US Bridges

M-28 over So Br Ontonagon River

Good

Ontonagon County, Michigan · 4.7 MI W of US-45 (ewen) · Structure no. 000000000008488

Built
1990
35 years old
Condition
Good
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
309 ft
3 main spans
Daily traffic
2,398
2007 count
Owner
State
State Highway Agency

About this bridge

M-28 over So Br Ontonagon River is a prestressed concrete stringer/multi-beam or girder carrying M-28 over So Br Ontonagon River in Ontonagon County, Michigan. It was built in 1990, so it is 35 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 2,398 vehicles a day, roughly 11% of them trucks, projected to reach 3,152 by 2018. The structure is 309 ft (94.2 m) long and 51 ft wide. If it were closed, the detour would be 39.8 mi (64 km).

Location

Open in Google Maps
CarriesM-28
CrossesSo Br Ontonagon River
Location4.7 MI W of US-45 (ewen)
RouteState Highway 28
CountyOntonagon County
StateMichigan
Coordinates46.53473, -89.27625
Functional classRural Principal Arterial - Other

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure8 Very GoodNo problems noted.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating78.3 US tons
Inventory rating48.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 25 or greater
Structure length309 ft (94.2 m)
Longest span104 ft (31.7 m)
Deck width51 ft (15.6 m)
Roadway width48 ft (14.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,398 (2007)
Projected traffic3,152 by 2018
Trucks11%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed39.8 mi (64 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-28 over So Br Ontonagon River built?

It was built in 1990, making it 35 years old in 2025.

What condition is M-28 over So Br Ontonagon 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 August 2023.

How much traffic does M-28 over So Br Ontonagon River carry?

About 2,398 vehicles per day (2007 count), of which roughly 11% are trucks.

How long is M-28 over So Br Ontonagon River?

The structure is 309 ft (94.2 m) long with a longest span of 104 ft (31.7 m) and a deck 51 ft wide.

Who owns M-28 over So Br Ontonagon River?

It is owned by the State Highway Agency.