US Bridges

M-64 over Potato River

Fair

Ontonagon County, Michigan · 3.6 MI SW of US-45 · Structure no. 000000000008476

Built
1952
73 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
149 ft
3 main spans
Daily traffic
2,025
2013 count
Owner
State
State Highway Agency

About this bridge

M-64 over Potato River is a steel stringer/multi-beam or girder carrying M-64 over Potato River in Ontonagon County, Michigan. It was built in 1952, so it is 73 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 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 2,025 vehicles a day, roughly 5% of them trucks, projected to reach 2,350 by 2033. The structure is 149 ft (45.4 m) long and 33 ft wide. If it were closed, the detour would be 60.3 mi (97 km).

Location

Open in Google Maps
CarriesM-64
CrossesPotato River
Location3.6 MI SW of US-45
RouteState Highway 64
CountyOntonagon County
StateMichigan
Coordinates46.85206, -89.38663
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation6: Equal to present minimum criteria
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating67.5 US tons
Inventory rating40.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length149 ft (45.4 m)
Longest span60 ft (18.3 m)
Deck width33 ft (10.2 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,025 (2013)
Projected traffic2,350 by 2033
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed60.3 mi (97 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 proposedDeck replacement with only incidental widening
Estimated improvement cost$115,000
NavigationNo navigation control on waterway

Frequently asked questions

When was M-64 over Potato River built?

It was built in 1952, making it 73 years old in 2025.

What condition is M-64 over Potato 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 August 2024.

How much traffic does M-64 over Potato River carry?

About 2,025 vehicles per day (2013 count), of which roughly 5% are trucks.

How long is M-64 over Potato River?

The structure is 149 ft (45.4 m) long with a longest span of 60 ft (18.3 m) and a deck 33 ft wide.

Who owns M-64 over Potato River?

It is owned by the State Highway Agency.