US Bridges

County Line RD over Irrigation Canal 031

FairPosted for load

Teton County, Montana · 3M SE Fairfield · Structure no. L50481000+05001

Built
1949
76 years old
Condition
Fair
inspected December 2023
Type
Stringer/Multi-beam or Girder
Wood or Timber
Length
57 ft
3 main spans
Daily traffic
100
2025 count
Owner
County
County Highway Agency

About this bridge

County Line RD over Irrigation Canal 031 is a wood or timber stringer/multi-beam or girder carrying County Line RD over Irrigation Canal 031 in Teton County, Montana. It was built in 1949, so it is 76 years old, older 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. Its operating status is: posted for load restriction.

It carries about 100 vehicles a day, roughly 3% of them trucks, projected to reach 100 by 2040. The structure is 57 ft (17.4 m) long and 26 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

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CarriesCounty Line RD
CrossesIrrigation Canal 031
Location3M SE Fairfield
RouteCounty Highway 50481
CountyTeton County
StateMontana
Coordinates47.61134, -111.92921
Functional classRural Major Collector

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 inspectionDecember 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating32 US tons
Inventory rating20 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialWood or Timber
DeckWood or timber
Main spans3
Design loadH 15
Structure length57 ft (17.4 m)
Longest span17 ft (5.3 m)
Deck width26 ft (8 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2025)
Projected traffic100 by 2040
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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 County Line RD over Irrigation Canal 031 built?

It was built in 1949, making it 76 years old in 2025.

What condition is County Line RD over Irrigation Canal 031 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 December 2023.

How much traffic does County Line RD over Irrigation Canal 031 carry?

About 100 vehicles per day (2025 count), of which roughly 3% are trucks.

How long is County Line RD over Irrigation Canal 031?

The structure is 57 ft (17.4 m) long with a longest span of 17 ft (5.3 m) and a deck 26 ft wide.

Who owns County Line RD over Irrigation Canal 031?

It is owned by the County Highway Agency.