US Bridges

M-86 over Prairie River

Fair

St. Joseph County, Michigan · 5.4 MI SE of M-60 · Structure no. 000000000010282

Built
1999
26 years old
Condition
Fair
inspected September 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
89 ft
1 main span
Daily traffic
4,618
2022 count
Owner
State
State Highway Agency

About this bridge

M-86 over Prairie River is a prestressed concrete box beam or girders - multiple carrying M-86 over Prairie River in St. Joseph County, Michigan. It was built in 1999, so it is 26 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 4,618 vehicles a day, roughly 3% of them trucks. The structure is 89 ft (27.1 m) long and 51 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesM-86
CrossesPrairie River
Location5.4 MI SE of M-60
RouteState Highway 86
CountySt. Joseph County
StateMichigan
Coordinates41.92287, -85.54736
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionSeptember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourCountermeasures installed to correct a previously existing problem
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating107.1 US tons
Inventory rating57.9 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 25 or greater
Structure length89 ft (27.1 m)
Longest span89 ft (27.1 m)
Deck width51 ft (15.6 m)
Roadway width47 ft (14.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,618 (2022)
Projected traffic—
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
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—
NavigationNo navigation control on waterway

Frequently asked questions

When was M-86 over Prairie River built?

It was built in 1999, making it 26 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 4,618 vehicles per day (2022 count), of which roughly 3% are trucks.

How long is M-86 over Prairie River?

The structure is 89 ft (27.1 m) long with a longest span of 89 ft (27.1 m) and a deck 51 ft wide.

Who owns M-86 over Prairie River?

It is owned by the State Highway Agency.