Thorntons Ferry Rd over Beaver Brook
Hillsborough County, New Hampshire · rated Poor in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Thorntons Ferry Rd over Beaver Brook in Hillsborough County, New Hampshire, is rated in poor condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the culvert, rated 1 (imminent failure condition) on the 0-9 scale.
- It was built in 1970, making it 55 years old at the 2025 inventory.
- It carries about 356 vehicles a day (traffic count year 2023).
- Its listed owner is a city or municipal highway agency.
- It is one of 31 of the 385 inventoried bridges in Hillsborough County rated poor (8.1%); 31 (8.1%) are rated poor.
- Its traffic status in the 2025 inventory is open, temporary structure in place to carry legal loads while the original structure is closed awaiting replacement or rehabilitation (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated June 2024, on a 16-month routine inspection cycle.
- 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 → (42.85892, -71.61628)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Culvert | 1 | 1 | Imminent failure condition |
Bridge details
| Structure | Steel culvert |
| Length | about 20 ft |
| Location | 3.2 Mi Fr Merrimack Tl |
| NBI structure number | 000701450010600 |
| Condition class | Poor |
| Traffic status (item 41) | Open, temporary structure in place to carry legal loads while the original structure is closed awaiting replacement or rehabilitation |
| Last inspection (item 90) | June 2024 |
| Inspection interval (item 91) | 16 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the New Hampshire department of transportation.
Busiest bridges in Hillsborough County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Fee Tpk N&S Ramps over Salmon Brook | 1955 | 128,889 | Good |
| Fee Tpk over Greeley Street | 1993 | 78,063 | Good |
| Fee Tpk over Souhegan River | 1953 | 75,081 | Good |
| Fee Tpk over Baboosic Brook | 1954 | 75,081 | Good |
| US 3 Fee Tpk NB over Nashua River | 1955 | 73,979 | Fair |
| US 3 Fee Tpk SB over Nashua River | 1959 | 71,221 | Good |
All bridges nearby: Hillsborough County, NH bridge conditions · every bridge in Hillsborough County · New Hampshire bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.