(A) Excavation. Excavation shall be made to the required depth of curb, including depth for suitable base under the curb, and the subbase under the base shall be compacted to a firm, even surface.
(B) Base course. This curb shall only be installed on a constructed base of a minimum of 4 inches crushed trap rock, with the interstices filled with approved sand and a minimum of 2 inches of bituminous concrete material. This width shall be wide enough to accommodate the wheels of the laying machine. In no case shall this dimension be less than 3 feet. Below this construction shall be a suitable material
(C) Materials for the bituminous curb. Materials for this work shall conform .to materials as specified for bituminous concrete walks.
(D) Construction of curb:
(1) The dimension and details of the curb shall conform with existing standards on file in the engineering department.
(2) This curb, except for sections under 20 feet in length, shall be installed by utilizing an approved mechanical spreader and screeder machine, and the operator of the machine shall be experienced in this type of work.
(3) Prior to arrival of the mixture on the work, the surface of the pavement or the prepared foundation where the bituminous concrete lip curbing is to be installed shall have been cleaned of all loose and foreign material. The surface shall be perfectly dry and clean at the time the mix is placed and shall be coated with an RC-2 or other approved bitumen just before arrival of the mixture.
(4) Upon arrival at the site, the mixture shall be deposited directly in place or on platforms outside the area on which it is to be spread and shall then be immediately distributed into place by suitable means. The mixture shall be kept clean and free from dirt and foreign materials at all times. It shall be compacted to the required cross section by the use of suitable iron tampers weighing not less than 12 pounds and having a bearing area not exceeding 50 square inches, or by means of a roller weighing not less than 150 pounds per foot of tread. The surface of the lip curbing shall be tested with a 10 foot straight edge laid parallel with the center line of the road and any variations from a true profile exceeding 1/4 inch shall be satisfactorily corrected.
(5) After the completion of the lip curbing, traffic shall be kept at a safe distance for a period of not less than 24 hours and until the curbing has set sufficiently to prevent injury to the work.
(66 Code. § 59.18)