I was heavly involved in a bridge collapse on I-5 in central CA back in the 90's. Very light traffic since the freeway had been closed several hours prior thanks to another water related problem. One vehicle containing four people was on the bridge when it went down, they smashed head-on into the far embankment, then the vehicle fell upside down into the water. Four other vehicles went in, and only one driver got out, clinging to a tree in the middle of the water 'til the fire department got there with enough rope to pull him to safety. Five vehicles, eight people, one lived. Lousy odds...