
I've got an idea.
Why don't they just fill the train cars with water and change the system so that people jump in from above so they don't have to fill the train car at every station? They just need to give every passenger a personal pressurized air tank and scuba-diving valve. That would also serve as a ticket. And it would prevent freeriding - no air tank, you're screwed.
Water is almost equal in density with human body. Thus in water, the force exerted to body in crash would be almost completely countered by lift provided by the water. In fact, if a human has lungs full of air, he or she usually floats, so in a crash people woould be moving
backwards as the water would move past them, keeping its original vector.
AS double bonus, the water would most likely prevent any serious fires as well as work as shrapnel protection in these dangerous, dangerous times of errant bombers running about.
Seriously though. Saying that packed train is safer in a crash is quite ludicrous. It is physically accurate statement in itself, but doesn't take into account the fact that it only applies to the fast deceleration effect in crashes. Subsequent fires would have all the more impact when evacuation sites were clogged with unconscious and/or injured people. Same applies to every other problem situation other than just the impact phase of a crash. Fire, someone having a cardiac arrest, someone dropping a baby in the floor, etc. etc. ad infinitum. And obviously, a packed car is all the better target for all those errant suicide bombers.
