I don't know how subway systems are intended to react during disasters - mostly I assume they'll stop until the track integrity can be checked and obstructions cleared, then if there is power they will continue to run (as long as there are train operators). I know in King County the objective is to keep buses running on the same basis, at least to finish their routes / shifts and clear a possible backlog of riders. I have heard their radio traffic after a snowstorm, buses get frequent radio comms telling them about road conditions ahead on their routes. Its just a variation on the tried and true adapt, improvise and overcome strategy. But it points to a pretty important thing about disasters: there is no secret protocol for how transit operators will react after an uncommon disaster, they will probably react pretty much like they do after common ones. I know of no credible strategy to return all buses to base, passengers be damned. If the buses are blocked by traffic, they're not going anywhere, and you should walk. Most times if the bus is running, it will get you there, eventually. But if the bus driver abandons his bus, something truly weird is underway, you should consider leaving the area too...