US Bridges

M-64 over Mineral River

Fair

Ontonagon County, Michigan · 6.7 MI S of M-107 · Structure no. 000000000008464

Built
1939
86 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
40 ft
1 main span
Daily traffic
1,175
2007 count
Owner
State
State Highway Agency

About this bridge

M-64 over Mineral River is a steel stringer/multi-beam or girder carrying M-64 over Mineral River in Ontonagon County, Michigan. It was built in 1939, so it is 86 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 1,175 vehicles a day, roughly 8% of them trucks, projected to reach 1,126 by 2018. The structure is 40 ft (12.2 m) long and 40 ft wide. If it were closed, the detour would be 54.1 mi (87 km).

Location

Open in Google Maps
CarriesM-64
CrossesMineral River
Location6.7 MI S of M-107
RouteState Highway 64
CountyOntonagon County
StateMichigan
Coordinates46.73341, -89.56294
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
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 geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating59.6 US tons
Inventory rating37.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadH 20
Structure length40 ft (12.2 m)
Longest span39 ft (11.8 m)
Deck width40 ft (12.3 m)
Roadway width35 ft (10.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,175 (2007)
Projected traffic1,126 by 2018
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed54.1 mi (87 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—
NavigationNo navigation control on waterway

Frequently asked questions

When was M-64 over Mineral River built?

It was built in 1939, making it 86 years old in 2025.

What condition is M-64 over Mineral 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 Mineral River carry?

About 1,175 vehicles per day (2007 count), of which roughly 8% are trucks.

How long is M-64 over Mineral River?

The structure is 40 ft (12.2 m) long with a longest span of 39 ft (11.8 m) and a deck 40 ft wide.

Who owns M-64 over Mineral River?

It is owned by the State Highway Agency.