US Bridges

M-64 over Mineral River

Fair

Ontonagon County, Michigan · 4.6 MI S of M-107 · Structure no. 000000000008465

Built
1954
71 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
169 ft
3 main spans
Daily traffic
500
2022 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 1954, so it is 71 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 500 vehicles a day, roughly 6% of them trucks, projected to reach 640 by 2042. The structure is 169 ft (51.5 m) long and 35 ft wide. If it were closed, the detour would be 21.7 mi (35 km).

Location

Open in Google Maps
CarriesM-64
CrossesMineral River
Location4.6 MI S of M-107
RouteState Highway 64
CountyOntonagon County
StateMichigan
Coordinates46.76219, -89.57387
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 protection8 Very GoodNo problems noted.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy6: Equal to present minimum criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating92.2 US tons
Inventory rating55 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length169 ft (51.5 m)
Longest span70 ft (21.3 m)
Deck width35 ft (10.8 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic500 (2022)
Projected traffic640 by 2042
Trucks6%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed21.7 mi (35 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-64 over Mineral River built?

It was built in 1954, making it 71 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 500 vehicles per day (2022 count), of which roughly 6% are trucks.

How long is M-64 over Mineral River?

The structure is 169 ft (51.5 m) long with a longest span of 70 ft (21.3 m) and a deck 35 ft wide.

Who owns M-64 over Mineral River?

It is owned by the State Highway Agency.