DUST PREVENTION AND ROAD PRESERVATION, 1916. 39 
Table 43. — Materials and cost data for surface retreatment in 1916. 
Item. 
Area treated square yards . 
Quantity of material per square yard: 
Bituminous material gallons. 
Gravel cubic yards. 
Sand do . . . 
Cost per square yard (cents): 
Bituminous material 
Gravel 
Sand 
Cleaning surface 
Hauling materials 
Applying bituminous materials 
Applying sand or gravel 
Supervision 
Total (cents) 
Experi- 
ment No. 1 
(asphaltic 
petroluem). 
7,625 
0.23 
.0114- 
2.52 
2.51 
.10 
.77 
.35 
.18 
.35 
6.78 
Experi- 
ment No. 3 
(coal-tar 
prepara- 
tion). 
13, 235 
0.33 
.0115 
3.06 
3.45 
.41 
.14 
.24 
.36 
Experiment No. 4 — Refined water-gas tar, cold application, similar 
to experiment No. 2 on Rockville Pilce. — This section has not shown 
the initial signs of disintegration characteristic of section 2 of the 
pike, which is troublesome unless cared for by immediate retreat- 
ment. Several intersecting bad roads tended to impair the character 
of the surface near the intersections owing to the clay that was 
tracked on the bituminous surface. The experiment was in good 
condition, but indications were that a second application of tar 
would be required in the early summer. 
Experiment No. 5 — Refined coal tar, hot application, similar to ex- 
periment No. 1 on the Rockville Pike. — This experiment was in gen- 
erally good condition. It suffered a little near the cemetery, owing 
to large quantities of mud being brought upon it from side roads and 
drives. At the time of inspection there was no disintegration. 
Following the same procedure used in connection with the other 
experimental roads, a traffic census was taken on the Falls Road 
for 15 hours every thirteenth day from April 10 to December 31, 
1916. A tabulation of the maximum and average of each class of 
traffic for this period is given in Table 45. Table 44 shows compara- 
tive cost data to December 31, 1916, for the various experiments in- 
cluded in this project. The cost figures in Table 44 include the cost 
of general retreatments as given in Table 43. 
Table No. 44. — Surface maintenance costs >f 1915 experiments on Falls Road, Mont- 
gomery County, Md.,from January 1 to December 31, 1916. 
Length of 
section. 
Area. 
Cost per square yard. 
Mainte- 
nance cost 
per mile 
of surface. 
Experiment No. 
Construc- 
tion. 
Mainte- 
nance. 
Total. 
1 
2 
3 : 
Feet. 
4,575 
4,386 
7,941 
5,718 
5,880 
Sq. yds. 
7,625 
7, 310 
13,235 
9,530 
9,800 
Cents. 
7.77 
12.11 
8.48 
9.63 
10.21 
Cents. 
6.25 
1.07 
9.33 
.10 
.01 
Cents. 
14.02 
13.12 
17.80 
9.73 
10.22 
$550. 00 
94.16 
821.00 
\ 
8.80 
.88 
