OBJECT-LESSON AND EXPEKIMENTAL KOADS^ 1912-13. 3 



Four hundred and ninety tons of crushed limestone, all passing a 3-inch 

 mesh screen and retained on a 1-inch mesh screen, were used in constructing 

 the broken-stone base. This material was spread upon the prepared subgrade, 

 so that the compacted depth was 4^ inches. Sixty tons of sand were flushed 

 into the voids in the broken-stone base by sprinlding and rolling. The bitu- 

 minous concrete was prepared according to the Topeka specifications at the 

 plant of a Washington contractor, and hauled in tarpaulin-covered automobile 

 trucks a distance of approximately 6 miles to the work. The material arrived 

 on the ground at a temperature of approximately 380° F., and was immediately 

 spread upon the completed broken-stone base. It was then rolled, first with 

 a 3-ton tandem roller, and finally with an 8-ton tandem roller, to a compacted 

 thickness of li inches. Pieces of 2 by 4 inch lumber, laid flat at the sides of 

 the road, served as forms to retain the bituminous material during the process 

 of laying and rolling. These were removed, however, upon completion of the 

 rolling and replaced with a sodded earth shoulder. A seal coat of pea gravel 

 and a native asphalt emulsion was finally applied to the surface of the concrete 

 and lightly rolled with a 3-ton tandem roller. The emulsion was applied at 

 tho rate of approximately one-tenth gallon per square yard and the gravel at 

 the rate of 1 cubic yard to every 200 square yards of surface. 



Automobile parkways having a total area of 205 square yards were con- 

 structed of Portland cement concrete mixed in the proportions of 1 part of 

 cement, 2 parts of sand, and 4 parts of crushed limestone. Second-hand 3 by 

 6 inch lumber was set on edge for forms and the concrete was laid and struck 

 off to a depth of 5 inches, after which the surface was floated with a wooden 

 float. 



Seventy linear feet of concrete gutter crossings, having a width of 4^ feet 

 and a total thickness of 6 inches, were constructed. The concrete for the gut- 

 ter was mixed in the same proportion as that for the parkway, except that the 

 top one-half inch consisted of 1 : 2 mortar. The total cost of the road, ex- 

 clusive of drainage structures, was $3,461.56, which is at the rate of $1,211 per 

 square yard. 



The principal items of cost were as follows : Grading and preparing the sub- 

 grade, 2,807 square yards at $0,174 per square yard, $490.12; total cost of 

 stone for the base f. o. b. siding, 490 tons at $1.10 per ton, $539 ; loading and 

 hauling the stone (length of haul If miles), 490 tons at $0,623 per ton, $305.30; 

 sand filler delivered on the work, 60 tons at $1,557 per ton, $93.40; spreading 

 the stone, 490 tons at $0,161 per ton, $79.01 ; spreading the sand filler, 60 tons 

 at $0,106 per ton, $6.36; rolling the broken-stone base, 2,602 square yards at 

 $0,028 per square yard, $59.27; bituminous concrete at the plant, 2,602 square 

 yards at $0.40 per square yard, $1,040.80 ; hauling the bituminous concrete from 

 the plant to the road, 2.602 square yards at $0,032 per square yard, $82.50; 

 native asphalt emulsion on the road, 2,602 square yards at $0,012 per square 

 yard, $32.50; gravel for the seal coat, 2,602 square yards at $0,011 per square 

 yard, $28; forms for the bituminous concrete, $5; setting the forms for the 

 bituminous concrete, $21.15; spreading the bituminous concrete, 2,602 square 

 yards at $0,039 per square yard, $101.75 ; rolling the bituminous concrete, 2,602 

 square yards at $0,024 per square yard, $62.60 ; cement . concrete automobile 

 parkways, exclusive of preparing the subgrade, 205 square yards at $1,237 per 

 square yard, $278.45; cement concrete gutters, exclusive of the subgrade, 70 

 linear feet at $0,868 per foot, $60.75 ; miscellaneous expenses, $58.14 ; and gen- 

 eral expenses, $142.35. The above costs are based on labor at $1.60 and teams 

 at $4.50 for an eight-hour day. 



