No person except those in charge of trips, superintendents, mine foremen, mine electricians, machinists, and blacksmiths, when required by their duty, shall ride on haulage trips, except where by mutual agreement in writing between the owner, lessee, or agent, and the employees, a special trip of empty cars is run for the purpose of taking employees into and out of the mine, or empty cars attached to loaded trips, which shall not be run at a speed exceeding eight miles per hour. No person except a trip rider shall ride on a loaded car, and he shall ride only the front or rear end of the trip.