9th Street Bridge

American Bridge held a subcontract from Schiavone Construction Company for the fabrication and erection of the superstructure for this miniature, high quality vertical lift bridge, including the supply and installation of all operating machinery. The bridge replaces a bascule structure that was removed under Schiavone’s contract. This structure has a vertical lift span girder 80′ long and 47′ wide and lifts to provide an 82′ vertical clearance. The bridge was erected underneath an active New York City Transit elevated rail line. This structure’s columns were fitted with jacking devices to allow adjustment in the event of any settlement or lateral movement during the construction of the foundations for the new vertical lift bridge. The movement of the existing structure was carefully monitored, and jacking occurred in a planned, organized sequence when required. In view of the space restrictions, American Bridge designed a gantry that was cantilevered from the tower top for erection of the 24 ton sheaves. The sheaves were hoisted using hoisting engines, then slid to their final position on Hillman Rollers. The new liftspan is operated by two sets of two 30hp electric motors, one in each tower top. The machinery is synchronized using electronic skew controls. The main differential reducer can be driven by either of the two motors in each tower top, with the other motor serving as backup. Redundant electrical systems allow the bridge to be run under PLC controls or handwired backup systems. A natural gas fired generator provides backup power. The bridge was erected in the up position to allow navigation to continue through construction. Air motors allowed for operation of the span when necessary during construction. American Bridge self?performed all structural steel erection, jacking of the existing transit structure, installation of steel grid floor system and operating equipment installation.