60 
BULLETIN 407, U. S. DEPARTMENT OF AGRICULTURE. 
MAINTENANCE DURING 1915. 
Repairs on these experiments, together with the total cost of each 
experiment to December 31, 1915, are shown in Table 60. 
Table 
-Surface maintenance costs of 1912 experiments at Chevy Chase, Md., to 
December 31, 1915. 
Date 
com- 
pleted. 
Maintenance cost of experi- | Total cost per square yard 
ment. (cents.) 
Experiment Xo. 
Area. 
Total for 
projects 
to Dec. 
31, 1914. 
1915 
T t , Construc- 
iotaL tion. 
Mainte- 
nance. 
Total. 
1 1912 
Sq. yds. 
1,498 
1,400 
2,837 
3, 019* 
S3. 25 
3.55 
2.54 
18.35 
20.66 
.41 
S3. 25 186.62 : 0.22 
186.84 
2 ...do 
S4.ll 
1.03 
2.15 
196.20 
3 
Spring, 
1913 
...do 
3.57 1142.12 
20. 50 i 151. 21 
22. 73 i 143. 13 
1. 77 258. 21 
.13 
.68 
.75 
.08 
142.25 
4 
151. 89 
5 
...do 
3,013 ; 2.07 
2, 055 1 - Sfi 
143.88 
6 
...do 
258.29 
1 Weighted average price for different aggregates. 
SUPPLEMENTARY REPORT OF EXPERIMENTS AT CHEVY CHASE, 
1911. 
BITUMINOUS CONSTRUCTION AND SURFACE TREATMENT. 
MD., 
The original reports of these experiments are given in Circulars 
Nos. 98 and 99, Office of Public Roads, and supplementary reports 
appear in U. S. Department of Agriculture Bulletin No. 105, and 
again in Department Bulletin No. 257. The following report is 
based upon an inspection made February 28, 1916. 
Section No.' 1. — Refined Coal Tar, Penetration Method. 
At the time of the inspection this experiment presented a surface 
almost intact, except at the narrowest part on the curve, where traffic 
is much concentrated. Here the mat is wearing off in sections. The 
experiment is becoming somewhat rough along the gutter on the west 
side, due probably to failure of the foundation. A similar condition 
is noticeable in many of the sections of this project. 
Section No. 2. — Refined Coal Tar, Modified Gladwell Method. 
The condition of this section continues about the same as when 
last inspected, except for a slightly increased roughness along the 
gutter edge. 
Section No. 3. — Fluxed Native Asphalt, Penetration Method. 
Wear on this section continues along the line indicated last year. 
Those areas which were without mat at the time of the last inspection 
are quite generally marked with small pits which are adjacent to large 
particles of exposed aggregate. 
