Mackinaw Rd over I-75
Bay County, Michigan · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- Mackinaw Rd over I-75 in Bay County, Michigan, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the superstructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1967 and reconstructed in 2019, making it 58 years old at the 2025 inventory.
- It carries about 2,598 vehicles a day (traffic count year 2016).
- Its listed owner is the state highway agency.
- It is one of 93 of the 166 inventoried bridges in Bay County rated fair (56.0%); 27 (16.3%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its class is unchanged from 2024 (fair), but component ratings moved: deck 8 to 7.
- Its most recent inspection on record is dated March 2024, on a 24-month routine inspection cycle.
- A fair rating means the lowest-rated major component scores 5 or 6 on FHWA's 0-9 scale: some deterioration or minor section loss, but the structure is sound. It is the middle class, not a warning.
View this bridge on a map → (43.65138, -83.98995)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 8 | 7 | Good condition |
| Superstructure | 5 | 5 | Fair condition |
| Substructure | 8 | 8 | Very good condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 252 ft |
| Location | 6.5 Mi NW of Bay City |
| NBI structure number | 000000000000633 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | March 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | N: not over a waterway |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Michigan department of transportation.
Busiest bridges in Bay County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-75 NB over Squaconning Creek | 1960 | 57,600 | Fair |
| I-75 SB over Squaconning Creek | 1960 | 57,600 | Fair |
| I-75 NB over Goetz Drain | 2010 | 53,002 | Good |
| I-75 NB over Hesr | 1960 | 44,350 | Poor |
| US-10 EB over Gtw RR | 1961 | 35,800 | Fair |
| US-10 WB over Gtw RR | 1961 | 35,800 | Fair |
All bridges nearby: Bay County, MI bridge conditions · every bridge in Bay County · Michigan bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.