Construction of the Seabrook Bridge in Seabrook began in May 2024 and is projected to be completed in October 2028. The project has a budget of $107 million and is almost entirely federally funded, with an additional $2.4 million contributed by municipalities and utility companies.
The project will replace the Neil R. Underwood Bridge, which carries NH 1A (Ocean Boulevard) over the Hampton River at the entrance to Hampton Harbor.
According to a New Hampshire Department of Transportation post, "The project is currently in phase two traffic configuration where off-alignment work for the proposed substructure and superstructure can be completed."
The post also stated, "The new bridge will be a fixed high-level steel girder structure located west of the existing bridge on a horizontally curved alignment. The bridge will span 1,300 feet with seven spans and will feature a wider roadway — 38 feet between curbs, including two 11-foot travel lanes and 8-foot shoulders. It will also incorporate two 6-foot sidewalks with designated overlooks while maintaining the full 150-foot-wide federal navigation channel with a vertical under-clearance of approximately 48 feet. Beyond the bridge itself, the project includes full reconstruction of NH 1A's approach roadways. A pedestrian walkway will also be built beneath the bridge's north span."
SPS New England is the lead contractor on the project. According to an SPS New England post, "We are nearing completion of the deep foundations for the future bridge structure. Construction crews have started work on the substructure concrete for the piers, and the first pier footing was completed with a total concrete volume of 700 cubic yards."
The project has completed all initial gas, water and existing bridge electrical utility relocations. Construction access trestles and cofferdams at Piers 1 and 6 were installed during a strict environmental window between Nov. 15 and March 15. The north and south proposed bridge abutments, using deep H-pile foundations, were installed, and concrete for the footing, stem, and wingwalls was placed prior to pier construction.
Proposed bridge pier drilled shafts and precast tubs were constructed in a raised position to improve worker access.
During the winter, the precast tubs were lowered using hydraulic jacking to their final elevations and filled with concrete to form the footings for Piers 1 through 6. All piers have since been completed, and structural steel has been erected over the navigation channel between Piers 3 and 4. Installation of a 65-ft. CCTV pole foundation also has been completed, along with various drainage improvements.
Remaining work includes erecting the remaining structural steel, installing structural backfill behind both abutment approaches and completing installation of the northwest and northeast sheet pile approach walls with a cast-in-place architectural pattern. Throughout the summer, crews will install precast concrete deck panels on the proposed bridge, followed by the concrete deck, sidewalks and guardrail systems.
Once traffic is shifted to the final alignment, additional work will include removal of the existing bridge deck, structural steel, lift span and mechanical operating equipment. Cofferdams will then be constructed around the existing bridge piers to contain demolition debris from the pier stems and footing material below the existing mudline during the winter of 2026.
All temporary construction access measures will ultimately be removed, and all identified project punch-list items will be completed prior to contractor demobilization in the fall of 2028.
