32 BULLETIN 53, U. S. DEPARTMENT OF AGRICULTURE. 
supervise the construction of a series of test sections on the Biscayne Drive, 
about 2 miles north of Miami, for the purpose of investigating the practicability 
of a bituminous-surface treatment for the local roads. These roads have all 
been surfaced with a soft oolitic limestone, known locally as marl, coralline rock, 
or limestone, deposits of which are found in various sections of the county. Six 
separate experiments were made on as many sections of road, and the total 
area surfaced was 2,804 square yards. 
EXPERIMENTAL ROAD AT CHEVY CHASE, MD. 
The work at Chevy Chase is the continuation of the series of experiments 
begun in 1911, made possible through the appropriation by Congress of a special 
fund for carrying on such work. Various experiments in surface treatment 
were conducted on the section of water-bound macadam constructed in the 
past fiscal year. 
In continuation of the 1911 experiments, additional sections were constructed 
upon a section of Connecticut Avenue, beginning at Bradley Lane and extend- 
ing to the loop of the Capital Traction Go's, tracks at Chevy Chase Lake, The 
experiments are six in number, and comprise sections of bituminous concrete, 
concrete, oil-cement concrete, bituminous-surfaced concrete, surface treatments, 
and vitrified brick. Up to date about 16,378 square yards have been surfaced, as 
follows : Bituminous concrete, 2,898 square yards ; concrete, 3,013 square yards ; 
oil-cement concrete, 1,744 square yards; bituminous-surfaced concrete, 4,178 
square yards; surface treatments, 2,490 square yards; and brick, 2,055 square 
yards. 
In addition to the construction of these sections, the entire series of ex- 
periments was also systematically maintained. 
EXPERIMENTAL WORK ON ROCKVILLE PIKE, MONTGOMERY CO., MD. 
A part of the special fund appropriated for experiments in road improvement, 
together with funds furnished by the community, is being devoted to resurfacing 
the Rockville Pike in Montgomery County, Md. This road will be resurfaced 
with limestone macadam throughout its length and the surface will be treated 
with various bituminous materials in conjunction with gravel, trap-rock screen- 
ings, and limestone screenings. The experiments are being made to determine 
the best methods of maintaining macadam roads free from dust. During the 
past fiscal year about 26,675 square yards were surfaced with water-bound 
macadam. 
EXPERIMENTS ON THE AGRICULTURAL DEPARTMENT GROUNDS, WASHINGTON, D. C 
Several sections of driveway on the Agricultural Department grounds were 
given a surface treatment in October, 1912. This work was done on some of the 
same sections which have already been experimentally treated and decribed in 
former progress reports of the Office of Public Roads. A total of 4,485 square 
yards of surface was treated in 1912. 
MEMPHIS-TO-BRISTOL HIGHWAY. 
Work on the eastern division of the Memphis to Bristol Highway from 
Nashville to Bristol, which was started in January, 1912, was continued during 
the first part of the fiscal year 1912-13. The funds raised to defray the ex- 
penses of an engineer under an arrangement made with the oflice were exhausted 
in December, 1912, and connection with the work was severed. 
