54 
BULLETIN 407, U. S. DEPARTMENT OF AGRICULTURE. 
Tables 54 and 55 show comparative cost data to date for the various 
experiments included in this project. 
Table 54. — Surface maintenance costs of 1913 experiments on Rockville Pike, Mont- 
gomery County, Md., to December 31, 1915. 
Total 
Surface 2 
Total 
cost i 
main- 
cost of 
Surface 
Total 
Ex- 
per 
tenance 
surface 
main- 
main- 
peri- 
ment 
Bituminous material. 
com- 
pleted. 
Length. 
square 
yard 
per 
square 
per 
square 
tenance 
per mile 
tenance 
per mile 
No. 
prior to 
vard 
yard to 
per vear 
for 
Jan. 1, 
during 
Dec. 31, 
1915. 
1 vear. 
1915. 
1915. 
1915. 
1913. 
Feet. 
Cents. 
Cents. 
1 
Refined coal tar (hot) 
Sept. 22 
9,060 
12.34 
15.36 
S27. 70 
§1,129.90 
§1,486.49 
2 
Refined water-gas tar 
(cold) 
Sept. 24 
4,425 
9.55 
9.34 
18.89 
137 81 
202 22 
3 
Asphaltic petroleum 
(cold) 
Sept. 30 
7,400 
9.05 
11.37 
20.42 
401 20 
529 25 
4 
Residual asphaltic pe- 
troleum (hot) 
Oct. 15 
7,100 
11.28 
3.93 
15.21 
170. 20 
276.73 
do 
Nov. 21 
6,775 
11.30 
4.02 
15.32 
141 78 
226 68 
6 
Water-gas tar prepara- 
tion (hot) 
Nov. 26 
6,325 
11.71 
15.82 
27.53 
1, 200. 48 
1,270.93 
7 
Asphaltic petroleum 
(cold) 
Dec. 5 
6,689 
10.03 
10.38 
20.41 
828.84 
894.24 
Average for trap and gravel. 
2 To December 31, 1915. 
Table 55. — Materials and cost data for surface retreatments in 1915 on Rockville Pike, 
1913 project. 
Sec- 
Bituminous material. 
Area 
of 
section. 
Quantity of material per 
square yard. 
Cost per square 
yard (cents). 
tion 
No. 
Bitum- 
inous 
material. 
Gravel. 
Sand. 
Bitum- 
inous 
material. 
Gravel. 
1 
Refined coal tar, hot application 
Asphaltic petroleum, cold application 
Water-gas tar preparation, hot appli- 
Sq.ft. 
15,000 
7,400 
10,542 
11,148 
Gallons. 
0.425 
.165 
.474 
.204 
Cu. yds. 
0.014 
Cu. yd. 
0.038 
.014 
0.043 
3 
0.016 
6 
.018 
7 
.011 
.022 
Bituminous material. 
Cost per square yard (cents). 
Sec- 
tion 
No. 
Sand. 
Cleaning 
surface. 
Applying 
bitu- 
minous 
material. 
Applying 
sand or 
gravel. 
Super- 
vision. 
Total. 
1 
Refined coal tar, hot application 
0.003 
.002 
0.007 
.008 
0.015 
.005 
0.003 
.005 
0.109 
3 
6 
Asphaltic petroleum, cold application 
Water-gas tar preparation, hot appli- 
0.036 
.070 
i.lll 
7 
.023 
.001 
.006 
.004 
.002 
.058 
1 Work done by contract. 
