US Bridges

FDR3500 over E Br Ontonagon River

Fair

Houghton County, Michigan · 8 MI SW of Sidnaw · Structure no. 090704000034743

Built
2021
4 years old
Condition
Fair
inspected September 2024
Type
Slab
Wood or Timber
Length
31 ft
1 main span
Daily traffic
20
2021 count
Owner
Federal
U.S. Forest Service

About this bridge

FDR3500 over E Br Ontonagon River is a wood or timber slab carrying FDR3500 over E Br Ontonagon River in Houghton County, Michigan. It was built in 2021, so it is 4 years old, younger 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 20 vehicles a day, projected to reach 30 by 2045. The structure is 31 ft (9.3 m) long and 18 ft wide. If it were closed, the detour would be 16.8 mi (27 km).

Location

Open in Google Maps
CarriesFDR3500
CrossesE Br Ontonagon River
Location8 MI SW of Sidnaw
RouteFederal Lands Road 3500
CountyHoughton County
StateMichigan
Coordinates46.44602, -88.76992
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating64.3 US tons
Inventory rating49.6 US tons

Structure

Structure typeSlab
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadOther
Structure length31 ft (9.3 m)
Longest span29 ft (8.8 m)
Deck width18 ft (5.5 m)
Roadway width16 ft (4.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic20 (2021)
Projected traffic30 by 2045
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed16.8 mi (27 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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was FDR3500 over E Br Ontonagon River built?

It was built in 2021, making it 4 years old in 2025.

What condition is FDR3500 over E Br Ontonagon 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 FDR3500 over E Br Ontonagon River carry?

About 20 vehicles per day (2021 count).

How long is FDR3500 over E Br Ontonagon River?

The structure is 31 ft (9.3 m) long with a longest span of 29 ft (8.8 m) and a deck 18 ft wide.

Who owns FDR3500 over E Br Ontonagon River?

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