US Bridges

M-86 over Prairie River

Fair

St. Joseph County, Michigan · 3.8 MI W of M-66 · Structure no. 000000000010283

Built
2016
9 years old
Condition
Fair
inspected September 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
104 ft
1 main span
Daily traffic
4,825
2015 count
Owner
State
State Highway Agency

About this bridge

M-86 over Prairie River is a prestressed concrete stringer/multi-beam or girder carrying M-86 over Prairie River in St. Joseph County, Michigan. It was built in 2016, so it is 9 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 4,825 vehicles a day, roughly 8% of them trucks, projected to reach 5,549 by 2035. The structure is 104 ft (31.7 m) long and 42 ft wide. If it were closed, the detour would be 1.9 mi (3 km).

Location

Open in Google Maps
CarriesM-86
CrossesPrairie River
Location3.8 MI W of M-66
RouteState Highway 86
CountySt. Joseph County
StateMichigan
Coordinates41.91903, -85.48148
Functional classRural 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
Deck8 Very GoodNo problems noted.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure8 Very GoodNo problems noted.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating89.3 US tons
Inventory rating58.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadGreater than HL 93
Structure length104 ft (31.7 m)
Longest span101 ft (30.8 m)
Deck width42 ft (12.9 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,825 (2015)
Projected traffic5,549 by 2035
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.9 mi (3 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusListed on the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was M-86 over Prairie River built?

It was built in 2016, making it 9 years old in 2025.

What condition is M-86 over Prairie 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 September 2023.

How much traffic does M-86 over Prairie River carry?

About 4,825 vehicles per day (2015 count), of which roughly 8% are trucks.

How long is M-86 over Prairie River?

The structure is 104 ft (31.7 m) long with a longest span of 101 ft (30.8 m) and a deck 42 ft wide.

Who owns M-86 over Prairie River?

It is owned by the State Highway Agency.