That's a big city

So, I'm putting together a post-apocalyptic action-adventure scenario for my group. Trying to get away from the complications of too-high expectations for "artsy" roleplaying by creating a "shoot everything that moves" bit of action for awhile.

So, it's fifty or so years since the evil AI took over the planet and blew half of it up. Mad Max and Terminator are my inspiration, with a glance at GURPS Reign of Steel. (RoS is overly complicated. They threw in a double-handful of competing AIs and all these vastly different zones so there'd be something for everyone.) All the background really isn't that important… the main thing is, there are two or more competing massive AIs, lots of robots still trying to suppress mankind, and cities blown to bits, more or less.

The scenario goes something like this…

The heroes belong to a small village outside the Dallas area. They live underground, farm a little, and hunt and gather. But they're getting too large… eventually the robots are going to discover their village, and they don't have enough supplies. To top it off, several villagers have contracted a disease, and the doctor thinks he can do something about it… if only he can get the right lab equipment. And hey, he used to work for Baylor Immunological Research Institute in Dallas. The heroes are the small team of people given the last of the ammunition, the last of the gas, the only mobile vehicles,

Too much real world information encroaches. I pulled up Google Earth and looked at Dallas. BRI is just about smack-dab in the middle of the industrialized area. Throw in suburbia, and there's miles of what used to be inhabited city. I figure vast swathes have been bombed out or otherwise reduced to rubble, but still… that's a lot of city.

I think this kind of preparation was easier when I didn't have so much information and could pick real places to base my adventures off of. I find a lot of inspiration looking at the map and satellite imagery. But it seems so overwhelming to zoom in on the building I want to be the focus of a big confrontation, and then zoom out, and out, and out, and out, and still not see a place where a village could be established "outside" the now-inhabited zone.

I think the real problem is that I can imagine a scene around, say, a viaduct… but the players could choose to get there by another route. I think that's it… there are so many routes they could choose, even if I bomb 90% of the city into oblivion, that I can't set up location-specific encounters very well. And I like to plan in advance… I'm not terribly good at making up stuff on the fly.

(And I'm thinking out loud when I should be going to bed. I'm not looking for elaborate suggestions to fix my problem, though comments are welcome.)