M-20 over N Br Chippewa River
Isabella County, Michigan · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- M-20 over N Br Chippewa River in Isabella 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 1934 and reconstructed in 1964, making it 91 years old at the 2025 inventory.
- It carries about 8,359 vehicles a day (traffic count year 2007).
- Its listed owner is the state highway agency.
- It is one of 72 of the 183 inventoried bridges in Isabella County rated fair (39.3%); 26 (14.2%) 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 March 2023, on a 24-month routine inspection cycle.
- It is coded scour critical (NBI item 113 = 3): scour critical: foundations unstable for the assessed or calculated scour.
- 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 → (43.59704, -84.85496)
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 | Steel stringer or multi-beam girder |
| Length | about 49 ft |
| Location | 4.5 Mi W of US-27BR |
| NBI structure number | 000000000004264 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | March 2023 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 3: scour critical: foundations unstable for the assessed or calculated scour |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Michigan department of transportation.
Busiest bridges in Isabella County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Pickard Avenue over Chippewa River | 1979 | 16,211 | Fair |
| M-20 over Chippewa River | 1996 | 10,842 | Good |
| US-127 NB over Little Salt River | 1961 | 10,457 | Fair |
| US-127 SB over Little Salt River | 1961 | 10,457 | Fair |
| Mission Road over Ann Arbor Railroad | 2005 | 9,200 | Good |
| Mission Road over North Br Chippewa River | 2008 | 9,019 | Good |
All bridges nearby: Isabella County, MI bridge conditions · every bridge in Isabella County · Michigan bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.