H&H provided transportation engineering design services for the replacement of twin bridges on I-75 over SR 50. The 298.5-foot simple span fixed bridges are the longest bridges of their kind in the southeastern region and carry both north and southbound I-75 traffic over the SR 50 single-point urban interchange.
The approximately 12-foot superstructure consists of weathering steel plate girder structures supported on end bents. Mechanically-stabilized earth walls wrap around each bridge, which continues for hundreds of feet before meeting at grade. The massive girders have been innovatively constructed using the existing piers as temporary shoring towers.
The project also included a temporary widening of the existing southbound I-75 bridge as part of the maintenance of traffic plan during the new bridge’s construction. The interchange design can be described as a “single-point diamond,” which added multiple exit lanes for left and right-hand turns onto SR 50 and offers more efficient signal operations.