M-21 over Grand River
GoodKent County, Michigan · 6.4 MI E of I-96 · Structure no. 000000000004854
- Built
- 2010
- 15 years old
- Condition
- Good
- inspected October 2024
- Type
- Stringer/Multi-beam or Girder
- Prestressed Concrete
- Length
- 480 ft
- 6 main spans
- Daily traffic
- 23,900
- 2009 count
- Owner
- State
- State Highway Agency
About this bridge
M-21 over Grand River is a prestressed concrete stringer/multi-beam or girder carrying M-21 over Grand River in Kent County, Michigan. It was built in 2010, so it is 15 years old, younger than the Michigan average of 48.3 years.
The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
It carries about 23,900 vehicles a day, roughly 4% of them trucks, projected to reach 30,600 by 2029. The structure is 480 ft (146.3 m) long and 83 ft wide. If it were closed, the detour would be 9.9 mi (16 km).
Location
Open in Google MapsCondition and inspection
All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.
| Component | Rating | Meaning |
|---|---|---|
| Deck | 7 Good | Some minor problems. |
| Superstructure | 8 Very Good | No problems noted. |
| Substructure | 7 Good | Some minor problems. |
| Channel and channel protection | 6 Satisfactory | Structural elements show some minor deterioration. |
Structure
Traffic and service
Ownership and planned work
Frequently asked questions
When was M-21 over Grand River built?
It was built in 2010, making it 15 years old in 2025.
What condition is M-21 over Grand River in?
The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in October 2024.
How much traffic does M-21 over Grand River carry?
About 23,900 vehicles per day (2009 count), of which roughly 4% are trucks.
How long is M-21 over Grand River?
The structure is 480 ft (146.3 m) long with a longest span of 83 ft (25.2 m) and a deck 83 ft wide.
Who owns M-21 over Grand River?
It is owned by the State Highway Agency.