No person shall stop, park or leave standing any vehicle on any Harbor Department roadway other than parallel with the edge of the roadway heading in the direction of traffic and with the right hand wheels of the vehicle within eighteen (18) inches of the curb line or edge of the roadway except upon those roadways which have been marked or signed by the Harbor Department for angle parking, upon which roadway vehicles shall be parked at the angle to the curb indicated by such marks or signs.