M-32 over S Br Thunder Bay River
Alpena County, Michigan · rated Good in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- M-32 over S Br Thunder Bay River in Alpena County, Michigan, is rated in good condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 7 (good condition) on the 0-9 scale.
- It was built in 1932 and reconstructed in 2009, making it 93 years old at the 2025 inventory.
- It carries about 4,144 vehicles a day (traffic count year 2006).
- Its listed owner is the state highway agency.
- It is one of 11 of the 32 inventoried bridges in Alpena County rated good (34.4%); 2 (6.2%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its class is unchanged from 2024 (good), but component ratings moved: superstructure 8 to 7, deck 7 to 8.
- Its most recent inspection on record is dated July 2024, on a 24-month routine inspection cycle.
- A good rating means every major component - deck, superstructure, substructure, or culvert - is rated 7 or higher on FHWA's 0-9 scale: no more than minor problems.
View this bridge on a map → (45.05911, -83.78205)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 8 | Very good condition |
| Superstructure | 8 | 7 | Good condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Prestressed concrete stringer or multi-beam girder |
| Length | about 49 ft |
| Location | 4.7 Mi E Montmorency Col |
| NBI structure number | 000000000000328 |
| Condition class | Good |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | July 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 7: scour countermeasures installed |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Michigan department of transportation.
Busiest bridges in Alpena County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| US-23 over Thunder Bay River | 1932 | 16,200 | Fair |
| Second Avenue over Thunder Bay River | 1939 | 15,700 | Fair |
| Bagley Street over Thunder Bay River | 2021 | 15,000 | Good |
| US-23 over S Br Devil River | 1936 | 5,537 | Fair |
| US-23 over N Br Devil River | 1933 | 5,537 | Fair |
| M-32 over Bean Creek | 1934 | 5,505 | Fair |
All bridges nearby: Alpena County, MI bridge conditions · every bridge in Alpena County · Michigan bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.