -- --- ------ --------
950 -- -- -- -350 -- -- -- --
55 ------ s-c 265 5 ________ s-c 400
Telfair ___________ 412 400 -- -- ---- 50 100 --------
TerrelL __________ 340 800 -- -- -- -- 125
60 s-c 100
a
60 -- --
2 300
75
463 1 ,207 -------
1 .670
44 100 30 26 7 ,000 2,000 10,000 7 ,000 ------- 17,000
11 100 25 10 2,800
450 4,500 --------- --------
4,500
a ---- -- -- -- --- ------- ------- 3 ,000
GOO -------
3,600
41 65 30 3G 8,500 2,000 10,000 14,000 ------- 24,000
30 75 25 26 5,000 1 ,000 5 ,500 10,000 5,000 20,500
26 75 40 22 5,000 1 ,000 6,000 4,850 1 ,375 12,225
32 60 25 2G 6,500 ------- 4,000 --------- -------
4,000
a -- -- ---- -- --- -------
250 -------
4,022 -------
4,022
93 100 35 40 10,000 4,500 3 ,500 33 ,396 ------- 36,896
28 60 ---- 22 7 ,500 2,500 3,500 8,701 4,350 16,551
29 50 30 12 3,000 300 3 ,300 1 ,418 1 ,418 6,136
33 50 30 20 5 ,OOll 1 ,250 7 ,000 6 ,000 ------- 13 ,000
a -- -- -- ---
12 2,700 ------- 6 ,GOO
6,000 ------- 12,600
a 22 53
--- -- -- -- --- ------- ------50 22 2 450 200 85 35 35 7 ,500 2,000
------- --------- ----------
1 ,700
5,951 -------
5,000 9,404 1 ,567
-------
7 ,651 15,971
a
G5 -- -- 27 6,750 2,010 ------- 11 ,000 -------
11 ,000
38 100 40 i31 8,525 1 ,500 5,500 10,000 3,000 18,500
30 90 30 27 G,OOO 6,000 6,750 4,811 3 ,608 15,169
a -- --- ---- ----- ------- ------- ------- ---------- --------
a -- -- -- -- -- --- ------- ------39 G5 30 27 5,000 1 ,000
168 100 40 70 H,OOO 10,000
27 75 35 17 3 ,000 2 '750
4,000 7 ,300
900 3 ,500
2,000 ------5 ,000 -------64,000 ------4,282 4,300
-------
6,000 12,300
64,900 12 ,082
10 75 30 G 1 ,500 300 1 ,GOO 32 75 35 16 3.200 1 ,000 G,500
2,050 ------4,922 2,4G1
3,650 13,883
68 75 35 16 4,000 2,500 5 ,500 9 ,979 11 ,474 26 ,953
24 50 40 16 3,GOO 1 ,500 3 ,000 82 90 25 16 3,000 2,500 6,000
8,G88 ------- ll,G88 4 ,497 2,248 12,745
78 125 35 75 ~6 ,875 G ,000 6 ,500 --------- ------- 50,000
(/, -- -- -- -- -- --- ------- -------
16 50 30 12 2 .400 1 ,000
-------- ------------------
2,700 -- -- --- --- 2,500
-------
5,200
14 60 30 14 3,000 600 a --- -- -- -- -- --- ------- -- --- --30 75 25 14 3 ,500 1 ,500
6,500 9,000 -------
-------- --------- ---------
5 ,000 5 ,G16 4 ,212
' 15 ,500
-------
14,828
45 85 37 29 5,000 800 9,000 3 ,000 ------- 12,000
-----~----
COUN'J'Y.
-
----
-----
------~----
----
MILEAGE OF ROADS.
LABOR USED ~
IN ROAD IMPROYEMENT.
.0 ::I p.
!
:g.;; ~
IMPROVED ROADS.
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EXPENDITURES FOR
~
ROAD IMPROVEMENT.
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PROPERTY TAX.
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tomas _________ 504 600 ---- -- -- 50 300 s-c $ 350 66 $1001$ 30 $ 47 $ 9 ,400 $ 1 ,850 $ 9,000$ 12,500 $__ ---- $ 21 ,500
1ft0_m__b-s -_-_-_-_-__-_-_-_-
271 519
350 -- -- ---- 90 380 ---- -- .... _ -----
40 8-c 200. 34 75 25 12 3 ,000 1 ,000 5,500 20 ------ _._ 26 100 25 16 4,000 1 ,200 3,500
9,300 3,000 5,668 -------
17,800 9 ,168
lWnS- _- ~- ----- 168 :oupe __________ 434 uner ______ -~ __ 326
150 -- -- ---- -- --- -- -- -- -------- a ---- ---- -- --- ------- ------- ------- --------- ------- ----------
()50 -- -- -- -- 15 ------ 8-C 600 39 75 30 19 4,000 2,105 6,322 11 ,550 -------
17 ,872
800
100 200 SC 125 26 75 25 21 4,500 1 ,000 3,000 4,600 2,000
9,600
~'iggs __________ lion ___________
oson __________ 'alker__________ alton__________
are ___________
arren _________
423
325 310
433 366 676 298
300
150 --------
200 ---- -- -- ----- -- -- -- -- -- -- --
. 400 ---- ---- --- ... - ------ -- -- -- --
563 ---- 234 -- ---
42
800
1 ,400
800 --------
300 '325
-------
----- --
--
8
---
--
-- -50
---------------
25 100 30 14 3,500 1 ,000 4,600 1 ,929 964
7 ,493
a ---- ---- -- --- ------- ------- -------
723 -------
723
a a
-------
----- --
---------
-------------
_-_-_-_-1--0-0
-------------
---------
10,000
-------------
---------
10,000
33 100 30 34 6,800 1 ,500 ------- 12,387 4,129 16,516
31 75 35 10 2,000 11 ,500 2,500 --------- ------16 60 30 18 4,500 1 ,000 4,100 --------- -------
2,500 4,100
ashing'ton _____ ayne__________ ebster_________ hite___________ hitfield ________ ilcox__________
wilkes _______ -~ _ wilkinson _______ worth __________
680 766 227 243 285 473 501 431 604
1 ,200 ---- ---- 200 50 s-c 300 55 .85 25 48 9,000 3 ,000 10,000 10,000 18,500
600 -- -- -- --
8
50 s-c 500 a ---- -- -- ----- ------- 5,700 2,500
5,106 2,042
228 ---- -- --
5 85 8-C 1,500 10 65 35 10 2,500
500 5,000
2,629 4,331
250 ---- ---- ----- ------ -------- a -- -- -- -- -- --- ------- ------- 3,300
800 -------
450 5---- ----- 150 -------- a ---- -- -- -- --- ------- ------- -------
8,000 -------
'800 ---- ---- ----- -- -- -- -------- 18 65 20 11 2,000 400 4,500 --------- -------
900 6---- ----- 100 -------- 34 60 30 22 4,000 3,000 6,470 6,918 2,421
500 -- -- ---- ----- -- -- -- -------- 20 40 25 9 2,200 1 ,500 5,000 2,641 3 ,301
800 ---- -- -- -- ---
400
--------
29 100 25
- -----
18 . 3 ,600 1 ,000 10,000
10,000 3,000
38,500
9 ,648 11,960 4,100 8,000 4,500 15,809 10,942 23,000
Total _____
