MD 17

This existing bridge experienced a gradual 1” drop in elevation due to section loss in the rocker bearings at the exterior supports, which became disruptive and hazardous for traffic.  ALA designed the jacking scheme to replace the defective bearings and restore a level deck surface while maintaining both existing traffic lanes open.  The design of the girder extension and the jacking assembly was optimized to fit in the tight space between adjacent spans and to minimize deflection from live load. Because each girder has to be raised over 1”, simultaneous jacking of both girders was specified to minimize stresses from racking effects.