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Lyman Road over Mill Brook

Grafton County, New Hampshire · rated Good in the 2025 National Bridge Inventory

United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled August 20, 2026

Lyman Road over Mill Brook in Grafton County, New Hampshire, is rated in good condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the deck, rated 7 (good condition) on the 0-9 scale.
It was built in 1926 and reconstructed in 1983, making it 99 years old at the 2025 inventory.
It carries about 573 vehicles a day (traffic count year 2023).
Its listed owner is the state highway agency.
It is one of 262 of the 547 inventoried bridges in Grafton County rated good (47.9%); 43 (7.9%) are rated poor.
A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.

Component ratings

Source: FHWA National Bridge Inventory, 2025 data as reported by the New Hampshire department of transportation.

Bridge	Built	Vehicles/day	Condition
I-89 NB over Plaza Connector Road	2012	28,690	Fair
I-89 Nh 10 over Brook Atv Trail	1959	25,062	Fair
I-89 Nh 10 NB over Truck Road Mascoma River	1966	23,084	Fair
I-89 NB over US 4 Nh 10	1966	22,727	Good
I-89 NB over Connecticut River Necrr	1966	22,288	Poor
I-89 Nh 10 SB over US 4	1966	21,937	Good