82,182 610 502 3 ,421 13,156 -------- 4,579 -- -- -- -- 2,645 588 ,450 271 ,480 558 ,328 1 ,157,895 279 '757 2 ,056 ,980
~
n-Roads kept up by statute or free labor or by both. b-Total expenditure, includes money raised by taxation and bond sale.
c-"Otherwise improved" are
roads partially improved by road machines, drags etc.
It-The great variation in the cost of sand-clay roads is clue to the width of roaus, amount of grading, etc.
m-l\Iacad!1-mi11ed roads. sc-Band-clay roads.
y-Gravel road5.
s-8hell roads,
BOAD BUILDING 'MATEBIA.LS
17
ROAD-BUILDING MATERL~LS 1
In the discussion of the road-building materi.als of Georgia, it is well to divide the State into three divisions, namely, the Paleozoic Area, the Coastal Plain, and the Crystalline Area.
ROAD-BUILDING MATERIALS OF THE PALEOZOIC AREA
The road-building materials of the last named area, the Paleozoic, which comprises all or a part of ten counties in the northwestern part of the State, consist of limestones, cherts, shales and sandstones.
LIMESTONE.-The limestones of the area are very abundant and well suited for macadamizing purposes. They are divided geologically into three divisions, namely, the Knox do1omite, the Chickamauga limestone, and the Bangor limestone.
TRE KNox DoLOMITE is the most extensive of the three formations. It attains a thickness, in places, of more than 4,000 feet, and occurs in the form of a number of broad belts traversing the area in a northeast-southwest direction, giving rise, usually, to broad, rounded ridges. The formation consists. largely of compact, heavy-bedded, light-gray magnesian limestone, often oolitic and always containing a considerable amount of siliceous material in the form of chert. Its uniform texture and its semi-crystalline structure will adapt it for macadamizing purposes. It would, indeed, be a difficult matter to find a calcareous deposit better adapted for roadmaterial than some of the beds of this formation. The stone is easily quarried and is readily crushed by the rock breaker;
1. For a more complete discussion of the road materials of Georgia, see Bulletin No. 8 on Roads and Road Materials of Georgia, published by this Survey.
18
PUBLIC ROADS OF GEORGIA
but it has, at the same time, sufficient toughness to form a durable wearing surface.
THE O:HICKAMAUGA LIMESTONE overlies the Knox dolomite. It occurs in the form of narrow belts, more or less parallel and often valley forming. The formation is so-called from Chickamauga valley, where, in the neighborhood of Chickamauga Park, it reaches its greatest development. Its various beds differ considerably, both ~n physical structure and mineral composition. In its western exposure it is a blue, fl.aggy, highly fossiliferous limestone with S?me local variations of minor importance. The compact, blue variety of this stone makes an excellent macadam. It has been extensively used for this purpose both at Chattanooga and in Chickamauga
Park. It makes a hard, smooth road surface, comparatively
free from dust. The Chickamauga limestone varies from 1,000 to 1,80D feet in thickness and is the underlying rock in many of the narrow,, fertile valleys in Northwest Georgia.
THE BANGOR LIMESTONE is a pure, dove-colored limestone, attaining a thickness of about 900 feet. It is highly fossiliferous and contains, in places, crinoid stems in great abundance. The formation is well exposed along the flanks of Pigeon and Lookout mountains. The extent of the area covered by this formation is limited mainly to the narrow belts at the base of the above named mountains; and, as a consequence, it will probably never become of very great importance in road construction. However, its use for macadam in the vicinity of Chattanooga shows that it is well suited for that purpos~.
CHERT.-The chert deposits of the ~aleozoic Area are quite extensive and are widely distributed throughout the area. They occur in two' different' geological formations, namely, the I{nox dolomite and the Fort Payne chert, the latter being
ROAD BUILDING MATERIALS
19
the lowest member of the Carboniferous formation. The chert of the Knox dolomite is co-extensive with the dolomite ~tself, and is by far the more important deposit of the two, for road building material. It occurs in the dolomite in the form of nodules, and also in beds, frequently several feet in thickness. In the weathering of the dolomite, the chert remains as a residual product in the form of gray flinty nodules. This siliceous material frequently accumulates to the depth of many feet along the sides and slopes of ridges where it is often well exposed in railroad cuts. The chert is an impure variety of flint, frequently containing more or less calcareous material, an~ is readily crushed into sharp angular fragments. It has been extensively used for several years for surfacing roads and streets throughout North Georgia and Tennessee. The material is well suited for roads of light travel, but where the traffic is heavy it is inferior to limestone. It possesses an excellent binding qual-. ity, but afterlong drought and much travel it becomes some-. what dusty.
