DUST PREVENTION AND ROAD PRESERVATION, 1916. 69 
KNOXVILLE, TENN., 1910. 
TAR AND OIL PREPARATIONS. 
RESUME OF PREVIOUS REPORTS. 
This experimental road was built in the summer of 1910. The 
work consisted in resurfacing a section of the Rutledge Pike, an 
old, badly worn, water-bound macadam. Before the experimental 
work was begun the old macadam surface was loosened and re- 
shaped. Crushed limestone ranging from 2 inches to three-quarter 
inch in diameter was spread over the road to a depth of 2 inches, 
and rolled. A crown of one-half inch to a foot was used for both 
the foundation and the surface. On this macadam as foundation, 
three experimental surfaces, 20 feet in width, were laid, using bitu- 
minous materials by the penetration method. A very hard limestone, 
known locally as iron limestone, was used in the wearing course of 
all the experiments. The following table indicates the method of 
construction and shows the condition of the experimental sections 
at the time of the several inspections. The tabulation has been 
prepared from reports made by this office and published in Circu- 
lars Nos. 94, 98, and 99, Office of Public Roads, and in Bulletins 
Nos. 105, 257, and 407, U. S. Department of Agriculture. 
