US Bridges

I 15 over Sep Roe LN

Fair

Beaverhead County, Montana · 6.2M S Clark Canyon Dam · Structure no. I00015038+07802

Built
1980
45 years old
Condition
Fair
inspected January 2025
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
113 ft
3 main spans
Daily traffic
2,116
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 over Sep Roe LN is a prestressed concrete stringer/multi-beam or girder carrying I 15 over Sep Roe LN in Beaverhead County, Montana. It was built in 1980, so it is 45 years old, younger 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 2,116 vehicles a day, roughly 25% of them trucks, projected to reach 2,264 by 2043. The structure is 113 ft (34.4 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 15
CrossesSep Roe LN
Location6.2M S Clark Canyon Dam
RouteInterstate 15
CountyBeaverhead County
StateMontana
Coordinates44.9206, -112.82606
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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionJanuary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating58 US tons
Inventory rating43 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length113 ft (34.4 m)
Longest span41 ft (12.6 m)
Deck width44 ft (13.4 m)
Roadway width41 ft (12.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,116 (2023)
Projected traffic2,264 by 2043
Trucks25%
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 15 over Sep Roe LN built?

It was built in 1980, making it 45 years old in 2025.

What condition is I 15 over Sep Roe LN 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 January 2025.

How much traffic does I 15 over Sep Roe LN carry?

About 2,116 vehicles per day (2023 count), of which roughly 25% are trucks.

How long is I 15 over Sep Roe LN?

The structure is 113 ft (34.4 m) long with a longest span of 41 ft (12.6 m) and a deck 44 ft wide.

Who owns I 15 over Sep Roe LN?

It is owned by the State Highway Agency.