SH..&.LE.-The shales of the Paleozoic Area are of but little econQmic importance as road-building materials; howevBr, the shales in the vicinity of Rome have been used to a considerable extent for roa,d surfacing. This material makes a fair road surface; but it is objectionable, on account of its rapid wear and dusty condition during the dry season, especially when there is much travel.
SANDSTONE.-The sandstones of the Paleozoic Area are confined chiefly to Pigeon, Sand, and Lookout mountains. They are known as the Walden sandstone and the Lookout sandstone. The former constitutes the surface rock of the above named mountains, while the latter forms the cliffs and escarpments along thier slopes. The aggregate thickness of the
20
PUBLIC ROADS OF GEORGIA
formation~ is several hundred feet. These sandstones are so easily crushed that they are of but little value for road material.
THE ROAD-BUILDING MATERIALS OF THE CRYSTALLiNE AREA
Th~ road-building materials of the Crystalline Area consist of granite, gneiss, diorite, and trap rock.
GRANITE.-The granite is very generally distributed throughout the Crystalline Area where it occurs in the form of large intrusive masses in the gneisses and schists. These granitic mass~s often coyer hundreds of acres, and occasionally, as in the case of Stone Mountain,. form dome-shaped masses, ha.ving an elevation of seve:r:al hundred feet above the surrounding country. In texture the granites differ widely. The.y vary from an exceedingly fine-grained, homogeneous, monumental stone to a very coarse-grained granite or pegmatite. The fine-grained varieties are quite extensively quarried at ~everallocalities in the State for building and monumental stone; and also for street paving purposes. The physical tests, which have been made on these granites, show that they have great strength, and are therefore among the best of ~this class of stone for road material.
GNmss.-GneiS's is far more abundant in the Crystalline Area than granite; and, as a general rule, it is much more suitable for road material. The gneisses. are divided into two varieties, namely, the true ~neiss, made up of quartz, feldspar and mica, and the hornblende-gneiss, which contains, in addition to these minerals, hornblende as an essential constituent. Hornblende-gneiss is generally superior to the true gneiss for road purposes on account of its finer texture and
greater 'toughness. It occurs, in places, throughout North
Georgia, where ifisfound in narrow belts underlying the .so-
ROAD BUILDING MATERIALS
21
called" red l~mds." The great amount of iron which the rock carries adds probably to its binding quality. It wears well and is comparatively free from dust. The true gneiss makes a fair road-surfacing material, when it is fine-grained and composed largely of quartz. Nevertheless, it is usually inferior to hornblende-gneiss.
DroRITE.-Diorite, which is more or less abundant throughout North Georgia, is a green or dark gray rock resembling very closely in general appearance the hornblende-gneisses. It occurs mostly in the form of narrow belts or zones, intercalated with the gneisses and schists. }.!I:ost of the diorites of the Crystalline .~.L\..rea have a schistose or laminated structure which injures it for road macadamizing purposes. The diorites, when fine-grained and not too distinctly laminated, make an admirable road material, second oJ+ly to diabase. The toughness, hardness and binding quality of this stone are all excellent. Large exposures of this rock are to be seen throughout the Piedmont Plateau.
TRAP OR DrABASE.-Trap rock is very generally distributed throughout the Crystalline Area. It occurs always in the form of dikes, which have ~riginated from the filling of fissures by molten matter forced up from below. The dikes have generally northwest-southeast trend and a nearly vertical dip. They almost invariably cut the gneisses and the schists at a considerable angle, and rarely ever show any evidence of shearing or crust movement since their formation. All the larger dikes of Georgia, so far as known, are usually quite uniform in thickness, and frequently extend for many miles, with but few interruptions. A good example of one of the larger dikes is to be seen in a cut on the Central of Georgia Railway a few miles east of Newnan. This dike continues for about 65 miles in a southeasterly direction through Cow-
22
PUBLIC ROADS OF GEORGIA
eta, Meriwether and Talbot counties, finally disappearing beneath the recent sands about four miles south of Talbotton. c, These rocks are of dark gray or black. color, usually fine~ grained and quite difficult to break with a hammer. As a road-surfacing material, this class of rocks has no equal. Its great hard_n-ess and its remarkable toughness make it an ideal road-building material.
THE ROAD-BUILDING MATERIALS OF THE COASTAL PLAIN
The road-building materials of the Coastal Plain are limestone, clay .and gravel. In the vicinity of the coast, shells also have had limited use in road surfacing.
LrMESTONE.-The limestones of South Georgia outcrop at many points throughout the Coastal Plain. They are exposed most ahun_dantly along the streams and" in the vicinity of limesinks or lakes. . They are also occasionally seen in the cuts of the vq,rious railroads traversing this part of the State. These limestones are usually soft and of a porous nature; though, occasionally, they become quite compaCt and are partly crystallized. The softer varieties, in places, consist mainly of fragments of shells and a limited amount of sand cemented together by a calcareous matrix. This class of limestone has been used to a limited extent for road and street surfacing both in South Georgia and Florida, where it seems to give general satisfaction. It readily cements into a compact, hardened surface, comparatively free from dust. This material has been used in the last few years on so~e of the streets in the city of Macon, where it has given fair re.gults. The hard limestones of South Georgia appear to have had but little use, so far, in road construction; nevertheless, they are more or less widely distributed, and they seem to be fairly well adapted to that purpose. .
