Oli 
BULLETIN 5S6, U. S. DEPARTMENT OF AGRICULTURE. 
Experiment Xo. 6 — Water-gas tar preparation, hot application. — 
The re-treatment of this section in November, 1915, put the surface 
in first-class condition and at the time of inspection it showed little 
wear, no breaks, and only a few small areas where moisture had per- 
meated the mat. In general, the surface remained in fine condition. 
Experiment Xo. 7 — Asphaltic petroleum, cold application. — As con- 
templated in the last report, this experiment required re-treatment 
early in July, 1916. The characteristics of the bituminous material 
used are given in Table 52 and the quantities and cost data are given 
in Table 53. At the time of inspection the surface was in good con- 
dition for the season. It had not become so muddy as usual and the 
mat was much more uniform. Traffic census had been continued, 
regular counts having been taken for a 24-hour period every thir- 
teenth day. A tabulation of the maximum and average of each class 
of traffic for the calendar year 1916 is given in Table 55. Traffic south 
of the census station is on experiment Xo. 1 only; that north of the 
station is on experiments Xos. 2 to 7, inclusive. Maintenance by 
patrolmen was continued during the year and Table 54 shows com- 
parative cost data to December 31, 1916, for the various experiments 
included in this project. 
Table 55. — Volume and character of traffic on 
Roctvi 
lie Pitt 
Section 1. 
Sections 2 to 7. 
Maximum. 
Average. 
Maximum. 
Average. 
Xorth 
bound. 
South 
bound. 
Xorth 
bound. 
South 
bound. 
Xorth | South 
bound, bound. 
Xorth 
bound. 
South 
bound. 
1 
2 
Loaded 1-horse wagon 
Unloaded 1-horse wagon 
30 
17 
46 
15 
s 
22 
2 
IS 
31 
20 
41 
6 
3 
21 
1 
2 
21 
71 
110 
793 
55 
42 
18 
7 
28 
4 
1 
1 
12 
9 
14 
14 
13 
1 
...... 
22 
8 
29 
6 
5 
4 
11 
1 
1 
7 
57 
3 
82 
611 
41 
n 
17 
14 
28 
5 
1 
14 
1 
1 
16 
61 
3 
87 
700 
46 
10 
4 
6 
2 
5 
7 
3 
4 
Unloaded 2-horse wagon 
4 
1 
6 
Unloaded 4-horse wagon 
7 
5 
5 
g 
q 
10 
U 
74 
23 
105 
694 
66 
16 
5 
17 
2 
50 
209 
40 
5 
6 
19 
1 
50 
216 
32 
13 
2 
15 
3 
11 
15 
I 9 
Excessively heavy vehicle 1 
IS 
34 
158 
23 
3 
33 
14 
Motor touring car 
164 
15 
Loaded motor drav 
23 
16 
12 12 
i Very heavy vehicles, such as carry ore, stone, timber, machinery, etc. 
WASHINGTON, D. C, 1912. 
TAR PREPARATION AND OILS, SURFACE TREATMENT. 
The original report of these experiments was published in Circular 
No. 99 of the Office of Public Koads, and inspection reports have 
appeared in Bulletins Xos. 105, 257, and 407, U. S. Department of 
Agriculture. The following report describes the maintenance during 
the year 1916 and the condition of the experiments March 28, 1917. 
