County Route 510 over Yellow Dog River
Marquette County, Michigan · rated Fair in the 2025 National Bridge Inventory
United States Bridge Conditions2025 National Bridge Inventory, FHWACompiled
- County Route 510 over Yellow Dog River in Marquette 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 1973, making it 52 years old at the 2025 inventory.
- It carries about 314 vehicles a day (traffic count year 2001).
- Its listed owner is the county highway agency.
- It is one of 59 of the 147 inventoried bridges in Marquette County rated fair (40.1%); 19 (12.9%) 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, superstructure 6 to 5.
- Its most recent inspection on record is dated October 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 → (46.72663, -87.71496)
Component ratings
| Component | Rating (2024) | Rating (2025) | FHWA scale meaning |
|---|---|---|---|
| Deck | 8 | 7 | Good condition |
| Superstructure | 6 | 5 | Fair condition |
| Substructure | 7 | 7 | Good condition |
Bridge details
| Structure | Steel stringer or multi-beam girder |
| Length | about 69 ft |
| Location | 6 Mi South of Big Bay |
| NBI structure number | 000000000006556 |
| Condition class | Fair |
| Traffic status (item 41) | Open, no restriction |
| Last inspection (item 90) | October 2024 |
| Inspection interval (item 91) | 24 months |
| Scour (item 113) | 8: foundations stable, scour above the top of the footing |
Source: FHWA National Bridge Inventory, 2025 data as reported by the Michigan department of transportation.
Busiest bridges in Marquette County
| Bridge | Built | Vehicles/day | Condition |
|---|---|---|---|
| Us-41|m-28 over Carp River | 1936 | 23,600 | Fair |
| US-41 over Carp Creek | 1979 | 14,675 | Good |
| US-41 over Ls&i RR | 1979 | 13,542 | Fair |
| M-28 over Chocolay River | 2005 | 9,335 | Good |
| US-41 NB over Carp River | 1955 | 8,662 | Fair |
| US-41 SB over Carp River | 1958 | 8,662 | Fair |
All bridges nearby: Marquette County, MI bridge conditions · every bridge in Marquette County · Michigan bridges.
Background: how bridge ratings work · what "poor" and "structurally deficient" actually mean · how often bridges are inspected.