30 BULLETIN 407, U. S. DEPARTMENT OF AGRICULTURE. 
Experiment No. 1+. — The appearance of this section is similar to 
that of experiment No. 3, but the mat is thinner and the limestone 
aggregate of the macadam is slightly but quite uniformly visible 
over the entire section along the central portion of the road. Some 
excess top-dressing still remains along the shoulders. It is probable 
that the section will require re-treatment in the spring. 
Experiment No. 5. — The mat on this section is softer than that on 
sections 3 and 4, but much less leathery than that on section 2. 
The macadam shows through in a few places, but the mat is not 
broken at any point. It is probable that this section will require a 
re-treatment late in the summer or fall. About 300 feet from the 
south end of the section there is an area about 20 feet in length and 
extending nearly the entire width of the road, where the surface was 
rather badly burned as the result of the burning of a blacksmith shop 
and stables near the road. 
EXPERIMENTS ON BRADLEY LANE, MONTGOMERY COUNTY, MD. 
BITUMINOUS MACADAM (PENETRATION METHOD). 
The experiments previously reported for this road have been dis- 
continued because the design was considered inadequate for the 
prevailing traffic. The traveled way was only 10 to 12 feet wide, 
while the road carried practically as heavy traffic as the adjacent 
section of the Rockville Pike. Partly also because of the exceedingly 
poor drainage and foundation conditions, it had never been possible 
to maintain the surface satisfactorily, and it had become rutted and 
was continually breaking into potholes, while the edges were badly 
cut and sheared by traffic. Finally, hi June, 1915, arrangements wore 
made to reconstruct the roadway as a new experiment, and a bi- 
tuminous macadam surface, constructed according to the penetration 
method, was the type of improvement adopted. 
The old surface-treated macadam was scarified, reshaped, and 
widened by the addition of new material to form the foundation 
course for the new surface. The total length of the road is 3,813.5 
feet. The width of the new roadway was made 16 J feet from 
Connecticut Avenue westward for approximately 2,404 feet by adding 
2 \ feet to the south side and 4 feet to the north side of the old surface; 
the remaining distance to Wisconsin Avenue was made 15 feet wide 
by adding 2 J feet to each side of the old surface. In preparing 
the foundation course it was necessary to add 145 tons of new lime- 
stone; and in order to increase the stability of the foundation, 3,646 
linear feet of 4-inch drain tile was used. The drain tile was placed 
under the south gutter of the road at a depth of a foot or more below 
the surface, and is expected to correct the unsatisfactory foundation 
condition referred to in the preceding paragraph. The drainage 
was further improved by cleaning out all existing culverts and 
