OFFICE OF PUBLIC KOADS. 71& 



cubic yard at the quarry. The total cost per square yard ran from 53.7 cents 

 for the oil-asphalt experiment to 60 cents for the refined coal-tar experiment. 



The total cost to the community for the entire section was $1,215, which is at 

 the rate of $6,486 per mile for a 20-foot road/ 



OILED-ASPHALT GRAVEL EOAD. 



Ames, Iowa. — The road selected for bituminous construction at Ames, Iowa, 

 was an old gravel road in the grounds of the State agricultural college. The 

 work was begun on September 19, 1910, and finished on October 12, 1910. The 

 road was 300 feet long, with an average width of 27 feet. The old gravel sur- 

 face was about 6 inches thick. It was prepared for treatment by working with 

 a disk harrow for a depth of 2 inches. Fresh gravel was then applied and 

 spread with a road grader until the road was well shaped, after which it was 

 harrowed with a spring-tooth harrow until the coarse material appeared on 

 the surface. The oil-?spbalt was heated in kettles to about 300° C. and ap- 

 plied at the rate of lA gallons to the square yard. During the application the 

 bitumen cooled without penetrating satisfactorily, and, consequently, the road 

 was saturated with water from a hose and again worked with a disk harrow, 

 in which the disks had been reversed. By this means the bitumen was worked 

 into the gravel to a considerable extent. After the road had dried out it was 

 rolled with a 10-ton steam roller until smooth. In all, 900 square yards were 

 finished, at a cost of 2.2 cents per square yard for preparing the surface and 

 15.5 cents for applying the asphalt. The total cost of the work per square 

 yard was 17.8 cents, which amounted to $160 for the 900 square yards treated.' 



OILED-GRAVEL MACADAM ROAD. 



Boise, Idaho. — This road is a continuation of Ninth Street, running south 

 from the Boise River to Morris Hill Cemetery. The report covers tJie residence 

 of the engineer sent from this office from August 6, 1910, to September 8, 1910 

 The road is 7,262 feet long and 16 feet wide for the first 5,163 feet and 20 feet 

 wide for the remainder of the distance. The subgrade was very dusty and 

 the No. 1 stone was placed directly on this dust for a depth of 6 inches, filled 

 with sand, and rolled with a 12-ton steam roller. The foundation course was 

 river gravel, ranging in diameter from 2^ inches to 1^ inches, and 50 per cent 

 of it had been crushed. A wearing course of crushed gravel, varying in diameter 

 from H inches to one-half inch, was next applied to a depth of 2^ inches loose; 

 this was rolled and remained some time before the oil arrived In the mean- 

 time, therefore, the wearing surface was harrowed before the oil was applied. 

 The data concerning the oil treatment deal with 1,671 feet only, beginning at 

 a point 428 feet from the Boise River Bridge. The oil came from Port Rich- 

 mond, Cal., and was furnished under specifications from this office; its cost 

 was 2 cents per gallon, but the total expense, including the freight charges, 

 raised this amount to over 11 cents per gallon. The oil was heated in the 

 tank car and run into a distributing wagon of 500 gallons' capacity, fitted with 

 steam pipes. It was spread with a patent distributor at the rate of 1.75 gallons 

 to the square yard. Sand was then spread over the road and the surface was 

 rolled. In all, 3,713 square yards were treated, at a total cost of 28.83 cents per 

 square yard. The labor cost $2 and teams $5 per day of eight hours.' 



OILED-GRAVEX EOAD. 



Las Ceuces, N. Mex. — This road is the campus driveway at the New Mexico 

 College of Agriculture. The work commenced on August 11, 1910, and was 

 finished on October 15, 1910. The road is 3,410 feet long and is graded for a 

 width of 30 feet. The surrounding country is rolling and the subsoil is sandy. 

 The excavation cost $90.50 and was done with plow, slip scrapers, and road 

 machines. The foundation course, 16 feet wide, was an adobe clay applied 4 

 inches deep. Seven hundred cubic yards of this material were used and hauled 

 for a distance of 1,500 feet. The cost per cubic yard of this work was as 

 follows: Loading, 9 cents; hauling, 20 cents; and spreading, 2 cents. After 

 the clay had been spread, the roadbed was thoroughly wet by irrigation, at a 



1 More complete details of this work may be found in Office of Public Roads Circular 

 No. 94. 



» Further details of this work are described in Office of Public Roads Circular No. 94. 



