US Bridges

I 15 over Sep Local Road

Fair

Beaverhead County, Montana · 2.5M S Dillon · Structure no. I00015060+09941

Built
1983
42 years old
Condition
Fair
inspected January 2025
Type
Slab
Concrete Continuous
Length
63 ft
3 main spans
Daily traffic
2,863
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 over Sep Local Road is a concrete continuous slab carrying I 15 over Sep Local Road in Beaverhead County, Montana. It was built in 1983, so it is 42 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 2,863 vehicles a day, roughly 23% of them trucks, projected to reach 3,120 by 2043. The structure is 63 ft (19.2 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 Local Road
Location2.5M S Dillon
RouteInterstate 15
CountyBeaverhead County
StateMontana
Coordinates45.18909, -112.6775
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.
Substructure7 GoodSome minor problems.
Last inspectionJanuary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating41 US tons
Inventory rating31 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length63 ft (19.2 m)
Longest span23 ft (7 m)
Deck width44 ft (13.5 m)
Roadway width41 ft (12.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,863 (2023)
Projected traffic3,120 by 2043
Trucks23%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesOther
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 Local Road built?

It was built in 1983, making it 42 years old in 2025.

What condition is I 15 over Sep Local Road 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 Local Road carry?

About 2,863 vehicles per day (2023 count), of which roughly 23% are trucks.

How long is I 15 over Sep Local Road?

The structure is 63 ft (19.2 m) long with a longest span of 23 ft (7 m) and a deck 44 ft wide.

Who owns I 15 over Sep Local Road?

It is owned by the State Highway Agency.