The Twin Bridges are bridges that span two branches of the Baboosic Brook to provide pedestrian access across an island in Twin Bridge Park. The bridge spanning the southerly branch of the Baboosic Brook is a single concrete arch, while the bridge spanning the northerly branch consisted of two arches. During the May 2006 flood, the north span was heavily damaged. The north abutment of the bridge was severely undermined and the bridge dropped, leaving no reasonable options for repair.

This project was the recipient of FEMA Public Assistance funding. The Town of Merrimack contracted with Quantum Construction Consultants to design a replacement structure. The new structure is a prefabricated steel truss pedestrian bridge that spans approximately 70 feet over the brook to the island.

The new bridge structure is founded on new tall concrete abutments located on the banks, to provide greater waterway clearance and hydraulic capacity.