DOT unveils Mile Hill Road bridge rehab, plans nine-month construction window in 2027

The New Hampshire Department of Transportation on Tuesday presented a preliminary plan to rehabilitate the bridge carrying US 3/NH 11 over Mile Hill Road, telling the Laconia City Council the 1967 single-span structure requires significant work on its deck and superstructure.

"My name is John Stockton. I am the in house design chief for New Hampshire DOT for the Bureau of Bridge Design," said John Stockton, who opened the presentation and introduced consultant engineers from McFarland Johnson.

Consultant Sam White said inspections show the bridge’s deck and superstructure are rated condition state 5 on the National Bridge Inspection Standards scale — a fair condition that places the structure near the state’s red list. He said the project’s purpose is "to address the structural deficiencies of the bridge and maintain that safe working transportation system."

Engineers presented three alternatives: a deck replacement that retains existing concrete beams, a recommended superstructure replacement using new steel beams and a new deck, and a full replacement examined as a cost benchmark. White said the superstructure replacement most directly addresses concerns about long-term strength and makes it easier to increase vertical clearance.

Construction sequencing will require temporary traffic controls on US 3/NH 11 and reductions to a single lane on Mile Hill Road for safety. "That condition would last the life of the project mostly, which is about 9 months," White said, adding that traffic can be staged so buses will continue to pass and that signal control or stop-sign control is being evaluated for the work zone.

The project is listed in the state’s 10-year plan and will be funded with federal and state dollars; consultants said municipal agreements with the city will be developed as design advances. Stockton said preliminary design is ongoing, final design is planned for September, the project will be advertised in October and construction is expected to start in 2027.

Council members asked about bus access, temporary signaling and substructure work; consultants said the superstructure option facilitates raising beam depth to meet the state’s desired vertical clearance and that abutment seats and back walls will be modified to accommodate larger bearings and a more durable joint system.

The DOT team invited local input through the NEPA consultation process and said they did not identify environmental or historical-resource constraints that would require additional permits.