My wife and I went for a “Sunday drive” to see the sights and we ended up at  the overlook at Cajon Pass Summit in the early morning, whereupon we were surprised to see this strange contraption sitting on the mainline. We realized quickly it was a tie laying train getting ready to proceed downgrade. We were very surprised when the train started moving as it was moving at a fast paced walking speed, judging from the personnel inspecting the train as it started laying ties. We watched in amazement and figured out how it worked. Perhaps you will share our amazement after watching the slide show video.