US Bridges

Old M-107 over Union River

Poor

Ontonagon County, Michigan · 2.5 MI W of Silver City · Structure no. 000000000008508

Built
1976
49 years old
Condition
Poor
inspected October 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
75 ft
1 main span
Daily traffic
831
2007 count
Owner
County
County Highway Agency

About this bridge

Old M-107 over Union River is a steel stringer/multi-beam or girder carrying Old M-107 over Union River in Ontonagon County, Michigan. It was built in 1976, so it is 49 years old, older than the Michigan average of 48.3 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 831 vehicles a day, roughly 5% of them trucks, projected to reach 910 by 2018. The structure is 75 ft (22.8 m) long and 42 ft wide. If it were closed, the detour would be 75.2 mi (121 km).

Location

Open in Google Maps
CarriesOld M-107
CrossesUnion River
Location2.5 MI W of Silver City
RouteCounty Highway 0
CountyOntonagon County
StateMichigan
Coordinates46.81834, -89.61927
Functional classRural Major Collector

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck4 PoorAdvanced section loss, deterioration, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2024
Inspection intervalevery 12 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry8: Equal to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating102.3 US tons
Inventory rating61.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadH 20
Structure length75 ft (22.8 m)
Longest span75 ft (22.8 m)
Deck width42 ft (12.9 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic831 (2007)
Projected traffic910 by 2018
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed75.2 mi (121 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 Old M-107 over Union River built?

It was built in 1976, making it 49 years old in 2025.

What condition is Old M-107 over Union River in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in October 2024.

How much traffic does Old M-107 over Union River carry?

About 831 vehicles per day (2007 count), of which roughly 5% are trucks.

How long is Old M-107 over Union River?

The structure is 75 ft (22.8 m) long with a longest span of 75 ft (22.8 m) and a deck 42 ft wide.

Who owns Old M-107 over Union River?

It is owned by the County Highway Agency.