[CedarDave]

The problem would likely be that in the city they are electric powered, thus can't move until it comes back on. (I know that some are dual powered (diesel/electric). I suppose they could run a limited number of diesels through the tunnels, but without fans to exhaust, it would get pretty bad in there from the fumes and CO.)

[Diddle E. Squat]

Right, I should have repeated what I said in my earlier post. The problem with Penn Station is that there are long tunnels on each end that require electrics. So I wondered if(and if not, why not) they were running evacuation bus shuttles between Penn Station and Long Island, where the tunnels end and diesels can take over, and between Penn Station and Newark, where diesels can take over. There is also a brand new station that hasn't opened yet(but is basically completed) in Secaucus, that could also be used to transfer passengers from shuttle buses to the northern NJ lines that don't go through Newark.