The Norwalk rail accident occurred on May 6, 1853, in Norwalk, Connecticut, and was the first major U.S. railroad bridge disaster; 48 were killed when a train travelling at 50 mph plunged into the Norwalk Harbor off of an open draw (swing) bridge. The accident occurred on the New York and New Haven Railroad where it crosses a small inlet of Long Island Sound via a swing bridge. The approach from New York is around a sharp curve, so there was a signal indicating if the bridge was passable by trains: a red ball mounted upon a tall pole.