I remember the flooded subways in the summer of...2000, was it? It was a typical partly sunny summer morning and I was just heading out the door to take the subway to work. A brief thunderstorm dumped a ton of rain on us, but it didn't seem extraordinary at the time. The heavy rain only lasted 15 or so minutes, as I recall, but it made a total mess of the Manhattan subway system that morning. Shut down all the lines that I might have used to go to work. Took me 3 hours to get to work (in hindsight, I could've just walked straight to work in an hour. <img src="/images/graemlins/frown.gif" alt="" /> ). Now, if the power also went out and snarled surface traffic, like buses, during that rush hour? Whew, forgeddaboutit!

Anyway, so if even 15 minutes of heavy rain can paralyze much of the subway system, think what hours or even days of heavy rain can do. I have read that there are pumps in the subway system operating continuously, since even under dry conditions, millions of gallons of water seeps into the sytem daily, but I doubt that they have much excess capacity. I don't think that flood water could ever rise fast enough to actually trap and drown riders in the tunnels before they could be evacuated, but the system can certainly be knocked out of commision very quickly by water.