I got the idea from Fall Out 3 and Resident Evil 4. Somehow, even in the most horrible of places (and the most unlikely) there will always be power for a train or a computer.

In Fall Out 3, Anton, there are *some* computers that are still intact, even if the other surroundings are completely torn to hell. :] Think of it as a "lucky" spot. Not pristine as the building was before whatever happened to it happened, but clean and operating.

...also, that happens to have another purpose...in Browning's story. :)