850 ANNUAL REPORTS OF DEPARTMENT OF AGRICULTURE. 



bitiiniinons niaterinl was then applied, and on this i-inch screenings and dust 

 were spread to a depth of * inch and again rolled. The bituminous material 

 Wiis luMli'd ill a taiilc car etpii]iiipd with steam coils. The steam was supplied 

 by a portable boiler rented for this work. The amount of earth excavated was 

 700 cubic yards, and the amount of surfacing material 1,119.88 cubic yards. 



The priiicipal items of cost were as follows: Superintendence, $137.50; grad- 

 ing and shaping. .$404.28: drains, $85.87; surfacing material delivered on rail- 

 road siding, $i.0;)O.G8: surfacing material hauled from the quarry, $155.58; 

 teaming from railroad to road, $208.00; spreading the surfacing material, 

 fSl.lG; and rolling, including coal, repairs, etc., $251.21. 



Phoenix, Ariz.— The Central Avenue Boulevard runs northward from Phoe- 

 nix through level country to the Arizona Canal. For a distance of 3,250 feet, 

 built in 1910, this road was described in the annual report for that year, but 

 the work was not (inally completed until March 11, 1911. 



The continuation of the work comprised two sections— one beginning i mile 

 south of the northern city limits and extending for f mile; and the other, con- 

 necting with the work done in 1910, 2i miles long. The width surfaced was 

 16 feet. 



The county furnished a road grader, plows, Fresno scrapers, a 10-ton gasoline 

 roller, and an oil atomizer equipped with a gasoline engine. 



The soil varies from adobe to gravelly loam, and the excavation of only 250 

 cubic yards was necessary. The subgrade was irrigate<l and allowed to dry 

 before shaping. The stone used in this work was crystalline schist, quarried 

 and hauled from a point 2 miles from the northern end of the work. The 

 bottom course was built with stone from IJ to ;> inches in size, placed and 

 rolled to make a compacted depth of 4 inches in the center of the road and 3 

 inches on tlie sides. The second course contained stone from 5 inch to IJ 

 inches in size, placed to make a compacted depth of 2 inches in the center and 

 li inches on the sides after rolling. 



The second course was covered with screenings not exceeding | inch in size 

 and including dust, which was then sprinkled with water and rolled. After 

 the binding course had become dry, the surface was swept with wire brooms to 

 remove all loose particles. An asphaltic oil was used for surface treatment, 

 and the oil was heate<l in tank cars witli steam from a traction engine. During 

 cold weather it was found necessary to reheat it immediately before applying. 



An atomizer was used for distributing the oil. The first application of f 

 gallon per square yard was covered with sufiicient screenings to prevent stick- 

 ing to the wheels of the roller during the rolling process. A second applica- 

 tion of i gallon per square yard was made on the following day, and this was 

 likewise covered with screenings and rolled. Traffic was allowed on the road 

 immediately. 



On the f-mile section coarse wash gravel from the irrigation canal was used 

 instead of screenings, and the earth shoulders on this section were oiled 8 feet 

 wide on each side at the rate of 1 gallon of oil per square j^ard. The No. 2 

 course of 500 feet of the northern end of this section was built of calcareous 

 rhyolite tuff, locally called "caliche." This material was very hard when com- 

 pacted and less penetration of oil was obtained. 



Not including the work described in the 1910 report, the principal unit prices 

 were as follows: Excavation, $62.50; quarrying and hauling stone, 6,664 cubic 

 yards, at $2.06 per cubic yard, $13,727.84; oil delivered at railroad siding, $2.10 

 per barrel; contract price for spreading oil, $0,407 per barrel, and for heating, 

 $0.30 per barrel; gravel used in place of screenings, $1.50 per cubic yard; spread- 

 ing screenings and sprinkling, $0.20 per cubic yard; shaping subgrade, $0,025 

 per square yard ; and conveyance of engineer, $200. The total cost, including 

 one-third the cost of equipment for depreciation, was $24,950, which, on the 

 basis of 30,595 square yards surfaced, is equivalent to $0,815 i)er square yard, 

 or $7,650 per mile. Labor cost $2.25 for 10 hours; and teams, $4.50. 



Including the work done in 1910, the various items are as follows: The work 

 was begun on February 15, 1910, and completed on March 11, 1911 ; the length 

 was 3.875 miles; the width, 16 feet; the area surfaced, 30,.375 square yards; the 

 area of the shoulders, 13,786 square yards; the area graded, 90,937 square yards; 

 and the stone used, 8,100 cubic yards. The principal items of cost were: 

 Machinery, $2,922.73; stone, $9,187.44; quarry site. $850; tools, $700.15; roller 

 repair.s, $850; oftice expenses, $373.94; and labor, oil, etc., $17,440; making a 

 total of $32,324.26. After deducting two-thirds the cost of machinery and tools 

 and leaving one-third for the estimated depreciation, the remainder is 

 $29,909.02, which is equivalent to $0,822 per square yard, or $7,718.45 per mile. 



