Climate change has caused rising water at the undersized tidal crossing at Old Ferry Road in Wiscasset, Maine. Sustainable, adaptive design is necessary to replace the failing culvert.
The Town has retained Wright-Pierce to design a replacement bridge for the crossing. The replacement bridge will enhance the health and habitat connectivity within the surrounding tidal marsh and allow safe travel for vehicles for a 100-year design life in accordance with MaineDOT standards and with design guidance from the CoastWise Approach for Tidal Road Crossings. The Town plans to turn ownership of the replacement bridge over to MaineDOT at the conclusion of the project.
Repairing the culvert will provide continued access along Old Ferry Road. Several commercial properties, including Central Maine Power and MoInlycke Health, are solely accessible via Old Ferry Road. Additionally, the road services a river landing that is used for recreational activities, worm harvesting, and clam harvesting.
Wright-Pierce conducted field and topographic surveys at the project site to assess the existing conditions and create a base map for study and design phases of the project. The Maine Coastal Program provided tidal monitoring data and supplemental stream cross sections in the project area and Atlantic Environmental, LLC determined wetland regulatory boundaries. Wright-Pierce and Northern Test Boring of Gorham conducted subsurface exploration and sampling for design of foundations to support the replacement bridge.
The preliminary phases of the project included sea-level rise modeling projections; hydrologic analysis; incorporation of field survey into hydraulic modeling and analysis; and replacement bridge sizing analysis. After the study phase, Wright-Pierce completed environmental permitting and preliminary and final design plans in accordance with MaineDOT standards. Final design elements included design of bridge and foundations, temporary access to maintain traffic during construction, approach roadways, and utilities.
The design (images shown below) includes consideration for sea-level rise scenarios over the 75-year design life of the replacement bridge. An adaptive design approach is anticipated to allow the community to meet current needs and prepare for predicted climate changes over the life of the structure with uninterrupted service. Other waterfront communities face these same challenges with aging infrastructure and rising water. Contact us today to learn more about this and other transportation-related projects.
Existing and Proposed Conditions: Design Tide, Seal Level Rise
Existing and Proposed Conditions: Coastal Storm, Seal Level Rise