Structure 357 · Alpena County, MI
Carries Second Avenue over Thunder Bay River, 0.2 Mi E Of Us23.
Set by its lowest-rated component: Superstructure and Substructure at 5 of 9.
How ratings work264 ft end to end: about 4 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 bascule bridge (drawn closed).
| State | Michigan |
| County | Alpena |
| Location | 0.2 Mi E Of Us23 |
| Carries | Second Avenue |
| Crosses | Thunder Bay River |
| Coordinates | 45.06390, -83.43060 |
| Material | Steel |
| Design | Movable - Bascule |
| Total Length | 264.4 ft (80.6 m) |
| Max Span | 127.0 ft (38.7 m) |
| Deck Width | 62.0 ft (18.9 m) |
| Deck Area | 1523.3 sq m |
| Main Spans | 1 |
| Year Built | 1939 (reconstructed 1988) |
| Avg Daily Traffic | 15,700 (2016) |
| Truck Traffic | 6% |
| Lanes On Bridge | 3 |
| Last Inspection | July 2023 |
| Inspection Frequency | Every 24 months |
| Owner | City/Municipal Highway Agency |
| Historical Significance | Bridge is on the National Register of Historic Places |
| Scour Critical | 4 — Foundations need monitoring |
| Structure Number | 000000000000357 |
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.