Back in the late '70s and early '80s, when the San Diego & Arizona line through Carrizo Gorge was unused due to major storm damage, there were a few people who would ride the rails on homemade carts. These were very simple, lightweight vehicles, basically just a small four-wheeled flat car with a couple of lawn chairs bolted on, powered by a small gas engine.
My brother and I had a close call one evening after sunset. We were hiking the tracks and in the middle of a very long trestle that had no catwalks. Suddenly one of those carts came around the bend. No headlight, and no muffler either. They couldn't see us and could hear us shouting.
We managed to get out on the far end of the beam at the top of a bent, and avoided being knocked off.