58. Street Railroad Tracks.—Where railroad tracks exist on the streets, the sub-grade and the pavement foundation shall extend under the tracks, uninterrupted except by the ties and other structures connected with the track. Where concrete foundation is used, special care must be taken with the concrete directly under or around the rails, and concrete made of fine crushed stone and a higher ratio of cement and sand may be required in contact with the rail. The concrete must be thoroughly tamped under and against the rail.
The asphalt surface shall be laid directly against the rails, which, if their temperature be under fifty (50) degrees F., shall be heated by suitable appliances to a temperature of, or above, sixty (60) degrees F. immediately before the asphalt material is placed around the rail. The hot asphalt material must be thoroughly tamped against and along the rail and under any projecting portions of it, and the surface of the pavement must be even with, or slightly (not more than one-eighth (⅛) inch) above the top of the rail. Slot-rails will be treated in the same manner, subject to such modifications as their forms may necessitate.[[25]]
59. Plant.—The plant for making asphalt paving mixtures must be of approved modern design, adapted to do the work properly, and equipped with efficient machinery. It shall be of sufficient capacity to turn out at least twelve hundred square yards of pavement surface daily without crowding. Weighing and measuring devices shall be accurate and adapted to the purpose, and must be frequently tested and adjusted. Each plant must be supplied with the apparatus necessary to make all determinations and tests required at the plant to properly conduct the work in accordance with these specifications. Steam-rollers must be properly balanced and the rolling surface must be true and smooth. All the street tools used must be of approved kind and quality and must be kept in good working order.
ASPHALT BLOCK PAVEMENT
60. Sub-grade.—The sub-grade for asphalt block pavement shall be prepared as specified in Sect. 26 of these specifications.
61. Foundation.—The foundation for asphalt block pavement shall be hydraulic concrete or broken stone.[[26]]
Concrete foundation shall be constructed in accordance with Sections 28 to 37 inclusive of these specifications and shall have a thickness of ... inches.
Broken stone foundation shall be constructed in accordance with Section 40 of these specifications and shall have a thickness, when completed of ... inches.
62. Asphalt Blocks.—Asphalt blocks shall be not less than ten (10) inches nor more than twelve (12) inches long, not less than four (4) nor more than six (6) inches wide and not less than two (2) inches nor more than four (4) inches thick. Blocks for the same street must be of the same standard size throughout and individual blocks shall not vary in any dimension more than three-sixteenths (³⁄₁₆) inch from the standard size. Blocks that are chipped, cracked or are otherwise defective shall be rejected.
63. Material and Composition.—Asphalt paving blocks shall be composed of crushed trap rock[[27]] or equally hard and durable rock, sand, pulverized stone and asphaltic cement.