US Bridges

I 90 over Int I-15

Fair

Silver Bow County, Montana · Butte · Structure no. I00090227+04551

Built
1963
62 years old, rebuilt 2017
Condition
Fair
inspected September 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
193 ft
1 main span
Daily traffic
5,476
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Int I-15 is a steel stringer/multi-beam or girder carrying I 90 over Int I-15 in Silver Bow County, Montana. It was built in 1963 and reconstructed in 2017, so it is 62 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 5,476 vehicles a day, roughly 20% of them trucks, projected to reach 5,832 by 2043. The structure is 193 ft (58.8 m) long and 41 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI 90
CrossesInt I-15
LocationButte
RouteInterstate 90
CountySilver Bow County
StateMontana
Coordinates45.97982, -112.48016
Functional classUrban 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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating40 US tons
Inventory rating20 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans1 (+2 approach)
Design loadHS 20
Structure length193 ft (58.8 m)
Longest span76 ft (23.2 m)
Deck width41 ft (12.5 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,476 (2023)
Projected traffic5,832 by 2043
Trucks20%
Lanes on structure2
Traffic directionOne-way traffic
CarriesOverpass structure at an interchange
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 Int I-15 built?

It was built in 1963, making it 62 years old in 2025. It was reconstructed in 2017.

What condition is I 90 over Int I-15 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 September 2024.

How much traffic does I 90 over Int I-15 carry?

About 5,476 vehicles per day (2023 count), of which roughly 20% are trucks.

How long is I 90 over Int I-15?

The structure is 193 ft (58.8 m) long with a longest span of 76 ft (23.2 m) and a deck 41 ft wide.

Who owns I 90 over Int I-15?

It is owned by the State Highway Agency.