On our walk from the library to the arena where they were holding the circus, we crossed a bridge which is located right above some train tracks. I'm rather glad the train wasn't passing by. I'm sure it's speed would transfer some motion to the bridge. You don't see many trains go by very much, though I think many travel by in the early mornings to avoid clogging up traffic during the day. Waiting on a train can be a pain when it never seems to end.