This one is interesting, in light of some of the recent accidents......
http://www.fra.dot.gov/eLib/Details/L18294
It is an interesting concept, but years of a mentality of denial in the RR industry, where avoiding litigation, often meant ignoring obvious dangers, lest the RR might be held legally liable for them, when something later happened, if they had already admitted these dangers even "might" exist, has been a stumbling block......?