36 BULLETIN 407^ U. S, DEPAETMENT OP AGEICULTTJRE, 



States Department of Agriculture, located about 3 miles north of 

 Miami, The roadway is 1,725 feet long and is 12 feet and 16 feet in 

 width. The traffic to which it is subjected is light, and originates on 

 the grounds of the experimental gardens. 



The site is a new location, which was cleared, grubbed, and graded 

 immediately before the surfacing was undertaken. After leaving the 

 Miami-Lemon City Road, the first 600 feet was a deep sand bed, 

 while the remainder was a succession of ridges of coralline rock, with 

 sand beds intervening. The coralline ridges were excavated, and a 

 uniform sand subgrade was prepared. 



The surfacing materials used were coralline rock and a heavy 

 asphaltic oil. The properties of the rock as it occurs near Miami are 

 noted in U. S. Department of Agriculture Bulletin No. 105. The sub- 

 grade, which was 6 inches thick, loose, was built of coralUne fieldstone 

 gathered on or near the site of the project, sledged on the subgrade 

 and thoroughly rolled. 



The rock for the wearing course was taken from a county pit about 

 1 mile from the road. The fine material resulting from blasting was 

 eliminated by screening the rock over one-fourth inch stationary 

 screens. The wearing course was 3 inches thick, loose, and was rolled 

 once over with an 8-ton macadam roUer before the bituminous ma- 

 terial was apphed. The cross section of the road shows a crown 

 sHghtly less than one-half inch per foot. 



The properties of the bituminous material are stated in Table 39. 

 This material was dehvered in barrels, heated in 1-barrel kettles, 

 and appMed by means of hand-pouring pots. From 1 to 3 hours 

 after it had been poured the bituminous material was covered with 

 about one-haK inch of sand which had been taken from the roadside 

 and screened to remove twigs, roots, etc. The sanded surface was 

 then rolled until all visible movement of the surface particles ceased, 

 after which the road was opened to traffic. 



The cost of the various processes involved in the construction of 

 this section are given in Table 40. The cost data are based on labor 

 and material as follows : 



Superintendent, per day $4. 00 



Foreman, per day 3. 00 



Teams, per day 5. 00 



Labor, per day 1. 50 



Roller, per day 6. 00 



Bitumen, per gallon 2 134 



