US Bridges

I 90 over Irrigation Canal

Fair

Big Horn County, Montana · 3.1M S Hardin · Structure no. I00090498+04621

Built
1971
54 years old
Condition
Fair
inspected March 2024
Type
Culvert
Steel
Length
25 ft
2 main spans
Daily traffic
8,516
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Irrigation Canal is a steel culvert carrying I 90 over Irrigation Canal in Big Horn County, Montana. It was built in 1971, so it is 54 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 5 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 8,516 vehicles a day, roughly 18% of them trucks, projected to reach 8,942 by 2043. The structure is 25 ft (7.7 m) long. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 90
CrossesIrrigation Canal
Location3.1M S Hardin
RouteInterstate 90
CountyBig Horn County
StateMontana
Coordinates45.73356, -107.5678
Functional classRural Principal Arterial - Interstate

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating110.1 US tons
Inventory rating110.1 US tons

Structure

Structure typeCulvert
MaterialSteel
DeckNot applicable
Main spans2
Design loadHS 20
Structure length25 ft (7.7 m)
Longest span11 ft (3.3 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic8,516 (2023)
Projected traffic8,942 by 2043
Trucks18%
Lanes on structure6
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes
Strategic Highway NetworkInterstate STRAHNET route

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$417,000
NavigationNo navigation control on waterway

Frequently asked questions

When was I 90 over Irrigation Canal built?

It was built in 1971, making it 54 years old in 2025.

What condition is I 90 over Irrigation 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 March 2024.

How much traffic does I 90 over Irrigation Canal carry?

About 8,516 vehicles per day (2023 count), of which roughly 18% are trucks.

How long is I 90 over Irrigation Canal?

The structure is 25 ft (7.7 m) long with a longest span of 11 ft (3.3 m).

Who owns I 90 over Irrigation Canal?

It is owned by the State Highway Agency.