Prefab Concrete in Twing Brddge; Easy as ABC

Accelerated bridge construction (ABC) was the method chosen by SEMA Construction to replace the 50-year old Seagoville Road twin-bridges over I-635 in Dallas to minimize the impacts on traffic using the busy highway.

SEMA Construction Inc. crews demolished the existing northbound bridge and replaced it with a new span on the weekend of Aug. 28 to 31, and then repeated the same process for the existing southbound bridge. Both bridges were 219 ft. long and had four lanes.The project began last May and crews are expected to leave the job site in late September, following the clean up and punch list items.

The new bridges are the same length as the originals (219 ft. long) – 105 ft. long for middle pieces and 57 ft. long for pieces on both ends, and 70 ft. wide.The $9.21 million project has been in planning for several years.Each bridge consists of 15 prefabricated concrete pieces: 250,000 lbs., including guard rails. SEMA established five fabrication yards to form the pieces, alongside and parallel to the existing bridges so that they could be rapidly placed.

Equipment

Cranes were critical to the success of the project and a Liebherr LR 1400 lattice boom and Demag CC2500 were utilized to lift and place the prefabricated pieces into place.