Every holder of a permit to operate, maintain or use any spur tracks over and along any street or sidewalk in this City and County is hereby required whenever notified by the Department of Public Works, by written notice, to pave the area between the rails and for two feet outside thereof and between such tracks, if there be more than one, as may be located 15 feet or less apart center line to center line for the entire length of the street used by the track or tracks, except where said tracks are in separate ownership, in which case the cost of said paving shall be equally divided. The type of pavement used shall be as specified by the Department of Public Works. In case the roadway of a street should be repaved with another type of pavement than that formerly used, the portion of the roadway occupied by the railroad track or tracks shall be changed on order of the Department of Public Works.