The previous bridge with its 20 steel girders and concrete deck had carried traffic on US Route 1 over Interstate 95 since 1958. Linking New York City and Boston, I-95 is the most congested roadway in Connecticut, especially so in the Stamford-to-New Haven corridor where 140,000 vehicles travel the road every day. Given the heavy traffic count and the density of the local population and businesses, along with important teaming, technology, environmental, and location considerations, Accelerated Bridge Construction (ABC) was deemed the best method for replacing the bridge. O&G completely pre-built the two replacement spans alongside Bridge #00037 which proceeded according to plan and schedule. Each pre-built span consisted of constructing ten (10) steel plate girders with cross-frame diaphragms and an 8-1/2” thick cast-in-place concrete deck with sidewalks and parapets. The pre-built spans were approximately 70’ wide by 120’ long and were constructed above ground on temporary steel shoring towers and steel support beams, which simulated the permanent abutment and bridge seats. Because of detailed pre-planning and cooperation among all parties, bridge demolition and replacement on two, back-to-back weekends occurred without complications. Traffic was restored a full day ahead of schedule each weekend, with minimal disruption to the motoring public.
The stakes for success on this project were very high. Any failure on the weekends of demolition and replacement, when traffic would be at its peak and media coverage would be intense, would have a major negative impact on traffic throughout southwestern Connecticut and reflect terribly on the entire team’s competency. The project team’s careful planning, from calculating grades of the temporary access road that the Self-Propelled Modular Transporters (SPMT) would travel to avoid unnecessary strain on the bridge structure, to coordination with local & state police and emergency personnel, to scheduling crews for the around-the-clock operations, to updating the DOT and media of all detours allowed for the weekend operations to not only finish on time, but a full 24-hours early each weekend.
ABC was the clear choice for many reasons: improved quality of the delivered product, road closures confined to just the two weekends when the bridge would be replaced, improved safety for motorists and particularly for the crews building the bridge, quicker delivery time, and cost savings over conventional bridge construction. This successful project was completed nearly two months ahead of the contractually scheduled date.
