What Bob's talking about is called, in other venues, Defense In Depth. You need All Of The Above; there is no silver bullet that will fix all problems. Unfortunately, US public and politicians always jump on the latest silver bullet, which turns out to be lead after all.

In the case of the oil trains (which have been around for 100 years in some form), the first line of defense, because it applies everywhere, should be to improve the cars for crashworthiness. Also, better enforcement of both railroad handling rules for the cars and proper use by the shipper (placarding, pre-treating to minimize volatiles, etc.) is needed - it isn't reasonable to expect a business to voluntarily increase its costs just because it's nice or a good thing to do even if it's safety-related.

Once you make progress on things that apply everywhere (think: updated software, antivirus, and a firewall on your own computer), there are obvious next steps. You want good track that won't derail the better cars, because even if the cars are armored like battleships something can still get through them (corollary of Murphy's Law). You want crews treated decently in terms of rest and training/support, and operating rules enforced that hopefully prevent crews and dispatchers from accidentally doing something wrong. You want PTC as a backstop for all of that that. Think: firewall and NAT on your router, and possibly at higher levels in the network as well, and making frequent backups stored in multiple places.

Even then, $#&* happens, so you need training of crews and responders to deal with the consequences. And hope that all the other things keep the $#&* from happening where a lot of other people can get hurt. That's life. Sorry. Think: restore from backup.

Cheers!