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I-93 SB over Old Nh 3B

Belknap County, New Hampshire · rated Fair in the 2025 National Bridge Inventory

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

I-93 SB over Old Nh 3B in Belknap County, New Hampshire, is rated in fair condition in the 2025 National Bridge Inventory (as of August 20, 2026).
Its lowest-rated component is the substructure, rated 6 (satisfactory condition) on the 0-9 scale.
It was built in 1962 and reconstructed in 1986, making it 63 years old at the 2025 inventory.
It carries about 14,214 vehicles a day (traffic count year 2023).
Its listed owner is the state highway agency.
It is one of 42 of the 112 inventoried bridges in Belknap County rated fair (37.5%); 5 (4.5%) are rated poor.
A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.

Component ratings


Structure	Steel stringer or multi-beam girder
Length	about 134 ft
Location	Tilton-sanborton Tl
NBI structure number	023101520003900
Condition class	Fair

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

Bridge	Built	Vehicles/day	Condition
US 3 Nh 11 NH132 over I-93	2000	23,105	Good
US 3 Nh 11 NH132 over Gulf Brook	1936	23,105	Fair
I-93 SB over NH104 NH132	1963	19,812	Fair
NH106 Main St over Winnipesaukee River	1970	18,507	Fair
US 3 over Maple St Nhrr	1947	17,943	Good
US 3 Nh 11 over Winnisquam Lake	1973	16,322	Good