GZA provided professional engineering services to the Design/Build team for the MassDOT Whittier Bridge/I-95 Improvement Project.


This project included the replacement and widening of the Whittier Bridge over the Merrimack River, widening the I-95 roadway between Newburyport and Salisbury, improving several I-95 exit ramps, and upgrading drainage and lighting systems. In addition to being one of the busiest roadways in North America, challenges for the widening of the bridge included lack of overburden soils/high bedrock profile, the proposed construction sequence and limited work area.


In support of the Design/Build team, GZA provided geostructural design services for the temporary works. Our team designed temporary cofferdams for construction of Whittier Bridge piers that consist of braced steel sheeting with tremie plugs. GZA also designed precast walls for bridge piers under various construction phase loading which are used to support the exterior granite finish as well as serve for temporary cofferdam during construction and form work during pier cap concrete pour. GZA provided support of excavations (SOE) at the Whittier Bridge abutments and the Pine Hill, Railroad Bridge and Route 110 approach bridges consisting of driven piles and/or drilled micropiles with multiple level of tiebacks. The SOE was coordinated to comply with the phased construction and traffic plans. GZA provided geostructural design assistance for retaining walls along the project alignment and designed temporary and permanent soil nail walls in order to facilitate the proposed MSE wall construction for widening roadway. GZA also provided static micropile tests and dynamic pile testing. GZA designed the load test frames for static load tests on the bridge pier micropiles and observed the tests and performed dynamic pile testing (PDA) for the abutment piles.


The design needed to consider various construction loading, scheduling, as well as river current and ice impact.