No operator shall allow a vehicle to stand backed to the curb when loading or unloading, except when it is impracticable to load or unload it while standing parallel to the curb, but no vehicle may completely block the passage of another vehicle or street car by remaining backed up to the curb. When necessary to back up to the curb, the towing vehicle in any combination of vehicles and the horse, if the vehicle is horse drawn, shall stand as nearly parallel as practicable to the curb and facing the direction of traffic.
N.J.S. § 39:4-79