US Bridges

M-46 over Pine River

Fair

Gratiot County, Michigan · 0.6 MI E of County Line · Structure no. 000000000003127

Built
1936
89 years old, rebuilt 1994
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
70 ft
1 main span
Daily traffic
5,634
2007 count
Owner
State
State Highway Agency

About this bridge

M-46 over Pine River is a steel stringer/multi-beam or girder carrying M-46 over Pine River in Gratiot County, Michigan. It was built in 1936 and reconstructed in 1994, so it is 89 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 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 5,634 vehicles a day, roughly 9% of them trucks, projected to reach 7,954 by 2018. The structure is 70 ft (21.3 m) long and 47 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesM-46
CrossesPine River
Location0.6 MI E of County Line
RouteState Highway 46
CountyGratiot County
StateMichigan
Coordinates43.40827, -84.83334
Functional classRural Principal Arterial - Other

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
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 rating96.1 US tons
Inventory rating57.5 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 25 or greater
Structure length70 ft (21.3 m)
Longest span70 ft (21.3 m)
Deck width47 ft (14.4 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,634 (2007)
Projected traffic7,954 by 2018
Trucks9%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedDeck replacement with only incidental widening
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was M-46 over Pine River built?

It was built in 1936, making it 89 years old in 2025. It was reconstructed in 1994.

What condition is M-46 over Pine 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 June 2023.

How much traffic does M-46 over Pine River carry?

About 5,634 vehicles per day (2007 count), of which roughly 9% are trucks.

How long is M-46 over Pine River?

The structure is 70 ft (21.3 m) long with a longest span of 70 ft (21.3 m) and a deck 47 ft wide.

Who owns M-46 over Pine River?

It is owned by the State Highway Agency.