it was a 300meter+ span and a 10 car train making 4 passes and both directions. there were anchor points at both sides of the rails but that was all. suspeneded designs all over stresses the supports, even with a counterweight of heavy steel. most of my arch desgins faield as well. what i was trying to do was build a bridge anchored on one end with legs to rest on the river bottom to support the central spans without having anchor points. making it fall into place with cables or light steel to get it to go the right driection. the problem i ran into was that the deck rarely lined up enough to allow the train across, and the water level was right at the precipice of the rails.