US Bridges

I 15 over Sep Lump Gulch Road

Fair

Jefferson County, Montana · 0.6M N Clancy · Structure no. I00015182+07381

Built
1969
56 years old
Condition
Fair
inspected March 2024
Type
Slab
Concrete Continuous
Length
80 ft
3 main spans
Daily traffic
3,787
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 over Sep Lump Gulch Road is a concrete continuous slab carrying I 15 over Sep Lump Gulch Road in Jefferson County, Montana. It was built in 1969, so it is 56 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 3,787 vehicles a day, roughly 10% of them trucks, projected to reach 3,976 by 2043. The structure is 80 ft (24.4 m) long and 41 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 15
CrossesSep Lump Gulch Road
Location0.6M N Clancy
RouteInterstate 15
CountyJefferson County
StateMontana
Coordinates46.47702, -111.97797
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMarch 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 geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating36 US tons
Inventory rating28 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length80 ft (24.4 m)
Longest span31 ft (9.3 m)
Deck width41 ft (12.4 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,787 (2023)
Projected traffic3,976 by 2043
Trucks10%
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 Lump Gulch Road built?

It was built in 1969, making it 56 years old in 2025.

What condition is I 15 over Sep Lump Gulch 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 March 2024.

How much traffic does I 15 over Sep Lump Gulch Road carry?

About 3,787 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is I 15 over Sep Lump Gulch Road?

The structure is 80 ft (24.4 m) long with a longest span of 31 ft (9.3 m) and a deck 41 ft wide.

Who owns I 15 over Sep Lump Gulch Road?

It is owned by the State Highway Agency.