ROAD CONSTRUCTION
23
GRAVEL.-Gravel deposits are quite plentiful along the northern border of the Coastal Plain, where they are often seen in thick beds outcropping beneath the superficial layers of sand. The pebbles are all water-worn, and evidently mark the limit of an old shore line. They are often cemented by ferruginous, sandy clays, and make excellent material for road surfacing. Many exposures of these gravel deposits are to be seen in the vicinity of Augusta, Milledgeville, }.1:acon and Columbus. These- gravel deposits are well exposed just across the Savannah River from Augusta, near the Charleston and vVestern Carolina Railway. At this point, the gravel has been extensively worked for the last few years and shipped to Augusta, Savannah and other points, where it is used for both street and road surfacing. The binding material of this gravel is a ferruginous, sandy clay, which readily hardens into a compact mass on being dampened and rolled, forming an excellent road_ surface, which is both durable and free from dust.
CLAY.-The clays of the Coastal Plain and the other divisions of the State are quite abundant and are well suited for mixing sand-clay roads. At nearly all points through the Coastal Plain, such clays can be found from one to three feet below the surface.
ROAD CONSTRUCTION1
LocATION oF RoADs
The first thing to be considered in the location of a new road is the topography of the section through which the road is to pass. Where topographic maps are to be had, they can be used to great advantage in locating the most practical line for the proposed road. When these maps are not accessible,
1. For a more complete discussion of road construction see Bulletin No. 8, Roads and Road Materials of Georgia, published by this Survey..
24
PUBLIC ROADS OF GEORGIA
J
there must be a preliminary survey made, showing the loca-
tion and trend of the streams and ridges, together with the
relative positions of the ebjective points to be reached by the road. Having obtained this desired information, the road
bui1der proceeds to locate the line of road which will best
accommodate the traffic. for which lt is to be. eonstructed. The
easiest gr:;tdes and the shortest distances, consistent with the
cost of construction, together with conveniences and necessi-
ties of the eommunity, all should receive due consideration
. before the line of road is permanently located.
As a general rule, in mountainous or hilly countries, the
best and most important highways are- located along streams or ridges. Each of these locations has its advantages and disadvantages. Ridge roads are often dry and easily drained,,
but the descent of these roads to the valleys below are like-ly
to present difficult problems in securing practical grades.
The location of roads along valleys, on the qther hand, al-
though they may serve to a better advantage- a larger num-
ber of people, is frequently objectionable on account of the
extra expense of keeping up bridges. Even if the line of road
does not cross the main stream of the valley, there are always
,. many small tributaries or deep gorges to be bridged.
One of the most important questions to be solved by the
road builder in Georgia; is not so much the quet:ltion of loca-
tion of new roads as it is of changing the location of roads
already in existence. This is especially true where the roads
were originally laid out .along lot lines or division boundaries
between properties, regardless of grades and other condi-
tions. These mistakes mm;;t be corrected, in a great meas-:
ure, before it will be possible to construct :first-dass roads
with easy grade, throughout the State, at anything like a rea-
sonable cost. The road authorities of the several counties
should by all means see to it that their roads are always prop-
ROAD CCNSTRUCTION
25
erly located before attempting any permanent improvement. Such conditions as these practically prohibit the construction of good roads in many localities until they are re-located. Changing the location of established roads frequently presents a simple problem; but, at the same time, it may save hundreds of dollars per mile in the cost of grading.
GRADES
Grade, as used in highway construction, means the degree of inclination from the horizontal, or the slope of the road surface. The grade is usually expressed either in the form of a simple ratio, as, for example, 1:20, or terms of percentage. The ratio 1 :20 indicates a rise of 1 foot in every 20, or a 5 per cent. grade.
The grade of a road ,should depend, in a large measure, upon the character of the traffic for which the road is to be constructed. If the traffic is heavy and the individual loads
~
are large, it is always advisable to reduce the grade to the lowest possible minimum consistent with the cost of construction. Most road builders place the maximum grade of macadamized roads at 1:20. Such high grades as this, however, should be short, as they overstrain the team and render frequent stops necessary. The tractive force required to m.Qve a given load over a road with a grade of 1 to 30 is nearly three times as great as that required to move the same load over a level road. It is nearly always practicable to reduce the grade of a road to the above maximum limit, even in mountainous regions, by making the line of road sinuous or zig-zag, without greatly increasing the distance between the objective points or the cost of construction. A good example of a mountain road laid out on this plan is the newly constructed public highway extending from Dahlonega to Murrayville.
26
_ PUBLIC ROADS OF GEORGIA
Besides reducing the efficiency of tractive force, steep grades also greatly increase the cost of keeping roads in .repair. It is a well known law of running water, that its erosive power varies as the square of its velocity.; it therefore follows that a slight increase in grade will greatly increase the effective force of this destructive agent. The extra expense in maintaining a road with high grades will frequently aggregate, in a short time, a sum sufficient to pay the entire expense of relocating the road.
DRAINAGE
Drainage rs one of the most important questions which confronts the road builder. Unless a road is .properly drained, it is practically impossible to keep it in first-class condition..Water must be removed from the roadway or it will sooner or later destroy the hardened surface ap.d thus :ender the road imperfect. This is true, not only of common dirt roads, but also of macadamizred 'roads.
Road drainage is divided into two divisions, namely, surface drainage and subdrainage. surface drainage c-onducts the water which falls on the surface of.the road into the side ditches or drainways, while the subdrainage removes the water from beneath the surface.
Surface drainage rs accomplished by giving the surface of the roadway a slight inclination or slope from its center to its sides and is known as ':crowning" the road.
The angle of the slope which the crown of the road should have depends largely upon the character of the surfacing material used; that is, the angle of slope should be greater for permeable, such as ~andy clays, th::m for the more impermeable materials. The usual grade}or the crown of a macadamized road is about 1 in 30; that is, a roadway .30 feet in
Q
width should be six inches higher at the center than at the
ROAD CCNS1'P.VCTION
27
sides. The crown of a dirt road should be somewhat greater; but in no case should it be so great as to cause an undue lateral erosion of the surface from heavy rains. The water, as it flows from the surface of the roadway, should be received in properly constructed drains on either side of the road. These drains should have sufficient slope to conduct the wat8r off as rapidly as it accumulates.
