DUST PREVENTION AND ROAD PRESERVATION, 1916. 59 
CHEVY CHASE, MD., 1911. 
BITUMINOUS CONSTRUCTION AND SURFACE TREATMENT. 
The original reports of these experiments are given in Circulars 
Nos. 98 and 99, Office of Public Roads, and supplementary reports 
appear in Bulletins Nos. 105, 257, and 407, U. S. Department of 
Agriculture. The following report is based upon an inspection made 
February 21, 1917. 
Section No. 1—Refined coal tar, penetration method.—Except at the 
narrow part of the section where traffic is much concentrated, this 
surface presented an excellent appearance. The wear has been even 
and a uniform, slightly mosaic condition prevails. At the curve the 
ageregate was exposed quite generally and a few shallow patches were 
needed. It appeared probable that a re-treatment of this portion 
with about 0.25 gallon per square yard would be required in the 
spring. The gutter on the west side of the section continued to give 
trouble and is responsible for a slight roughness at this place. 
Section No. 2—Refined coal tar, modified Gladwell method.—The 
condition of this section continued satisfactory. The slight roughness 
along the gutter edge noted in the last inspection report had not 
increased, and except for a strip about 4 feet wide on the track side 
of the section, the surface was in practically perfect condition. The 
4-foot strip required a little patching and would be benefited by a 
re-treatment. 
Section No. 3—Fluxed native asphalt, penetration method.—The 
wear on this section, noted as being somewhat irregular last year, 
was much more even and the experiment is conspicuous on account of 
the uniform condition over the entire cross section. Only a few large 
stones were noticeable throughout the surface. 
Section No. 4—Gilsonite oil-asphalt, penetration method.—The south 
end of this section did not require the heavy patching expected last 
season and continued in fair, but uneven, condition. The north end 
is heavily patched, especially along the track side. The mat con- 
tinued in about the same condition as last year, but the surface was 
somewhat more uneven than that of section No. 3. 
Section No. 5—Oil asphalt, penetration method.—The east and west 
parts of this experiment were much more nearly alike than in 1915. 
The east side has failed just as the west side did; heavy patching was 
needed. The west side continued intact as a result of the patching 
done, but both sides were rough and wavy. 
Reeion No. 6—Oul asphalt, penetration PK. —The east side of 
this experiment continued generally better than the west side. On 
the west side about 60 feet south of the Chevy Chase Club entrance 
there were two breaks through the surface, but the corrugations near 
the gutter had not increased and the surface otherwise was intact. 
Tt was much smoother than that of No. 5 throughout the traveled way. 
