DUST PREVENTION AND ROAD PRESERVATION, 1916. 
Table 1. — Description of experiments. 
Experi- 
ment 
number. 
L ocation (stations) . 
Stone. 
Bituminous material. 
First application. 
Second application. 
1 1 
1+81 to 17+81 
17+81 to 35+91 
35+91 to 54+55 
54+ 55 to 72+55 
72+55 to 77+55 
77+55 to 82+61 
82+61 to 87+61. 4 
Trap 
Water-gas tar, refined 
do 
Water-gas tar, refined. 
Oil asphalt. 
2 
do 
3 
do 
do... 
Coal tar, refined 
4.. 
.. . do 
Oil asphalt. 
Water-gas tar, refined. 
Oil asphalt. 
Residual asphaltic petro- 
leum. 
52 
6 
Gravel 
do 
do 
Water-gas tar, refined 
Oil asphalt 
73and8... 
Residual asphaltic petro- 
leum. 
i The area from station 0+00 to station 1+81 at the intersection with the Mount Vernon Avenue experi- 
mental road was surfaced with the same kind of wearing course used on experiment -No. 10 of that road 
and is classed with that experiment. 
2 From station 72+55 to station 73+46, 30 per cent of sand was added to the tar. 
3 The gravel for this experiment was a mixture of pit-run gravel from the Haney pit with f-inch screened 
gravel imported from Richmond, Va. 
GENERAL FEATURES OF THE PROJECT. 
Right of way and location. — A new location was made from station 
0+00 to station 21+40, in order to eliminate a railroad crossing at 
grade with the Washington & Old Dominion Railroad at station 
12 + 50. The county of Alexandria secured this new right of way and 
and also arranged for widening the right of way of the old road to 50 
feet throughout its length. The acquired right of way amounted to a 
total of 2.2 acres. All points of curvature and tangency of the new 
location lines were marked with 6-inch concrete bound stones, set 
with the back face center at the point. 
Clearing and grubbing. — Including both old and new location, 5 
acres were cleared and grubbed. 
Excavation. — All excavating was done with drag and wheel scrapers 
and dump wagons. Wherever practicable, fills were made with wheel 
scrapers in uniform layers. Side-hill slopes under new fills were 
plowed. Slopes in cuts were finished 1 :1 and on fills 1 J:l. The road 
was graded to a width of 24 feet, the shoulders being 4 feet wide and 
having a slope of 1 inch to a foot. The side ditches were excavated 
19 inches below the grade of the road. The crown of the subgrade 
was made the same as the crown of the surface f inch to a foot. 
Between stations 63+50 and 86 + 50, 469 cubic yards of earth were 
borrowed. This borrow was made necessary because when the esti- 
mate was prepared, too small an allowance was made for shrinkage. 
In all, 11,384 cubic yards of earth were excavated. 
Grade crossing elimination. — An agreement was made with the Wash- 
ington & Old Dominion Railroad Co. whereby the company con- 
structed, at its own expense, abutments and a bridge span for the 
elimination of the grade crossing at station 12 + 50. By the terms of 
this agreement, the Department of Agriculture removed the prism of 
earth below the railroad and dug the foundation pits for the abut- 
