When cars are run on gravity roads by brakes or sprags, the runner shall only ride on the rear end of the last car, and when said cars are ran by sprags, a space of not less than two feet from the body of the car shall be made on one or both sides of the track, wherever it may be necessary for the runner to pass along the side of the moving car or cars, and said space or passageway shall always be kept free from obstructions.
52 P.S. § 70-806