US Bridges

Forest Road 360 over Iron River

Fair

Ontonagon County, Michigan · 6 MI N 4 MI W of Bergland · Structure no. 090701000001021

Built
1972
53 years old, rebuilt 1984
Condition
Fair
inspected September 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
85 ft
1 main span
Daily traffic
50
Owner
Federal
U.S. Forest Service

About this bridge

Forest Road 360 over Iron River is a steel stringer/multi-beam or girder carrying Forest Road 360 over Iron River in Ontonagon County, Michigan. It was built in 1972 and reconstructed in 1984, so it is 53 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 50 vehicles a day, projected to reach 75 by 2045. The structure is 85 ft (25.9 m) long and 26 ft wide. If it were closed, the detour would be 29.8 mi (48 km).

Location

Open in Google Maps
CarriesForest Road 360
CrossesIron River
Location6 MI N 4 MI W of Bergland
RouteFederal Lands Road 360
CountyOntonagon County
StateMichigan
Coordinates46.67835, -89.65137
Functional classRural Local

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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating63.9 US tons
Inventory rating49.3 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length85 ft (25.9 m)
Longest span82 ft (25 m)
Deck width26 ft (7.9 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (—)
Projected traffic75 by 2045
Trucks—
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed29.8 mi (48 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerU.S. Forest Service
Maintained byU.S. Forest Service
Historic statusHistorical significance not determinable at this time
Work proposedOther structural work, including hydraulic replacements
Estimated improvement cost$1,000
NavigationNo navigation control on waterway

Frequently asked questions

When was Forest Road 360 over Iron River built?

It was built in 1972, making it 53 years old in 2025. It was reconstructed in 1984.

What condition is Forest Road 360 over Iron 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 September 2024.

How much traffic does Forest Road 360 over Iron River carry?

About 50 vehicles per day (latest count).

How long is Forest Road 360 over Iron River?

The structure is 85 ft (25.9 m) long with a longest span of 82 ft (25 m) and a deck 26 ft wide.

Who owns Forest Road 360 over Iron River?

It is owned by the U.S. Forest Service.