US Bridges

I 90 over Grant Creek

Good

Missoula County, Montana · Reserve ST Int Missoula · Structure no. I00090101+07001

Built
1965
60 years old, rebuilt 1990
Condition
Good
inspected October 2023
Type
Culvert
Concrete
Length
32 ft
1 main span
Daily traffic
27,328
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Grant Creek is a concrete culvert carrying I 90 over Grant Creek in Missoula County, Montana. It was built in 1965 and reconstructed in 1990, so it is 60 years old, older than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 27,328 vehicles a day, roughly 9% of them trucks, projected to reach 29,104 by 2043. The structure is 32 ft (9.9 m) long. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesI 90
CrossesGrant Creek
LocationReserve ST Int Missoula
RouteInterstate 90
CountyMissoula County
StateMontana
Coordinates46.9137, -114.03451
Functional classUrban Principal Arterial - Interstate

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Culvert7 GoodSome minor problems.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation7: Better than present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating45.3 US tons
Inventory rating35.1 US tons

Structure

Structure typeCulvert
MaterialConcrete
DeckNot applicable
Main spans1
Design loadHS 20
Structure length32 ft (9.9 m)
Longest span14 ft (4.3 m)
Deck width0 ft (0 m)
Roadway width0 ft (0 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic27,328 (2023)
Projected traffic29,104 by 2043
Trucks9%
Lanes on structure9
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed123.7 mi (199 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$804,000
NavigationNo navigation control on waterway

Frequently asked questions

When was I 90 over Grant Creek built?

It was built in 1965, making it 60 years old in 2025. It was reconstructed in 1990.

What condition is I 90 over Grant Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in October 2023.

How much traffic does I 90 over Grant Creek carry?

About 27,328 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is I 90 over Grant Creek?

The structure is 32 ft (9.9 m) long with a longest span of 14 ft (4.3 m).

Who owns I 90 over Grant Creek?

It is owned by the State Highway Agency.