A road propeTly crowned and supplied with suitable side ditches needs no further drainage. In some instances, however, subdrainage is also necessary to secure the proper drainage. The object of subdrainage is not only to remove the water which may penetrate the surface fr.om above, but also to draw off the water which, by lateral seepage, enters the roadbed from below. Subdrainage may be accomplished by the use of either side or central drains. Side drains may be open or closed, and should always have a depth of two feet or more below the surface of the roadway, and sufficient slope to carry off the water. Open drains perform the double office of carrying off both the surface and the underground waters; and, for this reason, they are often preferable to closed drains. These drains, however, on account of their depth and proximity to the roadway, are frequently dangerous and are therefore objectionable.
Closed drains are variously constructed. One of the simplest consists of a narrow, properly graded ditch, about two feet or more in depth, and partly filled with water-worn, rounded stones. In constructing a drain of this character, it is always advisable to place the largest stones on the bottom and the smallest on the top. Such an arrangement gives ample space at the bottom for the free circulation of the water and prevents the washing in of the earth from above. To guard more completely against the filling of the spaces between the stones by earth, it is often best to overlay them
. 28
PUBLIC ROADS OF GEORGIA
with grass or straw before :filling the upper part of the ditch with earth. Where stones are not to be had, a drain can be made of logs, poles, and brush, which will answer all practical purposes.
For a more detailed discussion of the question of subdrainage, including cost, etc., the reader is referred to Bulletin No. 8, on Roads and Road-Building Materials of Georgia, published by this Survey.
RoAD SuRFACEs
The. roadway having been properly graded and drained the next step is the preparation of the surface. This is accomplished by covering the roadbed to the depth of several inches with broken stones, or some other suitable material.
STONE.-When stone is used for .this purp<Jse, it is customary to prepare the roadbed by :first giving it the proper grade and crown, after which the roller is passed over it until the surface is thoroughly. consolidated and hardened. The surface, having been prepared as ab0ve described, is now ready to receive its covering of broken stones.
It is always bes.t to place the .broken stone on the prepared sub-grade surface in two or more layers, in order that it may
be more completely consolidated by traffic Ol! by the use of the roller. The total thickness of these layers should depend both on the character of the traffic for which the ):oad is constructed and, to some extent also, upon the nature of the road ~oundation. If the traffic is heavy and the individual loads are large, the thickness of the road-covering should be greater than when the opposite condit.ion.s exist. Furthermore, even when the traffic is light, the road-covering should be increased in thickness, wherever the foundation is unstable or insufficiently dr~ined. The road coverings vary from 4 to 12 inche~, an average, probably, being about sev.en inches.
EO..tlD CCNSTRVCTION
29
The first layer of stones should be spread as eyenly as possible over the prepared roadbed to the depth of three or four inches, and then thoroughly compacted by rolling. It is always desirable to have the stones as nearly cubical as possible; and, in no case, should they exceed two or thtee inches
in their greatest dimensions. The more cubical the stones, other things being equal, the easier they are to become con-
solidated into a compact mass.
The first layer of stone having been compressed from about six inches to four inches, it is ready for the reception
of the second layer. This layer of stone, in first-class roads,
is usually, when consolidated, about three inches in thickness,
and consists of fragments one and one-half inches and less,
.
.
.
in diameter. As the layer constitutes the actual wearing sur-
face of the road, it is essential that the stone used should be
as hard and tough as possible.
The road covering is finally completed by placing on the
surface a layer of binding material, one-half inch or more
in thickness, which is sprinkled and continuously rolled until it becomes thoroughly consolidated. One of the best and
most satisfactory materials to use as a binder is the chips and dust obtained by screening the broken stones.. When such
material is not at hand, small gravel, sand or loam will answer the purpose. The object of the thin superficial layer is to
form an impervious covering for the roadbed, and; at the same time, to unite the fragments of stone into a perfect
bond.
Having constructed the roadbed as above described, and given to its surface a sufficient crown to conduct the water
quickly into the gutters or side ditches, we have an excellent
country road, and one, if kept in proper repair, that will last for many years, even under heavy traffic. Such roads are
30
PUBLIC ROADS OF GEORGIA
but little affected by the seasons, and they are as serviceable for traffic in winter as in summer.
GRAVEL.-Instead of broken stone, gravel is often used for surfacing material. The gravel used for this purpose
may he either rounded or angular. The rounded pebbles are found in the greatest abundance along old coast lines or
occupying the beds of streams. The angular pebbles, on the
other hand, are the result of a peculiar disintegration of the
. parent rock, and frequently occur, in considerable beds mixed
more or less with clay. The water-worn pebbles are usually quartz, or some other hard rock well suited for wear on a
road surface. Intermingled with the rounded pebbles in the natural bed, is invariably to be found either sand or clay fill-
ing the int.erstices and forming a matrix, which binds the ma-
terials together. The value of a gravel as a road material
depends, in a large measure, upon the nature and physical
condition of the .matrix.
If the matrix consists of sand
.
