Bridge conditions in Merrimack County, New Hampshire
326 inventoried bridges · 27 rated poor · 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
The federal inventory lists 326 bridges in Merrimack County: 146 rated good, 153 fair, and 27 poor.
- 27 of the 326 bridges in Merrimack County, New Hampshire, are rated in poor condition (8.3%) in the 2025 National Bridge Inventory, as of .
- 146 bridges (44.8%) are rated good and 153 (46.9%) fair.
- The median Merrimack County bridge was built in 1966.
- The busiest poor-rated bridge is I-89 over South Street (built 1959), carrying about 46,612 vehicles a day.
Good 44.8% · Fair 46.9% · Poor 8.3% of 326 bridges
Bridges rated poor
Every bridge in the county with a poor rating, busiest first. Poor means a major component is rated 4 or lower on FHWA's 0-9 scale; it is a repair flag, not a closure notice.
Busiest bridges in the county
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-93 Fee Tpk Ramp over Hackett Hill Road | 1978 | 86,013 | Fair |
| I-93 Fee Tpk over Cross Road | 1956 | 82,029 | Fair |
| I-93 Fee Tpk over Ramp A-b | 1957 | 79,640 | Fair |
| I-93 Fee Tpk over Dow Road | 1957 | 78,501 | Fair |
| I-93 Fee Tpk over Robinson Road | 1957 | 78,501 | Fair |
| I-93 Fee Tpk over US 3 Manchester Street | 2000 | 75,054 | Good |
| I-93 Fee Tpk over Nh 9 Loudon Road | 1966 | 72,557 | Fair |
| I-89 over South Street | 1959 | 46,612 | Poor |
| US202 over Nhrr Constitution Av. | 1958 | 45,555 | Poor |
| US202 over CSX | 1949 | 45,555 | Fair |
Source: FHWA National Bridge Inventory, 2025. Counts cover inventoried highway bridges over 20 feet; ratings are reported by the state DOT.
Every bridge in Merrimack County → - all 326, busiest first, each with its own condition record.
All of New Hampshire: New Hampshire bridge conditions by county · every download on the data page.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.