US Bridges

I 15 over Int Ulm

Fair

Cascade County, Montana · Ulm · Structure no. I00015270+04311

Built
1958
67 years old
Condition
Fair
inspected March 2023
Type
Tee Beam
Concrete Continuous
Length
130 ft
3 main spans
Daily traffic
3,145
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 over Int Ulm is a concrete continuous tee beam carrying I 15 over Int Ulm in Cascade County, Montana. It was built in 1958, so it is 67 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 3,145 vehicles a day, roughly 12% of them trucks, projected to reach 3,301 by 2043. The structure is 130 ft (39.6 m) long and 47 ft wide.

Location

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CarriesI 15
CrossesInt Ulm
LocationUlm
RouteInterstate 15
CountyCascade County
StateMontana
Coordinates47.43367, -111.50691
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionMarch 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating22.8 US tons
Inventory rating13.6 US tons

Structure

Structure typeTee Beam
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length130 ft (39.6 m)
Longest span50 ft (15.2 m)
Deck width47 ft (14.3 m)
Roadway width44 ft (13.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,145 (2023)
Projected traffic3,301 by 2043
Trucks12%
Lanes on structure2
Traffic directionOne-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed—
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 15 over Int Ulm built?

It was built in 1958, making it 67 years old in 2025.

What condition is I 15 over Int Ulm 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 March 2023.

How much traffic does I 15 over Int Ulm carry?

About 3,145 vehicles per day (2023 count), of which roughly 12% are trucks.

How long is I 15 over Int Ulm?

The structure is 130 ft (39.6 m) long with a longest span of 50 ft (15.2 m) and a deck 47 ft wide.

Who owns I 15 over Int Ulm?

It is owned by the State Highway Agency.