.
alone, no amount of rolling or traffic will suffice .to compact
the material into a hardened road covertng; but if,. on the contrary, the matrix is made up of a sandy clay, with consid-
erable iron oxide, the. material is. readily consolidated and forms an excellent road surface. A fair idea of the binding
quality of the matrix of a gravel bed can usually be obtained
from an examination of the gravel pit. When the walls of the p:lt stand perpendicular for any length of time, without
signs of disintegration from freezing or other physical cause, the material will be found in most cases to give satisfactory
results on the roadway. Angular, or what is usually called pit gravel, binds read-
ily into a compact mass; and, on this account, it is commonly
. preferred to water-worn gravel. This kind of gravel always contains a considerable amount of clay, which should be separated from it by screening before it is put on the road. It is,
ROAD CCNSTRVCTION
31
furthermore, desirable, in order to obtain a uniform and smooth surface, to remove all the stones having a greater diameter than two inches. When it is not convenient to screen the gravel, the larger stones may be readily removed with a rake, as they are distributed over the surface of the road. . Before the gravel is placed in position, the roadbed should be properly prepared by giving it the necessary crown and by compacting its surface either by theQ roller or by traffic. The thickness of the gravel forming the road covering should be greater than that of broken stones. They should have a total thickness of eight or ten inches, and should be put on the prepared road surface in two or more layers, each layer being thoroughly rolled before the succeeding layer is placed in position.
One of the strongest arguments in favor of gra-vel roaus is the cheapness of construction. If the gravel has to be transported only a short distance, this kind of road covering is inexpensive, and at the same time forms a road surface well suited for country roads, where the amount of traffic is light.
SAND-CLAY RoAD.-A sand-clay road is a road surfaced with a mixture- of sand and clay in such a proportion that when the mixture is compacted it forms a firm surface suitable for traffic. Roads of this class have in the last few years attracted much attention throughout the Southern States by reason of their cheapness and suitableness for common country highways. The sand-clay mixture may be either aneartificial mixture or a natural mixture, but in either case, other things being equal, the relative proportions of the two different ingredients remain the same. It not infrequently happens that common earth roads have for long stretches the right proportioning of sand and clay to make a typical sand-
32
PUBLIC ROADS OF GEORGIA
clay road, in which case it is only necessary to give them the proper drainage and grade to form them into first-class sandclay roads. It must not be inferred from the above statement that any kind of clay 'is equally suitable for the con-struction of sand-clay roads. A. clay, in order to give the best results, should be highly plastic, and at the same time it should shrink but little in drying. In addition to tliese two
physical properties, the clay should also have good slaking
qualities, otherwise- it will form lumps and will not mix readily with the sand.
Many clays, espe?ially the high grade kaolins and fire clays, possess but little plasticity and as a result give very unsatisfactory results when used in constructing sand-clay roads. A. fair idea of the plasticity of a clay may be had by rolling out a small pencil of' it between the fingers and note the. degree to which it w~ll bend before breaking.
Shrinkage is the amount of contraction which a clay undergoes in the process of drying. The shrinkage of the Georgia clays, as shown by a large number of tests made in the Survey laboratory, varies- from 1 to 17 per ce:I?-t. Before using a clay for sand-clay :r;oads, it is always advisable to determine its shrinkage. This may be readily done by making the- clay into small bricklets and noting the degree of shrinkage upon drying. A. clay with a high shrinkage leads to cracking and breaking up of the surface during the process of drying and a corresponding expansion when again wet by rain, conditions highly detrimental to a good road surface.
The rate of slaking of a number of South Georgia's clays, together with the condition of the slaked product is shown by the following tal:>le:
ROAD CONSTRUCTION
,., 3i)
SLAKING TESTS OF GEORGIA 0LAYS1
Time Degree of slaking
Paper clay, Georgia Kaolin Co. . . . . . . . 6 Min. :fine powder
Paper clay, American Clay Co. . . . . . . . 3 min. :fine powder
Paper clay, Atlanta Mining &, Clay Co .. 5 min. :fine powder
Paper clay, Albion Kaolin Co. . . . . . . . . 4 min. :fine powder
Flint clay, Gibson . . . . . . . . . . . . . . . . . . .
no slaking
Paper clay, Butler ................... 4 min. pulverulent
Plastic white clay, Gibson ............ 5 min. :fiaky
W.hite clay, Perry ................... 2% min. lumpy
Fire clay, Copperas Bluff ............ 2112 min. coarse granules
Fire clay, Carr's Station ............ 7 min. :flaky
White, plastic clay, J. T. Hatfield ..... 7 min. granular
White clay, Rico mine . . . . . . . . . . . . . . . 4 min. complete
Pottery clay, I. Mandel .............. 10 min. slightly mealy
Fuller's earth, Twiggs county ........ 20 min. very :fine :flakes
\Vhite clay, Van Buren .............. 6 min. :fine powder
White clay, Carswell, Mcintyre ....... 3a min. slightly granular
\Vhite clay, Chalker . . . . . . . . . . . . . . . . . 5 min. coarse granules
White clay, B:y-ron .................. 5 min. coarse flakes
Terra cotta clay, Aragon.............
splits into coarse flakes, but
does not show complete dis
integration.
The above slaking tests were made by immersing oneinch cubes of clay, previously dried at a temperature of 212 degrees F., in 250 cubic centimeters of water. A slaking test of sufficient accuracy for road building clays may be made by dropping fragments of thoroughly dried clay into a glass of water and noting the rate and the degree of disintegration.
The relative proportion of sand and clay to be used in sand-clay roads may be determined by the following method as given by W. L. Spoon :1
''Two ordinary glass tumblers of the same size are filled to the brim, one with the dry sand to be tested and the other with water. The water is then pqured carefully from one glass into the sand in the other until it reaches the point of overflowing. The volume of water removed from the glass which was originally full of water can be taken as an ap-
1. For a more complete discussion of the physical properties of the Georgia clays, see the Report on the Clay Deposits of Georgia issued by this \:\urvey.
1. Farmer's Bulletin No. 311, U. S. Department of Agriculture, page 10.
34
PUBLIC lW.ADS OF GEORGIA
proximate measure of the VQids in the unit volume of sand
contained in the tumbler. A simple calculation will reduce
this to percentage volume."
