Bridge and Causeway Alternatives Analysis
Goulart Memorial Bridge is part of a 1/2-mile-long stone causeway that serves as the sole access between West Island and the mainland. The bridge spans 27.5-feet over Nasketucket Bay Inlet and consists of prestressed butted voided slabs built in 1970. The bridge was constructed on concrete cap beam abutments, which in turn were placed on stone masonry from the original causeway built in 1920.
Tighe & Bond performed a condition assessment, geotechnical evaluations, and an alternatives analysis to evaluate the bridge and causeway. Our investigations revealed various structural deficiencies with the bridge and were compared against inspection findings from the Massachusetts Department of Transportation (MassDOT). Short-term considerations include rehabilitation or localized replacement of deteriorated structural components of the bridge and the addition of a highway guardrail, which is currently not present along the causeway. We also considered long-term concerns, including managing settlement of the causeway, climate change, and potential sea level rise for coastal resiliency. Long-term solutions evaluated include replacement of the causeway in-kind or with a long-span bridge to connect West Island to the mainland.
Tighe & Bond has considered life cycle costs and remaining service life of the structures. A significant project challenge involves maintenance of traffic throughout construction. Our recommendations report detailed next steps for further engineering and repairs for the Town to proactively budget in their capital improvements plan.
This proactive approach will allow the Town to appropriately budget enhancements to the structure to improve coastal resiliency and to maintain a critical connection to West Island.