US Bridges

IRR BIA Route 1 over Main Canal

Fair

Valley County, Montana · 1.0 KM SW of Oswego · Structure no. 00000000000C614

Built
1976
49 years old
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
42 ft
1 main span
Daily traffic
1,200
2024 count
Owner
Federal
Bureau of Indian Affairs

About this bridge

IRR BIA Route 1 over Main Canal is a prestressed concrete stringer/multi-beam or girder carrying IRR BIA Route 1 over Main Canal in Valley County, Montana. It was built in 1976, so it is 49 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.

It carries about 1,200 vehicles a day, roughly 10% of them trucks, projected to reach 1,404 by 2044. The structure is 42 ft (12.8 m) long and 34 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

CarriesIRR BIA Route 1
CrossesMain Canal
Location1.0 KM SW of Oswego
RouteFederal Lands Road 1
StateMontana
Coordinates48.05147, -105.88728
Functional classRural Minor Arterial

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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; action required to protect exposed foundations
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating35.9 US tons
Inventory rating27 US tons

Structure

MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length42 ft (12.8 m)
Longest span40 ft (12.2 m)
Deck width34 ft (10.4 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic1,200 (2024)
Projected traffic1,404 by 2044
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerBureau of Indian Affairs
Maintained byBureau of Indian Affairs
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 IRR BIA Route 1 over Main Canal built?

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

What condition is IRR BIA Route 1 over Main Canal 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 October 2024.

How much traffic does IRR BIA Route 1 over Main Canal carry?

About 1,200 vehicles per day (2024 count), of which roughly 10% are trucks.

How long is IRR BIA Route 1 over Main Canal?

The structure is 42 ft (12.8 m) long with a longest span of 40 ft (12.2 m) and a deck 34 ft wide.

Who owns IRR BIA Route 1 over Main Canal?

It is owned by the Bureau of Indian Affairs.