(j
These. various tests are only given to enable the road constructor in the beginning to get a rough idea of the material to be used in constructing his sand-clay surface-. By making these simple tests and also by a critical study of the- mixture in a natural sand-clay road, in a short time, the road builder learns to select the material with a fair degree of accuracy without the use of tests.
The methods of building sand-clay roads are variable, depending upon the character of the subsoil and the nature of the material to be used: In the case the subsoil consists of sand, the method of surfacing, after the roadway has been properly drained and graded, is to cover the roadbed with a l~yer of clay from six to eight inches in thickness in the center, thinning gradually to the- outer edge to :five inches or less. g As each load of clay is dumped ~:m the road it s.hould be S!)rea:d uniformly over the surface . to the desired thickness. The surface is now ready for its coating of sand, which should be spread evenly over the surface. Where the clay is not too lumpy, the sand may be allowed to be worked into the clay by traffic, more being added from time to time as it is needed. This method of making a sand-clay r?ad is quite slow, unless the materials are espec1ally adapted for the purpose for which they are used. To hasten the pr.Qcess of mixing the sand and ?lay, often the harrow ana the plow are resorted to. Where this is done, it is best to use the plow and harrow just after a rain, when the surface of the road is in such a condition that it readily works up into a thin mud.
In case the subsoil is clay, the road is :first drained, graded and crowned, as before, when the- surface is loosened up and
ROAD CONSTRUCTION
35
pulverized by the plow and the harrow to a depth of about four
inches. It is then covered to a depth of six or seven inches
with sand, after which the sand and clay are mixed dry by har-
rowing. To get the best results, the road surface should be
again mixed and puddled after a rain and then given the
proper crown by a road machine or a' drag.
These methods are usually employed when the sand-clay
road surcface is an artificial mixture, but when the sand-clay
is a natural mixture the method is somewhat different. The
method of constructing sand-clay roads with a natural sand-
clay mixture, as adopted in Clarke county, and described by
Prof. C. M. Strahan1 in the Engineering Annual of the Uni-
versity of Georgia, is here given:
"First. The grading of the road bed is first done to a
width of 30 feet.
'' flecond. In the center a bed of top soil 10 inches deep
and 16 feet wide is laid. The teams haul over this bed as the
work progresses. With clay foundation, it would be a mis-
take to prepare a trench to receive the top soil.
"Third. The road machine excavates flat-side ditches six
inches deep and four feet wide; throwing the earth as a shoul-
der against the top soil bed, and then crowning the whole from
ditch to ditch.
''Fourth. The construction teams and traffic pass over
the green bed and pack it down chiefly in the center. When
several hundred yards are thus partially packed, the road
machine pulls in the material from the sides and resurfaces
the bed. New top soil is delivered for weak place_s and
/'.
shaped up.
''Fifth. As fast as the grading of the bed is finished, the
1. Engineering Annual, University of Georgia, Vol. IX, No. lOa, June, 1909, pp. 18-19.
3G
PUBLIC ROADS OF GEORGIA
top soil layer "is spread on it.. Thus by the time one-half mile
of road has been graded and covered with top soil, the first
one-fourth mile has undergone considerable packing and re-
surfacing and getting into good shape.
''Sixth. For some- weeks close attention is paid to the new
bed, watching for weak places, doctoring them, maintaining
the grade with new top soil and keeping the 'crown fully up
., to one inch per foot.
''Seventh. ,Wet weather hastens the period of consolida-
tion if followed by a dry spell. When .packed quite wet, the
wheels consolidate the material from the bottom upward. In
dry or moist weather, the top layer only is consolidated and
may cut through at the next rain. A period of wet weather is usually necessar' y for a full packing down of the top soil
into permanent firmness.
"Eight}+. Usually; in two months, a new top soil road-
bed is cop.s9lidated, shaped to its correct crown, and able
the:reafter to withstand the rains and the traffic. Much .-ef the
reshaping aud doctoring of the surfac.e coat -is done at odd
ti:mes incidental to the- main grading work while the teams are
in transit from barracks to the work.''
The cost per mile to Clarke county of putting on this ''top
soil" coat, according to Prof. Strahan's estimate, using convict
labor at 50 cents per day and the county teams at $1.00 per
day, is $400.00.
The material which is used for road surfacing in Clarke
county, designated as "top soil," is a residual sandy clay,
tesulting from. the. weathering o.f granites and granite-like
... .
rocks.. It usually contains. 50 per cent. or more of hard;
coarse residue, consisting of quartz and feldspar, the latter
often partially altered into kaolin. Experience shows that
the best ''top soil'' is found in cultivated fields where the
fine particles of mica are wanting and the clay has the essen-
37
tial plasticity. The results which have been obtained in Clarke county with the natural sand-clay mixture are very satisfactory, and the work fully demonstrates what can be done throughout the Crystalline Area region of Georgia where like material for building sand-clay roads is abundant.
A somewhat different material from the above natuTal sand-clay mixture has recently been extensively used in road construction in Sumter and other counties in South Georgia. The material here referred to is a reddish sandy clay widely distributed throughout the Coastal Plain. It, like the clays of the Crystalline Area, is often partially residual, having resulted from the weathering of the underlying formations. In Sumter county excellent results have been obtained by using the clay directly from the roadway without any previous mix-
ture. The only attention necessary to keep these roads in
first clatils condition, after they have been once properly graded and drained, is an occasional use of the split log drag, which fills up all ruts and washes and at the same time restores the former crown and leaves the surfa~e in a smooth, even condition. These roads, which I had the pleasure of examining a few weeks ago, are what may be termed ideal
country roads, over which from 8 to 10 bales of cotton may
be drawn by a two-horse team with comparative ease. Such roads as those here referred to, namely, 1wads constructed of natural sand-clay mixture, may be found in a large number of other counties of South Georgia. In many places throughout this part of the State, it is true, surface sands occur, in which case artificial sand-clay mixtures must be resorted to, but, fortunately, even here only a few inches, or at most a foot or so, beneath the surface sands generally occurs an abundance of clay suitable for sand-clay mixtures.
