M-99 M-50 over Mill Race
Eaton County, Michigan · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- M-99 M-50 over Mill Race in Eaton County, Michigan, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the substructure, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1995, making it 30 years old at the 2025 inventory.
- It carries about 15,977 vehicles a day (traffic count year 2007).
- Its listed owner is the state highway agency.
- It is one of 128 of the 202 inventoried bridges in Eaton County rated fair (63.4%); 11 (5.4%) are rated poor.
- Its traffic status in the 2025 inventory is open, no restriction (NBI item 41).
- Its condition class and component ratings are unchanged from the 2024 inventory.
- Its most recent inspection on record is dated May 2023, 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 → (42.50903, -84.65596)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 7 | 7 | Good condition |
| Superstructure | 6 | 6 | Satisfactory condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Prestressed concrete single box beam |
| Length | about 38 ft |
| Location | S of State St |
| NBI structure number | 000000000002299 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | May 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 5: foundations stable, scour within the limits of the footing or piles |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Michigan department of transportation.
Busiest bridges in Eaton County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| I-96 WB over Grand Riv & Billwood Hwy | 2023 | 47,900 | Good |
| I-96 EB over M-43 | 1962 | 31,250 | Fair |
| I-96 WB over M-43 | 1962 | 31,250 | Fair |
| Otto Road over I-69 | 1989 | 27,800 | Fair |
| I-96 EB over Grand River | 1962 | 27,100 | Fair |
| I-96 WB over Grand River | 1962 | 27,100 | Fair |
All bridges nearby: Eaton County, MI bridge conditions · every bridge in Eaton County · Michigan bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.