US Bridges

331 Rabbit Obrien over Obrien CR

Fair

Lincoln County, Montana · Between Jcts W/4445 Loop · Structure no. 011404000000162

Built
1980
45 years old
Condition
Fair
inspected August 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
36 ft
1 main span
Daily traffic
40
1994 count
Owner
Federal
U.S. Forest Service

About this bridge

331 Rabbit Obrien over Obrien CR is a prestressed concrete stringer/multi-beam or girder carrying 331 Rabbit Obrien over Obrien CR in Lincoln County, Montana. It was built in 1980, so it is 45 years old, younger than the Montana average of 47 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 40 vehicles a day, projected to reach 60 by 2045. The structure is 36 ft (11.1 m) long and 16 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
Carries331 Rabbit Obrien
CrossesObrien CR
LocationBetween Jcts W/4445 Loop
RouteFederal Lands Road 331
CountyLincoln County
StateMontana
Coordinates48.48893, -115.8485
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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 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 geometry7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating34 US tons
Inventory rating26.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckOther
Main spans1
Design loadHS 20
Structure length36 ft (11.1 m)
Longest span35 ft (10.7 m)
Deck width16 ft (4.9 m)
Roadway width15 ft (4.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic40 (1994)
Projected traffic60 by 2045
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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 331 Rabbit Obrien over Obrien CR built?

It was built in 1980, making it 45 years old in 2025.

What condition is 331 Rabbit Obrien over Obrien CR 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 331 Rabbit Obrien over Obrien CR carry?

About 40 vehicles per day (1994 count).

How long is 331 Rabbit Obrien over Obrien CR?

The structure is 36 ft (11.1 m) long with a longest span of 35 ft (10.7 m) and a deck 16 ft wide.

Who owns 331 Rabbit Obrien over Obrien CR?

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