BULLETINS OF THE GEOLOGICAL SURVEY
OF GEORGfA.
.. . : . ..
. .
.. '\
1. Marbles of Georgia, by S. W~ McCallie, 1894, 87 pp., 16 pl., and 2 maps.
Out of print.
,
1. ' 1\fri~;p_les of Q-eo;rgiq,. Second Edition, Revised and Enla:uged, by S. \V.
. McCallie, ~~07., 126 pp., 52. p~., and 2 J?aps. Postage, 13 ce1its.
2.' Corundum Deposits of Georgia, by Franci~ P. King, 1894, 133 pp., G pl.,
,. '" 1 niap. Postage, 9 cents. .
"
-3. A P~"Jrt of the vy'.ater.-Powers of Georgia, .by C. C. Anderson and )3. M.
Hall, 189G,;:,~~R:.PP, 10 pl., and 2 map$. Postage, 9 cents. ' .
4. A Part of tl1eno:fd~Deposits of Georgia, by W. S. Yeates, S; W; Me-
. Callie apd ifr~ancis P. :King, 1896, 542 PP; 21 pl.1 and 1 map~ Out
af p~jnJ..
.
.
5. A Part 6 .ithe Phosphates and Marls of Georgia, by S. W. McCallie,
~~9.G;.~9tLpp.: 3 pl. Postage, 7 cents.
6, A Pa,rt of t~e. Clays of Georgi!;l, by Geo. ;EJ. L~;tdd,. ~898, 204. pp.,, 17 pl.
. Postag?; l1 ceizts. ,.
.
. .
1-. ArteSiai1~Well Systeri:fof Georgia, byS.: W. McCallie;' 18~8, 214 'l~p., 7
.
,<
.ttP,:.'31: pl.:, 8. Roads
a,n.d 3:1?-.4.
?\.i:inHPS '/I}ostage 13 cents, Ro~aq.,~Uilding .Materials of
. Ge?rgia,
by
. S.
. W.
. McCallie,
ir'':!f9'01; 26:4'pp:; '.27.p1., and 1 map. Postage, 14 cent's.
... '
.9; :A.,J?,.a~:tJ~~~~~J~:i'a;l).it~s~a:nd Gneisses of Georgia, by Thomas.L; Wa.tso11,
, 190;.2, 3.6,7.,,jp.p.,...32 pl., and 4 ma,ps.. ,Post(tge,JJ1 eents.
. .
1_0.. Ircni Oves';rdf'::'P.Olk, .Barterw arid .Flciyd Counties, Georgia, by S. W. Me-
lp...,.,..,~~'J,~Citae:l:l~ieh>'>1Q.9sQit'Os.;i.l.!,.f).).t..O-u~'pGeppf.,gi8?;,plb.~y
l'map. -Pos'tttge 11 cents.
W T~os, .~,-, ~tson, 19;0-;1,,_)69.
pp.,
: 12. p-1.,
...
.. i and ..lmap,. :P,o.f'~a9,'13c10 cents.
.
.
12: .. c~~lDep_o.sits 6 G~orgi~.1 :PYi-S; W. McCallie, i904, 121.pp.'; 14 pl., anti
~ ; .a_ ~map:: Ed~taiy,e !)':~'C.e?itR:.;;: . _.,. : : :,
.. . ..
1:3. "
_,.Qcb3er!,.pDa.pepso. sitsJ?_oofst~a._Q'.g~~-q~r,'gti/'ac~e,~,ib',j.~',':~r,b.g"~,'.
L.'
W.atsoq,
lQOQ,
81
pp.1
ll
pL~ .,
a.pcl
14. 'Manganese Deposits of Georgia, ~l:i~'I~b,bma:s L. \Vatson;. ill908, 195 pp:.,
: . ._8 pl.; _;and '2 map~. -f,o~tag~..J2 ~~??:t'L .
. ,
13. Uncler~Tound waters of Georgi3:; b~( 1S'l''\-V. McCallie, 1908, 376 pp., 29
. pl:,. and'2-~'aps. Post~ge 2o c.~'J'I,tS.,"f1f'
. .
.
:16. .water..:Powers af Georgia, by: B. M. 'ari'if"M, R.. Ha:ll, 1908, 424 pp.,-.14
.: '., .. p.L, .an.d-1 illllP Posta,ge 21 oill'ts.
.. . . .
17. F_ossit IrolJ. 'Oi~e 'Deposit.s o~ Georgia, by S. W. McCallie, 1908; 199 pp.,
.; ..: '24. pL, and S maps. . Postq,ge 14 cents.
.
.
],.$~,. G~~Y. Deposits of Q:em~gia, by Qtto Veatch, 1909, 453 pp., 32 pl., :and ;3
' map.s. Postage 25 cents.
.
1~). Qold D.eposits of Georgia, by S. P. Jones, 19091283 pp., 8 pT.; and 2
, , : maps. Post-gg;e 16 .cents. .
20.. ]'\f~_n&r;:\1 Wate:J:;S pf Georgia, by_ S. 'fV.. MGCallie.. In .prep,qra.tion~
21. i-M.~r]s and Limestones of Georgia, by Otto Veatch. In preparation.
22. :m:own Iron Gre$ of Gedrgia, by S. W. McCalli:e. In p1ep.arat.ion:
23~ Mineral. Resot\rces of Georg}a, by S. \V, -McCallie, 1910, 208 pp., 20. pl.,
''
24.
and 2 maps. Postage 14 cents.
Public R.oads of Georgia, Second Report, by S. vV. McCallie, 1910, 3G
pages. Postage 5 cents.
,
NQ~Jj:.-For bound copies of Bulletins Nos. 1, Revised, and 6 to 23, inclnsiYe, 3 cents additional postage will be required.