Structure 15301090013400 · Grafton County, NH
Carries Nh 18 over Connecticut River, Nh-vt Sl.
Set by its lowest-rated component: Superstructure and Substructure at 4 of 9.
How ratings work533 ft end to end, longest span 138 ft: about 7 semi-trucks nose to tail. Lengths and the semi-truck on the deck are drawn to the same scale. Each part is colored by its latest inspection rating. The inventory records lengths but not heights or the layout of the shorter spans, so those are drawn as typical for a girder bridge.
| State | New Hampshire |
| County | Grafton |
| Location | Nh-vt Sl |
| Carries | Nh 18 |
| Crosses | Connecticut River |
| Coordinates | 44.34264, -71.88890 |
| Material | Steel |
| Design | Girder and Floorbeam |
| Total Length | 533.1 ft (162.5 m) |
| Max Span | 138.1 ft (42.1 m) |
| Deck Width | 30.5 ft (9.3 m) |
| Deck Area | 1511.2 sq m |
| Main Spans | 5 |
| Year Built | 1934 (reconstructed 1980) |
| Avg Daily Traffic | 1,508 (2023) |
| Truck Traffic | 4% |
| Lanes On Bridge | 2 |
| Last Inspection | November 2024 |
| Inspection Frequency | Every 8 months |
| Owner | State Highway Agency |
| Historical Significance | Bridge is possibly eligible (requires evaluation) |
| Scour Critical | 7 — Countermeasures installed |
| Structure Number | 015301090013400 |
Inspectors rate each major part of a bridge (the deck you drive on, the superstructure of beams that holds it up, and the substructure of piers and abutments beneath) on a 0–9 scale. A bridge's overall condition is its lowest of those ratings, so one deteriorated component makes the whole bridge "poor."
A poor rating is not a closure. It means the bridge is flagged for priority repair or replacement; bridges judged unsafe are closed or posted with weight limits. The waterway (channel) rating is reported, but it does not count toward the overall classification.