DUST PREVENTION AND ROAD PRESERVATION, 1915. 
35 
The cost data given in Table 38 is based on unit costs of labor and 
material as follows, and represents approximately the contractor's 
cost: 
Labor: 
1 foreman, per day $4. 00 
1 foreman, per day 2. 50 
Laborers, per hour 0. 20-0. 40 
Teams, per hour 60 
Materials on road: 
Cement, per barrel 1. 32 
Sand for concrete, per ton 55 
Gravel for concrete, per ton 65 
Bituminous concrete on road (estimated), per square yard 40 
Oil asphalt for seal coat, per gallon 10 
Stone chips for seal coat, per ton 1. 00 
Table 38. — Materials and cost data for bituminous-concrete experiments at Washington, 
D. C. 
General. 
Detail. 
District 
of Co- 
lumbia 
specifica- 
tion. 
Topeka 
specifica- 
tion. 
Materials for base, per square yard of pavement 
Cement, barrel . . 
0.115 
.075 
.165 
C 1 ) 
.30 
115 
075 
.165 
0) 
Materials for surface, per square yard of pavement 
Bituminous concrete 
Bituminous seal coat, gal- 
lons. 
Cement used on surface, bar- 
rels. 
Stone chips for seal coat, tons 
.003 
.015 
20.88 
15.16 
4.09 
10.70 
4.43 
10.08 
40.00 
8.90 
.90 
3.00 
1.50 
1.40 
Costs for base per square yard of pavement , in cents 
20 88 
Cement 
15 16 
Sand 
4.09 
Gravel 
10.70 
Costs for surface per square yard of pavement, in cents . 
Header strips in place 
Mixing and laying concrete. . 
Bituminous concrete on road 
Spreading 
4.43 
10.08 
40.00 
8.90 
Rolling 
.90 
Bituminous seal coat 
Chips for seal coat 
Cement on surface 
.40 
Total 
121. 04 
115.54 
i Not determined. 
EXPERIMENTS AT BUENA VISTA, FLA. 
RESIDUAL ASPHALTIC PETROLEUM-CORALLINE ROCK. 
As a result of observation of the behavior of the various experi- 
mental sections built on Biscayne Drive at Miami in 1913, and 
reported in Department Bulletin No. 105, it was decided to construct 
another section similar in all respects to section No. 6, except that a 
heavier asphaltic material, better suited for use with coralline rock, 
was to be employed. 
The work was done on the driveway leading from the Miami-Lemon 
City Road into the grounds of the experimental gardens of the United 
