US Bridges

M-24 over Cass River

Fair

Tuscola County, Michigan · 0.6 MI S of M-81 in Caro · Structure no. 000000000010428

Built
1941
84 years old, rebuilt 1989
Condition
Fair
inspected July 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
420 ft
7 main spans
Daily traffic
5,516
2007 count
Owner
State
State Highway Agency

About this bridge

M-24 over Cass River is a steel stringer/multi-beam or girder carrying M-24 over Cass River in Tuscola County, Michigan. It was built in 1941 and reconstructed in 1989, so it is 84 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 5,516 vehicles a day, roughly 8% of them trucks, projected to reach 7,316 by 2018. The structure is 420 ft (128 m) long and 43 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

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CarriesM-24
CrossesCass River
Location0.6 MI S of M-81 in Caro
RouteState Highway 24
CountyTuscola County
StateMichigan
Coordinates43.4836, -83.38685
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.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
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 adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating79.7 US tons
Inventory rating47.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans7
Design loadH 20
Structure length420 ft (128 m)
Longest span60 ft (18.2 m)
Deck width43 ft (13.1 m)
Roadway width35 ft (10.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,516 (2007)
Projected traffic7,316 by 2018
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 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-24 over Cass River built?

It was built in 1941, making it 84 years old in 2025. It was reconstructed in 1989.

What condition is M-24 over Cass 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-24 over Cass River carry?

About 5,516 vehicles per day (2007 count), of which roughly 8% are trucks.

How long is M-24 over Cass River?

The structure is 420 ft (128 m) long with a longest span of 60 ft (18.2 m) and a deck 43 ft wide.

Who owns M-24 over Cass River?

It is owned by the State Highway Agency.