Saint Louis Bay Bridge

A 10,170-ft-long railroad bridge across a shallow bay consists of 60-ft prestressed, precast concrete box girders supported on prestressed concrete cylinder piles and a 285-ft-long structural steel truss swing span. All of the concrete components except the end abutments, pivot pier and rest piers were precast in an existing plant, barged to the site installed. The 500-ton steel swing span was assembled on barges. Towed to the site and lifted by the three cranes onto the pivot and rest piers. Driving 54-in. cylinder piles through heavy clay required pre-boring a hole with a special jetting apparatus. The bridge was designed for E-80 railroad loading and to withstand hurricane wave loadings estimated for a 100-year storm. Two years after completion, Hurricane Camille battered the bridge with much greater forces than those assumed, resulting in considerable damage but not destruction of the structure.