US-31 over Big Sable River
FairMason County, Michigan · 4.9 MI S of Manistee Col · Structure no. 000000000006642
- Built
- 1959
- 66 years old
- Condition
- Fair
- inspected May 2024
- Type
- Box Beam or Girders - Multiple
- Prestressed Concrete
- Length
- 60 ft
- 1 main span
- Daily traffic
- 6,578
- 2007 count
- Owner
- State
- State Highway Agency
About this bridge
US-31 over Big Sable River is a prestressed concrete box beam or girders - multiple carrying US-31 over Big Sable River in Mason County, Michigan. It was built in 1959, so it is 66 years old, older than the Michigan average of 48.3 years.
The most recent inspection reported to the Federal Highway Administration rates it in fair condition with a lowest component rating of 5 out of 9. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
It carries about 6,578 vehicles a day, roughly 8% of them trucks, projected to reach 9,001 by 2018. The structure is 60 ft (18.2 m) long and 47 ft wide. If it were closed, the detour would be 3.1 mi (5 km).
Location
Open in Google MapsCondition and inspection
The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 6 Satisfactory | Structural elements show some minor deterioration. |
| Superstructure | 5 Fair | All primary structural elements are sound but may have minor section loss, cracking, spalling or scour. |
| Substructure | 6 Satisfactory | Structural elements show some minor deterioration. |
| Channel and channel protection | 7 Good | Some minor problems. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was US-31 over Big Sable River built?
It was built in 1959, making it 66 years old in 2025.
What condition is US-31 over Big Sable River in?
The National Bridge Inventory rates it in fair condition. The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound. The last reported inspection was in May 2024.
How much traffic does US-31 over Big Sable River carry?
About 6,578 vehicles per day (2007 count), of which roughly 8% are trucks.
How long is US-31 over Big Sable River?
The structure is 60 ft (18.2 m) long with a longest span of 60 ft (18.2 m) and a deck 47 ft wide.
Who owns US-31 over Big Sable River?
It is owned by the State Highway Agency.