US Bridges

M-29 over Pine River

Fair

St. Clair County, Michigan · In ST Clair · Structure no. 000000000009977

Built
1975
50 years old
Condition
Fair
inspected May 2024
Type
Movable - Bascule
Steel
Length
200 ft
1 main span
Daily traffic
9,706
2021 count
Owner
State
State Highway Agency

About this bridge

M-29 over Pine River is a steel movable - bascule carrying M-29 over Pine River in St. Clair County, Michigan. It was built in 1975, so it is 50 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 9,706 vehicles a day, roughly 3% of them trucks, projected to reach 11,162 by 2041. The structure is 200 ft (61 m) long and 67 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesM-29
CrossesPine River
LocationIn ST Clair
RouteState Highway 29
CountySt. Clair County
StateMichigan
Coordinates42.82041, -82.48641
Functional classUrban Minor 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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 protection7 GoodSome minor problems.
Last inspectionMay 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
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 rating60 US tons
Inventory rating36 US tons

Structure

Structure typeMovable - Bascule
MaterialSteel
DeckOpen grating
Main spans1 (+2 approach)
Design loadHS 20
Structure length200 ft (61 m)
Longest span80 ft (24.4 m)
Deck width67 ft (20.3 m)
Roadway width52 ft (15.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic9,706 (2021)
Projected traffic11,162 by 2041
Trucks3%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed3.7 mi (6 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—
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was M-29 over Pine River built?

It was built in 1975, making it 50 years old in 2025.

What condition is M-29 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 May 2024.

How much traffic does M-29 over Pine River carry?

About 9,706 vehicles per day (2021 count), of which roughly 3% are trucks.

How long is M-29 over Pine River?

The structure is 200 ft (61 m) long with a longest span of 80 ft (24.4 m) and a deck 67 ft wide.

Who owns M-29 over Pine River?

It is owned by the State Highway Agency.