This usually doesn't happen when you ride inside a passenger car:
http://www.foxnews.com/us/2012/08/31/trapped-man-leg-amputated-in-utah-train-yard/?test=latestnews
http://www.foxnews.com/us/2012/08/31/trapped-man-leg-amputated-in-utah-train-yard/?test=latestnews