US Bridges

US-31 NB over S Branch Pentwater River

Fair

Oceana County, Michigan · 3 MI NW of Hart · Structure no. 000000000008335

Built
1977
48 years old
Condition
Fair
inspected November 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
210 ft
3 main spans
Daily traffic
4,171
2007 count
Owner
State
State Highway Agency

About this bridge

US-31 NB over S Branch Pentwater River is a steel stringer/multi-beam or girder carrying US-31 NB over S Branch Pentwater River in Oceana County, Michigan. It was built in 1977, so it is 48 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 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 4,171 vehicles a day, roughly 11% of them trucks, projected to reach 5,668 by 2018. The structure is 210 ft (64 m) long and 44 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

CarriesUS-31 NB
CrossesS Branch Pentwater River
Location3 MI NW of Hart
RouteU.S. Route 31
Coordinates43.74148, -86.38927
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
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.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionNovember 2023
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 geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating92.5 US tons
Inventory rating55.3 US tons

Structure

MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 25 or greater
Structure length210 ft (64 m)
Longest span95 ft (28.9 m)
Deck width44 ft (13.4 m)
Roadway width41 ft (12.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,171 (2007)
Projected traffic5,668 by 2018
Trucks11%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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$188,000
NavigationNo navigation control on waterway

Frequently asked questions

When was US-31 NB over S Branch Pentwater River built?

It was built in 1977, making it 48 years old in 2025.

What condition is US-31 NB over S Branch Pentwater 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 November 2023.

How much traffic does US-31 NB over S Branch Pentwater River carry?

About 4,171 vehicles per day (2007 count), of which roughly 11% are trucks.

How long is US-31 NB over S Branch Pentwater River?

The structure is 210 ft (64 m) long with a longest span of 95 ft (28.9 m) and a deck 44 ft wide.

Who owns US-31 NB over S Branch Pentwater River?

It is owned by the State Highway Agency.