I'm sorry but I run a police garage and the tow driver just bought a truck, once he cut those straps he is now responsible for the vehicle. As to the train they can be stopped just got to call the railroad and let them know that the tracks are blocked, and it is even easier when the railroad co. is standing there. I can't count how many times we/I have had to call Union Pacific and tell them that the tracks are blocked. You would be correct in assuming that the railroad would not want to hit the truck and is even more of a reason that in contacting them that they would not let a train run down the tracks. In todays world even a tow driver must take care in recovering a vehicle, if there is any damage beyond what would have been required to remove the vehicle YOU WILL BE HELD RESPONSIBLE FOR SAID DAMAGE. Considering motorcycle straps were the only thing holding the truck from falling I think a heavy tow truck and a winch line would have easily pulled it back up, but hey that's just my opinion and 30 years of  experience. I admit that I was not there and could not really say for sure, it would have been a judgement call for the driver but he should have not cut the straps period.