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 lioxir 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, 



B.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 



(1) 

 .30 



0.115 



Sand, ton 



.075 





Gravel, ton 



165 



Materials for surface, per square yard of pavement 



Bituminous concrete 



Bituminous seal coat, gal- 

 Tons. 



Cement used on surface, bar- 

 rels. 



Stone chips for seal coat, tons 



0) 





.003 



Costs for base per square yard of pavement, in cents 



.015 



20.88 



15.16 



4.09 



10.70 



4.43 



10.08 



40.00 



8.90 



.90 



3.00 



1.50 



1.40 



2088' 



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 





Rolliag 



.90 





Bitummous seal coat 



Chips for seal coat 











Applying seal coat 







Cement on surface 



.40 











Total. 



121.04 



115.54 









1 Not determined. 



EXPERIMENTS AT BUENA VISTA. FLA. 



RESroUAL 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 



