M-66 over Manistee River
Kalkaska County, Michigan · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- M-66 over Manistee River in Kalkaska County, Michigan, is rated in fair condition in the 2025 National Bridge Inventory (as of ).
- Its lowest-rated component is the deck, rated 5 (fair condition) on the 0-9 scale.
- It was built in 1979, making it 46 years old at the 2025 inventory.
- It carries about 1,150 vehicles a day (traffic count year 2019).
- Its listed owner is the state highway agency.
- It is one of 7 of the 15 inventoried bridges in Kalkaska County rated fair (46.7%); 1 (6.7%) 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 June 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 → (44.52372, -85.17189)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 5 | 5 | Fair condition |
| Superstructure | 5 | 5 | Fair condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Prestressed concrete stringer or multi-beam girder |
| Length | about 159 ft |
| Location | 1.1MI N of Missaukee Col |
| NBI structure number | 000000000004696 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | June 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 Kalkaska County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Us-131|m-66|m-72|s over N Br Boardman River | 1940 | 8,567 | Fair |
| N Rapid City Road over Rapid River | 1983 | 5,800 | Good |
| Boardman Road over Boardman River | 1988 | 1,700 | Fair |
| Aarwood Road over Rapid River | 2012 | 1,340 | Good |
| W Sharon Road over Manistee River | 1958 | 1,060 | Good |
| N Sharon Road over Manistee River | 1971 | 330 | Fair |
All bridges nearby: Kalkaska County, MI bridge conditions · every bridge in Kalkaska County · Michigan bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.