US Bridges

I 90 Westbound over Boulder River

Fair

Jefferson County, Montana · 0.6M E Cardwell · Structure no. I00090256+08672

Built
1968
57 years old
Condition
Fair
inspected October 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
114 ft
2 main spans
Daily traffic
5,599
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 Westbound over Boulder River is a prestressed concrete stringer/multi-beam or girder carrying I 90 Westbound over Boulder River in Jefferson County, Montana. It was built in 1968, so it is 57 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 5,599 vehicles a day, roughly 18% of them trucks, projected to reach 6,214 by 2043. The structure is 114 ft (34.7 m) long and 38 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI 90 Westbound
CrossesBoulder River
Location0.6M E Cardwell
RouteInterstate 90
CountyJefferson County
StateMontana
Coordinates45.87046, -111.94281
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating59 US tons
Inventory rating45 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length114 ft (34.7 m)
Longest span56 ft (17.1 m)
Deck width38 ft (11.6 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,599 (2023)
Projected traffic6,214 by 2043
Trucks18%
Lanes on structure2
Traffic directionOne-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 proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was I 90 Westbound over Boulder River built?

It was built in 1968, making it 57 years old in 2025.

What condition is I 90 Westbound over Boulder 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 October 2023.

How much traffic does I 90 Westbound over Boulder River carry?

About 5,599 vehicles per day (2023 count), of which roughly 18% are trucks.

How long is I 90 Westbound over Boulder River?

The structure is 114 ft (34.7 m) long with a longest span of 56 ft (17.1 m) and a deck 38 ft wide.

Who owns I 90 Westbound over Boulder River?

It is owned by the State Highway Agency.