I-93 Rapid Bridge Replacement
- Jun 7, 2013
Accelerated Bridge Construction
From June to August 2011, Interstate 93 (I-93) in Medford, Massachusetts, was the stage of a carefully orchestrated Massachusetts Department of Transportation (MassDOT) bridge replacement project, using accelerated bridge techniques. Fourteen bridges, consisting of the northbound and southbound structures at seven different crossings of the interstate, were be replaced over the course of the 2011 summer weekends. Using conventional construction methods, it would have taken at least four years to replace all fourteen bridges.
Branded as the I-93 Fast14 Project, MassDOT used design/build procurement, a prefabricated bridge elements system, and a special rapid-setting concrete to minimize disruption to the traveling public. The bridges were replaced with modular superstructure units fabricated off-site using steel beams and epoxy-coated reinforcing steel. A total of 252 precast modular components were used in this project.
The modular units were fabricated in a factory and these were installed by crane, replacing at least one bridge each weekend.
Original Bridge Construction
The original bridges had been built almost 60 years ago and had reached the end of their service lives, with concrete decks and the superstructures in poor condition. The piers and abutments for the structures were generally in good condition. In 1997, average traffic volumes were in excess of 100,000 vehicles per day in Salem, with segments between interchanges two and five carrying up to 80,000 vehicles per day.
With less than twelve months separating project inception to the first bridge’s replacement, the audacious scope and schedule of the Fast14 set a new standard against which future endeavors of this vein can be judged.