DUST PREVENTION AND ROAD PRESERVATION, 1915. 
occurred in three pits adjacent to the road, namely, the Zimmerman 
pit near station 18 + 00, the Garfield pit near station 95 + 00, and the 
Haney pit 1,500 feet to the right of station 116 + 00. The free haul 
of gravel was fixed at 1 mile and overhaul was practically negligible. 
The gravel was excavated by means of a steam shovel and distributed 
in rows from dump-bottom wagons. Stones over 2\ inches in 
size were raked out at the pit or during the spreading. The gravel 
contained 8.5 per cent of water and weighed approximately 3,000 
pounds to a cubic yard, measured loose in a dimensioned box. Gravel 
from the Zimmerman and Haney pits, which were cross-sectioned, 
increased about 20 per cent in volume when loosened. The loose 
depth necessary to obtain the requisite compacted depth of 6 inches 
averaged 7.92 inches and the weight per station averaged 58.5 tons. 
The spreading was controlled by means of 6-inch blocks and lines, 
and the gravel was rolled with a 10-ton roller. The mechanical 
analyses of the gravel are shown in Table 3. 
Table 3. — Mechanical analyses of gravel used for foundation course. 
Zimmer- 
man pit. 
Garfield 
pit. 
Haney 
pit. 
Passing 2-inch, retained on lj-inch screen 
Passing l£-inch, retained on 1-inch screen 
Passing 1-inch, retained on j-inch screen 
Passing ^-inch, retained on J-inch screen 
Passing i-inch, retained on J-inch screen 
Passing |-inch, retained on T yiach screen 
Passing 10-mesh, retained on 20-mesh screen . . 
Passing 20-mesh, retained on 30-mesh screen . . 
Passing 30-mesh, retained on 40-mesh screen . . 
Passing 40-mesh, retained on 50-mesh screen . . 
Passing 50-mesh, retained on 80-mesh screen . . 
Passing 80-mesh, retained on 100-mesh screen . 
Passing 100-mesh, retained on 200-mesh screen 
Passing 200-mesh screen 
Per cent. 
11.2 
4.6 
5.0 
9.1 
11.4 
8.5 
5.2 
3.6 
2.6 
4.3 
8.6 
1.1 
6.7 
18.1 
Per cent. 
Per cent. 
1.3 
8.9 
11.3 
17.2 
13.3 
4.8 
5.8 
8.3 
7.3 
5.4 
.5 
2.8 
13.1 
1.4 
15.7 
25.7 
19.6 
10.1 
5.1 
3.2 
3.8 
3.2 
.8 
2.4 
9.0 
100.0 
100.0 
100.0 
The base of Section II (station 153 + 50 to station 192 + 00) was 
an old bituminous-macadam surface. It was scarified and reshaped 
without difficulty. Where excess material was found it was used to 
stiffen the shoulders immediately outside the new surface. Where 
a deficiency of material occurred, new 1^-inch broken trap rock 
(passing a 2J-inch screen and retained on a 1 J -inch screen) was sup- 
plied. An average depth of about three-quarters of an inch of such 
stone was added to the penetration course continuously from station 
153 + 50 to station 158 + 50, and from station 187 + 00 to station 
190 + 50 a layer 4 inches deep, loose, was used to stiffen the base. 
The entire base, with added stone, was thoroughly rolled with a 
10-ton roller. 
The base of Section III (station 192 + 00 to station 235 + 50) was 
an old "water-bound" trap-rock macadam surface badly out of 
shape. It had apparently been repaired with limestone. It was 
