As a New Yorker, I am not sure this suggestion is applicable. The transportation system and infrastructure are robust enough that you can usually get home. If you can't, you can probably find a hotel. If you can't do either, that means something on the order of a nuclear bomb going off has happened, and you'll probably need something more than your PSK.

I now live in a small town in the Midwest (oh Lord, get me out of here!), and I carry space blanket in the car in case my car breaks down in the middle of nowhere. Here I also worry -- if a road get flooded, there may not be another way to get home. In NY, one road goes down, and there are plenty of detours.

Also, NYC is generally a safe place -- if you know what you're doing.