DUST PREVENTION AND ROAD PRESERVATION, 1914, 33 
still remaining. The oil was almost immediately covered with gravel, 
and finally the entire section was rolled lightly with an 8-ton tandem 
roller. After several days’ traffic a subsequent light application 
of sand was found necessary to absorb the bituminous material that 
came to the surface. The material and cost data for the surface 
treatment is given in Table 24. 
At the time of inspection the section had passed through a long 
spell of unfavorable weather, and its appearance demonstrated that 
the treatment was applied too late in the season. Numerous small 
but deep cup-holes had formed, extending into the water-bound 
macadam, and in general the entire surface had become very muddy. 
Considerable patching will be necessary at an early date. | 
Section No. 11 (Native AspHatt Emuns1on—MacanaM RESURFACING). 
The section has had no treatment since it was resurfaced, and dur- 
ing the past year it has worn very uniformly, so that at the time of 
inspection the large stones were generally exposed over the entire 
surface. There are a few long waves and in a few places the large 
stones have apparently broken under traffic, but otherwise the surface 
is in excellent condition. 
MAINTENANCE DURING THE YEAR 1914. 
In addition to the general re-treatment above described, the patrol 
system of maintenance was continued during the year. Table 25 
presents the total cost of this maintenance and the re-treatments, 
together with the total cost of each experiment to December 31, 1914. 
A traffic census is taken every 13 days for a 24-hour period. A 
tabulation of the maximum and average of each class of traffic for 
_the period between March 1, 1914, and March 1, 1915, is given in 
Table 20. The east side of the road carries outgoing traffic and the 
west side incoming traffic. 
Tapie 24.— Materials and cost data for surface treatment in 1914 of sections 1, 9, and 10 
at Chevy Chase, Md., 1911 project. 
dD 
- Quantity of mate- 
5) rial per square Cost per square yard (cents). 
oH 
Zs yard. 
See- | Bituminous mate- | 8S 3 
tion Seo pee isi lo ie kes Sle lac 
No. 2s Onn D = =a on; 3 r; Tie a ap O'S | 
~ VAR On) So) 2S se hLS | Se ped laos oal ° 
a i LS) Reise) Ae) 30 aio) A So BESIF as to 
BHeH|o isl B gs oO S | 28 PS ind qd as 
S iSSSiES 1 SR |SS|/ER 1 SA] 8 lagsieas) = 3 
oy EPS S| Sarde q = ae q & labklant| oS 5 
< faa) So oD) faa) o to) oO <q <4 aa] aH 
1 | Coal tar, crude Stee 1,581] 0.316] 0.007}.....- DAORS leo SS | shes 14. anos 10. 791] 0. 625)......] 5.042 
9 | Asphalticpetroleum| 761] .209).._-... 0. 0085) 1 672)- 2. Peete TO“S5Gll. 490) e454 se 50 ae 4.709 
VOR EES GOR PMee See nee: 1,013} .476) .011) .0020) 3.807) 2.328) .419| .339| .548| .571] 0.099) 8.111 
1 Includes cost of sweeping. 
