US Bridges

I 90 over Keyser Creek

Fair

Stillwater County, Montana · 1.2M W Columbus · Structure no. I00090407+08621

Built
1971
54 years old, rebuilt 2014
Condition
Fair
inspected December 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
191 ft
3 main spans
Daily traffic
5,861
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Keyser Creek is a prestressed concrete stringer/multi-beam or girder carrying I 90 over Keyser Creek in Stillwater County, Montana. It was built in 1971 and reconstructed in 2014, 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 5,861 vehicles a day, roughly 18% of them trucks, projected to reach 6,300 by 2043. The structure is 191 ft (58.2 m) long and 44 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 90
CrossesKeyser Creek
Location1.2M W Columbus
RouteInterstate 90
CountyStillwater County
StateMontana
Coordinates45.65472, -109.266
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating52 US tons
Inventory rating27 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length191 ft (58.2 m)
Longest span76 ft (23.3 m)
Deck width44 ft (13.5 m)
Roadway width41 ft (12.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,861 (2023)
Projected traffic6,300 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 over Keyser Creek built?

It was built in 1971, making it 54 years old in 2025. It was reconstructed in 2014.

What condition is I 90 over Keyser Creek 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 I 90 over Keyser Creek carry?

About 5,861 vehicles per day (2023 count), of which roughly 18% are trucks.

How long is I 90 over Keyser Creek?

The structure is 191 ft (58.2 m) long with a longest span of 76 ft (23.3 m) and a deck 44 ft wide.

Who owns I 90 over Keyser Creek?

It is owned by the State Highway Agency.