US Bridges

M-25 over Black River Spillway

Fair

St. Clair County, Michigan · In Port Huron · Structure no. 000000000009981

Built
2000
25 years old
Condition
Fair
inspected November 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
165 ft
3 main spans
Daily traffic
40,250
2019 count
Owner
State
State Highway Agency

About this bridge

M-25 over Black River Spillway is a prestressed concrete stringer/multi-beam or girder carrying M-25 over Black River Spillway in St. Clair County, Michigan. It was built in 2000, so it is 25 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 40,250 vehicles a day, roughly 2% of them trucks, projected to reach 46,288 by 2039. The structure is 165 ft (50.3 m) long and 86 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

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CarriesM-25
CrossesBlack River Spillway
LocationIn Port Huron
RouteState Highway 136
CountySt. Clair County
StateMichigan
Coordinates43.01644, -82.45078
Functional classUrban Other Principal 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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating79.7 US tons
Inventory rating41.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 25 or greater
Structure length165 ft (50.3 m)
Longest span76 ft (23.1 m)
Deck width86 ft (26.1 m)
Roadway width64 ft (19.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic40,250 (2019)
Projected traffic46,288 by 2039
Trucks2%
Lanes on structure5
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 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-25 over Black River Spillway built?

It was built in 2000, making it 25 years old in 2025.

What condition is M-25 over Black River Spillway 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 November 2024.

How much traffic does M-25 over Black River Spillway carry?

About 40,250 vehicles per day (2019 count), of which roughly 2% are trucks.

How long is M-25 over Black River Spillway?

The structure is 165 ft (50.3 m) long with a longest span of 76 ft (23.1 m) and a deck 86 ft wide.

Who owns M-25 over Black River Spillway?

It is owned by the State Highway Agency.