Throgs Neck Bridge New Fender System Design-Build

MTA Construction & Development

The Throgs Neck Bridge is an important regional connector for New York City and Long Island, traveled by over 100,000 vehicles per day. To extend the service life of this crossing, MTA C&D is undertaking a design-build project to replace the existing steel truss and timber fenders protecting the bridge’s two towers with a new concrete fender system that meets current standards. The project additionally includes cleaning and painting of tower interiors and various other improvements. 

EnTech is leading the geotechnical instrumentation and monitoring program as a member of the design-build team. The firm began work by conducting a preconstruction survey of the tower’s concrete pedestals and lower-level steel structures. The team developed an instrumentation and monitoring plan to measure vibrations and settlement of the tower pedestals and steel structures during pile driving and other vibration-causing construction activities.  Following approval of the plan, the firm installed vibration monitoring units near each tower, including a 3-component seismograph. EnTech is currently monitoring vibrations during construction and evaluating settlement.