4 BULLETIN 586, U. S. DEPARTMENT OF AGRICULTURE. 
ments. The excavation of the foundation pits cost $335 64. The 
cost to the railroad company of its portion of the work was $2,588.76. 
Drainage.—Subdrainage, culverts, catch basins, and paved gutters 
were built where needed. 
Foundation or base course.—After the grading was completed, the 
subgrade was brought to its final shape by the use exclusively of 
picks and shovels and by rolling. Al spongy and yielding areas were 
removed and replaced with fresh material as the rolling progressed. 
The foundation for all the experimental sections consisted of a com- 
pacted layer of gravel 6 inches in depth. A sand-clay gravel repre- 
sented by the analysis given in Table 2 obtained from Haney’s pit, 
adjoining the road, was used. All the gravel was weighed at the pit, 
and sample cubic yards loose also were weighed from time to time. 
A total of 5,604.4 tons of gravel was placed in the foundation. The 
average weight of a cubic yard of loose gravel was 3,000 pounds and 
the expansion from the pit to the wagon was 22 per cent. The 
gravel was dumped on the subgrade and spread by hand to a depth of 
8.7 inches. Practically all the stones of size greater than would pass 
a 24-inch screen were removed in the pit or while the gravel was being 
spread on the road. The gravel base was rolled with a 10-ton roller 
and was all in place December 4, 1915. Travel was allowed over the 
base all winter. Before beginning the experimental surfacing, April 
10, 1916, light trimming and reshaping of the base had to be done, 
but no serious depressions or ruts had developed. 
TABLE 2.— Mechanical analysis of gravel for use in foundation. 
Per cent. 
Passing 1-inch screen, retained on #-inch screen.-.....-..----..--+--+----+---- 1.4 
Passing #-inch screen, retained on 4-inch screen.......--...------------------ by 
Passing sich screen, retained on t-inch screen. -=-.-- 2-2. 2 ee 25.7 
Passing 4-inch screen, retained on 10-mesh #ieve.......-...---.-------------- 19.6 
Passing 10-mesh sieve, retained on 20-mesh sieve.-.........--------------- OAC SL 
Passing 20-mesh sieve, retained on 30-mesh sieve.........------------------- 5.1 
Passing 30-mesh sieve, retained on 40-mesh sieve...............------------- 3.2 
Passing 40-mesh sieve, retained on 50-mesh sieve..........-.--.------------- 3.8 
Passing 50-mesh sieve, retained on 80-mesh sieve..-.....-.------------------ ae 
Passing 80-mesh sieve, retained on 100-mesh sieve............--------------- .8 
Passing 100-mesh sieve, retained on 200-mesh sieve........-.---------------- 2.4 
Passing, 200-mesh sie vers.-1 “esses ees Bae asset eck ete Joes bewe 9.0 
RO tala. See etree Te Se Se cen eee ete anne Ee ee eee ee eS 100.0 
Shoulders.—Karth shoulders were constructed 4 feet wide, with a 
slope of 1 inch to the foot. They were rolled and trimmed as the 
surface was completed. 
Guard-rails.—W ooden guard-rails were constructed along the road 
3 feet outside the edge of the bituminous surface at the stations shown 
in Table 3. - 
