The surface course shall be constructed on the macadam
base course which shall be dry, free from frost, clean, free from loose adhering
foreign materials and properly finished at the time the surface course is
placed thereon. All rolling shall be done with a three-wheel power roller
having a load of not less than 330 pounds per linear inch of tread of rear
wheels. The broken stone shall be spread in a layer of the proper depth, leveled
and then rolled until thoroughly compacted to the proper grade and contour,
and then the surface shall not be used for any purpose until the bituminous
material is applied. The first application shall then be applied at the rate
of 2.0 to 2.25 gallons per square yard of surface from an approved pressure
distributor. While the bituminous binder is still liquid it shall be covered
with a uniform layer of five-eighths-inch or one-half-inch clean dry broken
stone, just sufficient to fill the surface voids and permit of rolling without
backing up, and shall be thoroughly rolled until the material is thoroughly
embedded and there is no perceptible movement under the roller wheels.