Utah Code § 56-1-18: Injury to passenger riding outside regular cars.

In case a passenger on a train of a railroad company shall suffer personal injury while riding on the platform of any car or on any baggage, wood, gravel or freight car in violation of the company's printed regulations posted at that time in a conspicuous place inside its passenger cars then in such train, or in violation of verbal instructions given by any officer of such train or company, the railroad company shall not be liable for such injury provided at the time it had furnished and had available room inside of its passenger cars then in such train sufficient for the accommodation of the passengers.