The I-20/59 Bridge replacement over McFarland Blvd in Tuscaloosa, AL consists of a suspended arch bridge with composite steel box girders and trapezoidal steel arches spanning 250 feet. 26 steel cables suspended from the arch support the steel box and concrete deck superstructure with partial depth steel plate floor beams. To allow for I-20/59 to remain open during construction, the bridge is being built in three phases. The steel box girders will temporarily be supported by an intermediate bent creating a two span continuous condition of 125 ft spans allowing for traffic to remain open during various stages of construction. Following the completion of the arch erection and hanger cable installation, jacks at the temporary bent will be lowered to transfer load to the arches.
As a subcontractor to Brasfield & Gorrie, FINLEY Engineering Group (FINLEY) was responsible for Construction Engineering, Temporary In-Service 2 Span Bridge Verification, Temporary Arch Support Tower Design, Temporary Intermediate Bent Design, Erection and Rigging Design, 3-D Erection Manual, Demolition Engineering, and Steel Box Girder and Arch Camber Verification.
FINLEY was also responsible for the development of a unique arch erection sequence per Brasfield & Gorrie’s means and methods to utilize hold cranes and strong backs, thus eliminating the need for arch temporary towers. This revised sequence maintains arch geometry while streamlining and decreasing the erection time by allowing for a majority of the arch complete joint penetration field welded splices to be completed on the ground.