24 
BULLETIN 105, U. S. DEPARTMENT OF AGRICULTURE. 
off to some extent, yielding a mosaic appearance, but, owing to a 
fair penetration obtained with the material used, the stones are 
lield firmly in place by a matrix of fine stone and bitumen. Experi- 
ment No. 3 lias a more rubbery or corky character than any of the 
others, and shows some tendency to become muddy during long 
periods of rain or snow. This tendency is still more pronounced 
on experiment No. 7, but the surfaces of both experiments soon 
become smooth and perfect with the advent of dry weather. Evi- 
dences of frost action and a consequent heaving of the surface were 
noted between station 164 + 00 and station 167 + 00. Between 
station 156 + 50 and station 157 + 50 a 24-inch culvert running 
diagonally under the road broke through. This has been replaced 
with new pipe, and the road will necessarily be resurfaced over the 
area involved. The surfaces of experiments Nos. 4, 5, and 6 are in 
general smooth and firm throughout. There is, perhaps, more 
unevenness throughout experiment No. 5, owing largely to the fact 
that the treatment was so interrupted because of the difficulties 
incident to handling the tank car of foaming material. The surface 
of experiment No. 6 has picked off in a number of small areas through- 
out the crown of the road, and will require immediate repair at 
these points. These defects evidently developed through insufficient 
protection of the bituminous surface with screenings or gravel. 
There has apparently been some settlement in the wheel tracks 
throughout experiment No. 7 and to some extent on experiment 
No. 6. 
Beginning with June 28, 1913, regular counts of traffic on Rock- 
ville Pike were made every 13 days for a 24-hour period. A tabula- 
tion of the maximum and average of each class of traffic for 22 counts, 
covering the period from June 28, 1913, to March 28, 1914, is given 
in Table 29. 
Table 29. — Volume and character of traffic on Rockville Pike at its intersection with 
Bradley Lane. 
Maximum. 
Average. 
Vehicle. 
North- i South- 
bound, bound. 
North- ! South- 
bound. : bound. 
27 ' 24 
14 
10 
14 
15 
1 
1 
13 
2 
2 
6 
15 
2 
20 
81 
7 
2 
14 
26 
25 
65 
4 
4 
22 
4 
6 
18 
43 
5 
44 
200 
15 
25 
57 
28 
5 
3 
29 
5 
6 
21 
35 
18 
72 
225 
14 
9 
10 
3. Loaded two-horse wagon 
23 
7 
1 
1 
7. One-horse pleasure vehicle 
16 
8. Two-horse pleasure vehicle 
1 
9. Rubber-tired horse vehicle 
1 
10. Saddle horse 
7 
11. Motor cycle 
15 
12. Excessively heavy vehicle 
2 
13. Motor runabout 
20 
14. Motor touring car 
86 
15. Loaded motor dray 
8 
16. Unloaded motor dray 
3 
