I-87 Twin Bridges Deck Replacement (Thaddeus Kosciuszko Bridge) over the Mohawk River
Challenges Answered With A Precast Concrete Solution
The deck replacement and steel rehabilitation of the I-87 Bridges (north bound and south bound bridges) over the Mohawk River had many challenges. The greatest challenge was to complete the rehabilitation without significantly impacting the 110,000 vehicles per day using this critical corridor.
This project was a part of both "The NY Works Program" and "Drivers First Initiative." The importance of this project warranted the NYSDOT to utilize a new contracting method called “Best Value”. This process allowed NYSDOT to pre-qualify contractors to participate in the bidding process. Lane Construction was ultimately selected to perform the work and completed the project in just 12 week-end closures with minimal impact to the traveling public.
There are 224 precast bridge units and 12 precast approach slabs incorporated into the project. The traffic barrier was cast monolithically with the fascia units. The Fort Miller Co., Inc. developed a high performance lightweight concrete mix design in accordance with the guidelines set forth by NYSDOT. (The lightweight concrete mix design achieved release strengths of 4000 psi within 18 hours with an average 28-day strength in excess of 7000 psi. The specified lightweight concrete equilibrium density was 115 pounds per cubic foot.)
The lightweight precast concrete pieces had a 26% reduction in weight per piece that in turn assisted with the sizing of the mobile crane. High-performance rapid set concrete was used at the closure pours between the precast elements making the deck and barrier continuous and joint-free. Upon completion, the deck was topped with an asphalt overlay.
Structural Precast Elements:
• 12 precast approach slabs