NH DOT proposes $17 million Route 101 overhaul, including Branch River bridge replacement

New Hampshire Department of Transportation staff on Feb. 12 presented a federally funded plan to rehabilitate about 1.10 miles of Route 101 east of Opti Labs, replace the deteriorated Branch River bridge and add 5‑foot shoulders and intersection improvements, officials said.

Dave Smith, a New Hampshire DOT project lead, told the Swansea Select Board the project runs from near Marlborough/Marble Street east past Branch Road and includes work at the Swansea Factory Road and Branch Road intersections. “We want to come for you tonight just to give a presentation for our project load 1 0 1,” Smith said.

The nut of the project is pavement rehabilitation and safety upgrades: designers will remove a roughly 20‑foot‑wide concrete slab under the pavement, provide formal 5‑foot shoulders on both sides while maintaining 12‑foot travel lanes, correct drainage and stormwater treatment, and replace the Branch River bridge, which staff identified as being on the state’s “red list.” The preliminary construction estimate presented to the board was about $17,000,000.

Ellen Mosher, project manager for CHA (the DOT’s design consultant), said nondestructive testing of the existing Branch River structure found alkali‑silica reaction in concrete cores — a form of deterioration sometimes described as “concrete cancer” — and that the team is proposing full replacement rather than rehabilitation. “We determined that the concrete is sound out there. However, we saw some areas of deterioration ... the results came back that the bridge has alkali silica reaction,” Mosher said.

The design team said it evaluated five alignment concepts for the Swansea Factory Road area and, following public and working‑group input, favors an alternative (referred to as 2c in the presentation) that realigns Swansea Factory Road behind a fastener mill, moves the roadway away from the river and includes a future roundabout to improve traffic control. The plan would discontinue the existing Swansea Factory Road alignment where the roundabout is proposed.

Mosher and Smith emphasized corridor constraints created by the Branch River and adjacent private properties, noting the design aims to minimize slope and resource impacts while delivering the shoulders and lane geometry. “One of the things that’s unique about this project is really the constraints along the corridor due to the proximity of the Branch River and also the private properties along the corridor,” Mosher said.

The team walked the board through property impacts. Smith said Jay Blanchard’s building sits within state right of way and is “very much impacted” by the proposed roundabout; staff described a conceptual plan to lift and relocate Blanchard’s building within his lot if negotiated. The presentation also noted small commercial buildings near the Moose Mart that fall into the proposed right of way and may require acquisition; staff said discussions with property owners are ongoing.

Environmental and cultural reviews are underway. Mosher said summer acoustic bat surveys recorded two species, including the northern long‑eared bat and the tricolored bat, and that timing restrictions for tree clearing will be required during construction. Architectural surveys flagged several potentially historic buildings and noted the stone arch bridge in the area is listed on the National Register; the Branch River bridge is eligible for listing. The team also reported limited archaeological work and ground‑penetrating radar that identified buried remains in one area tied to former mill uses, requiring monitoring during construction.

Schedule and approvals: the team is preparing a draft NEPA document and expects a public hearing this summer as a key milestone before final design. Mosher said right‑of‑way plans and negotiations with affected owners would follow, with final (file) design work targeted in 2026–2027 and construction beginning in spring 2027, spanning roughly 2½ construction seasons. Smith estimated the corridor carries about 12,000 vehicles per day.

Traffic management during construction will vary by phase; the presenters said one lane of traffic can be maintained at times, with alternating traffic possible under temporary control, and limited detours via Branch Road or regional side streets as needed. The team acknowledged the capacity limitations of nearby detour routes.

Why it matters: replacing a red‑listed bridge, addressing structural concrete deterioration, and formalizing shoulders and left‑turn treatment will change operations and property access on a well‑traveled segment of Route 101. Staff said they will continue property‑level outreach and expect negotiated right‑of‑way impacts and compensation where needed.

The board received the presentation and asked questions about sight distance, truck restrictions and how Swansea Factory Road traffic could change with the proposed roundabout; DOT staff noted a truck restriction exists on parts of Swansea Factory Road and said modeling shows the roundabout would operate under a range of demand scenarios.

Next steps: the DOT/CHA team will finalize environmental studies, advance NEPA, seek consulting‑party participation, hold a public hearing this summer, produce final right‑of‑way plans and continue individual property negotiations ahead of the 2026–27 final design and the targeted 2027 construction start.