US Bridges

M-21 over Maple River

Fair

Clinton County, Michigan · In Ovid · Structure no. 000000000001891

Built
1997
28 years old
Condition
Fair
inspected October 2024
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
91 ft
1 main span
Daily traffic
6,505
2007 count
Owner
State
State Highway Agency

About this bridge

M-21 over Maple River is a prestressed concrete box beam or girders - multiple carrying M-21 over Maple River in Clinton County, Michigan. It was built in 1997, so it is 28 years old, younger 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 6 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 6,505 vehicles a day, roughly 6% of them trucks, projected to reach 8,895 by 2018. The structure is 91 ft (27.7 m) long and 47 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesM-21
CrossesMaple River
LocationIn Ovid
RouteState Highway 21
CountyClinton County
StateMichigan
Coordinates43.00085, -84.37022
Functional classRural Minor Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating107.1 US tons
Inventory rating66.8 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 25 or greater
Structure length91 ft (27.7 m)
Longest span88 ft (26.9 m)
Deck width47 ft (14.4 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,505 (2007)
Projected traffic8,895 by 2018
Trucks6%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was M-21 over Maple River built?

It was built in 1997, making it 28 years old in 2025.

What condition is M-21 over Maple 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 October 2024.

How much traffic does M-21 over Maple River carry?

About 6,505 vehicles per day (2007 count), of which roughly 6% are trucks.

How long is M-21 over Maple River?

The structure is 91 ft (27.7 m) long with a longest span of 88 ft (26.9 m) and a deck 47 ft wide.

Who owns M-21 over Maple River?

It is owned by the State Highway Agency.