ADOT Places Largest Girders in State on Salt River Bridges Construction Equipment Guide » As long as a 17-story building and each weighing as much as 14 elephants, 94 extra-long single span girders have been placed on two bridge structures in Arizona over the Salt River when the South Mountain Freeway opens by late 2019. Michelle2017-09-14T14:19:16-08:00September 12th, 2017|Arizona, Bridges, Highways|