US Bridges

I 90 over Sep Garrison Frontage RD

Fair

Powell County, Montana · 2.5M W Garrison · Structure no. I00090171+07792

Built
1973
52 years old
Condition
Fair
inspected August 2024
Type
Slab
Concrete Continuous
Length
78 ft
3 main spans
Daily traffic
5,136
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Sep Garrison Frontage RD is a concrete continuous slab carrying I 90 over Sep Garrison Frontage RD in Powell County, Montana. It was built in 1973, so it is 52 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 5,136 vehicles a day, roughly 22% of them trucks, projected to reach 5,469 by 2043. The structure is 78 ft (23.8 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
CrossesSep Garrison Frontage RD
Location2.5M W Garrison
RouteInterstate 90
CountyPowell County
StateMontana
Coordinates46.54261, -112.84681
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Last inspectionAugust 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating48 US tons
Inventory rating37 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length78 ft (23.8 m)
Longest span30 ft (9.1 m)
Deck width44 ft (13.5 m)
Roadway width42 ft (12.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,136 (2023)
Projected traffic5,469 by 2043
Trucks22%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
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—
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 90 over Sep Garrison Frontage RD built?

It was built in 1973, making it 52 years old in 2025.

What condition is I 90 over Sep Garrison Frontage RD 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 August 2024.

How much traffic does I 90 over Sep Garrison Frontage RD carry?

About 5,136 vehicles per day (2023 count), of which roughly 22% are trucks.

How long is I 90 over Sep Garrison Frontage RD?

The structure is 78 ft (23.8 m) long with a longest span of 30 ft (9.1 m) and a deck 44 ft wide.

Who owns I 90 over Sep Garrison Frontage RD?

It is owned by the State Highway Agency.