>"And just how, pray tell, would calling the singals on the radio have prevented these accidents?" Several ways. One is that, if Sanchez had felt a responsibility to call the signal at CP Topanga, he might have been paying attention to that, rather than his cell phone.

You are blithely igorant of how human short-term memory works. Contrary to "conventional wisdom", calling signal on the radio gives no clue as to whether it will be remembered and/or acted on. All it guarantees is that the individual complied with an artificial rule, for which he/she can be charged with a rule violation if not called. This in turns shifts the emphasis of the situation to the avoidance of discipline for not calling the signal, with compliance with the signal indication taking a back seat, when it should be the other way around.

What is missing is the work ethic handed down by the old heads: "If you [screw up], take your medicine, we don't want you out here either, you might kill one of us". This has been pretty much destroyed by the railroads' antics since the 1985 manning agreement. In "them days" if you were a screw off, your fellow workers would send a forceful message one way or another. This doesn't happen anymore. Also coming into play are the new-wave, feel-good, PC policies of the HRD departments.

When all is said and done, PTC, ATS, cab signals, calling the signals on the radio, video cameras pointed at the engineer, etc. /will not/ prevent this sort of accident from ever happening again. If you absolutely don't want two trains to hit each other, then don't set them moving to begin with, and move their tracks at least 30 feet apart so when they tip over in the Big One, they don't land on each other. If you want to permanently forestall getting injured while riding a train, never get on one to begin with. The same goes for riding in your car on the freeway, which BTW is far more dangerous than riding a train, by several orders of magnitude (see: [en.wikipedia.org]).