US 4 over Smith River
Merrimack County, New Hampshire · rated Poor in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- US 4 over Smith River in Merrimack County, New Hampshire, is rated in poor condition in the 2025 National Bridge Inventory (as of ).
- It was built in 1929 and reconstructed in 1991, making it 96 years old at the 2025 inventory.
- It carries about 2,087 vehicles a day (traffic count year 2023).
- Its listed owner is the state highway agency.
- A poor rating means at least one major component - deck, superstructure, or substructure - is rated 4 or lower on FHWA's 0-9 scale. It does not by itself mean the bridge is unsafe; bridges judged unsafe are closed or load-restricted by their owners.
View this bridge on a map → (43.5299, -71.86989)
Component ratings
| Component | Rating (2025) | FHWA scale meaning |
|---|---|---|
| Deck | 6 | Satisfactory condition |
| Superstructure | 4 | Poor condition |
| Substructure | 4 | Poor condition |
Bridge details
| Structure | Steel girder and floorbeam |
| Length | about 69 ft |
| Location | 4.6 Mi From Wilmot Tl |
| NBI structure number | 005801380009400 |
Source: FHWA National Bridge Inventory, 2025 data as reported by the New Hampshire department of transportation.
All bridges nearby: Merrimack County, NH bridge conditions · New Hampshire bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.