US Bridges

M-32 over S Br Thunder Bay River

Fair

Alpena County, Michigan · 7.3 MI W of Alpena · Structure no. 000000000000330

Built
1931
94 years old, rebuilt 1988
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
180 ft
3 main spans
Daily traffic
5,505
2007 count
Owner
State
State Highway Agency

About this bridge

M-32 over S Br Thunder Bay River is a steel stringer/multi-beam or girder carrying M-32 over S Br Thunder Bay River in Alpena County, Michigan. It was built in 1931 and reconstructed in 1988, so it is 94 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 5,505 vehicles a day, roughly 9% of them trucks, projected to reach 7,645 by 2018. The structure is 180 ft (54.9 m) long and 38 ft wide. If it were closed, the detour would be 14.9 mi (24 km).

Location

Open in Google Maps
CarriesM-32
CrossesS Br Thunder Bay River
Location7.3 MI W of Alpena
RouteState Highway 32
CountyAlpena County
StateMichigan
Coordinates45.06089, -83.58514
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating65.7 US tons
Inventory rating39.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length180 ft (54.9 m)
Longest span59 ft (17.9 m)
Deck width38 ft (11.7 m)
Roadway width35 ft (10.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,505 (2007)
Projected traffic7,645 by 2018
Trucks9%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed14.9 mi (24 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was M-32 over S Br Thunder Bay River built?

It was built in 1931, making it 94 years old in 2025. It was reconstructed in 1988.

What condition is M-32 over S Br Thunder Bay 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 July 2024.

How much traffic does M-32 over S Br Thunder Bay River carry?

About 5,505 vehicles per day (2007 count), of which roughly 9% are trucks.

How long is M-32 over S Br Thunder Bay River?

The structure is 180 ft (54.9 m) long with a longest span of 59 ft (17.9 m) and a deck 38 ft wide.

Who owns M-32 over S Br Thunder Bay River?

It is owned by the State Highway Agency.