M-18|lake St over S Br Au Sable River
Roscommon County, Michigan · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- M-18|lake St over S Br Au Sable River in Roscommon 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 1935 and reconstructed in 1995, making it 90 years old at the 2025 inventory.
- It carries about 5,505 vehicles a day (traffic count year 2018).
- Its listed owner is the state highway agency.
- It is one of 34 of the 42 inventoried bridges in Roscommon County rated fair (81.0%); 0 (0.0%) 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 → (44.50106, -84.58963)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 5 | 5 | Fair condition |
| Superstructure | 7 | 7 | Good condition |
| Substructure | 5 | 5 | Fair condition |
Bridge details
| Structure | Prestressed concrete single box beam |
| Length | about 49 ft |
| Location | E Lts of Roscommon |
| NBI structure number | 000000000009015 |
| 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) | 7: scour countermeasures installed |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Michigan department of transportation.
Busiest bridges in Roscommon County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| M-18|m-55|w Hought over Denton Creek | 1959 | 11,420 | Fair |
| County Rd 100|SUNS over I-75 SB | 1971 | 9,280 | Fair |
| County Rd 100|SUNS over I-75 NB | 1971 | 9,280 | Fair |
| M-55 EB Ramp over I-75 NB | 1971 | 7,828 | Fair |
| M-55 WB over I-75 NB | 1971 | 7,828 | Fair |
| I-75 Sb|m-55 EB over Old 76|S Saint Helen Rd | 1971 | 7,800 | Fair |
All bridges nearby: Roscommon County, MI bridge conditions · every bridge in Roscommon County · Michigan bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.