US Bridges

M-106 over Portage River

Poor

Jackson County, Michigan · 3 MI NE of I-94 · Structure no. 000000000004387

Built
1976
49 years old
Condition
Poor
inspected August 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
90 ft
2 main spans
Daily traffic
6,730
2007 count
Owner
State
State Highway Agency

About this bridge

M-106 over Portage River is a prestressed concrete stringer/multi-beam or girder carrying M-106 over Portage River in Jackson 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 6,730 vehicles a day, roughly 3% of them trucks, projected to reach 11,467 by 2018. The structure is 90 ft (27.4 m) long and 51 ft wide. If it were closed, the detour would be 8.7 mi (14 km).

Location

Open in Google Maps
CarriesM-106
CrossesPortage River
Location3 MI NE of I-94
RouteState Highway 106
CountyJackson County
StateMichigan
Coordinates42.31213, -84.38711
Functional classRural Minor Arterial

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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50 US tons
Inventory rating30 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length90 ft (27.4 m)
Longest span43 ft (13.1 m)
Deck width51 ft (15.4 m)
Roadway width48 ft (14.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic6,730 (2007)
Projected traffic11,467 by 2018
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.7 mi (14 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-106 over Portage River built?

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

What condition is M-106 over Portage 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 August 2024.

How much traffic does M-106 over Portage River carry?

About 6,730 vehicles per day (2007 count), of which roughly 3% are trucks.

How long is M-106 over Portage River?

The structure is 90 ft (27.4 m) long with a longest span of 43 ft (13.1 m) and a deck 51 ft wide.

Who owns M-106 over Portage River?

It is owned by the State Highway Agency.