Heh, here's the short version.
A bunch of SERE instructors got to debating evasion techniques, and the subject of how best to hop a train came up. If you know the language, you just dress like a hobo and blend in, don't say much. Otherwise, how to do it best?
Two of them try it out, and hop a freight train, trying out various hiding places and taking notes on where the train slows down enough to get on or off, etc. In the middle of a very long mountain tunnel, they realize they're gonna pass out from carbon monoxide if they don't move fwd, so they do. As you'd expect though, one dude slips, falls under the train, and his leg gets whacked off at the knee.
After lying between the tracks as the train whooshed by overhead with hanging heavy pneumatic lines whacking him on the head and shoulders, he puts on a tournequet and rolls over to the access pathway. He crawls towards the exit about a mile away. Sleepy inspector drives inspection truck past once, doesn't stop. Second time by, SERE instructor fires .45 at him to get his attention, and this time he stops. Memo to self - if you don't tie your survival gear to yourself, you lose it the first time you fall. His .45 was tied to his belt.
Inspector gives him a ride to the tunnel exit. He waits for medics. The show up, strap him to stretcher, plug in IV, then waste 20 min trying to figure out how to get him down 15 ft tall rock/gravel mound that the tracks are on. He gets impatient, hops off stretcher, hops down 15 ft mound on one leg, and hops to the ambulance before the shocked paramedics can stop him. Or maybe they were fascinated and afraid that if they tried to stop him, they'd really hurt him worse than he already was.
I think they determined it was "in the line of duty" and medically retired him.