US Bridges

I 90 EB over Sep Southside Road

Fair

Mineral County, Montana · 6.2M E St. Regis · Structure no. I00090039+09911

Built
1984
41 years old
Condition
Fair
inspected November 2023
Type
Slab
Concrete Continuous
Length
78 ft
3 main spans
Daily traffic
3,559
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 EB over Sep Southside Road is a concrete continuous slab carrying I 90 EB over Sep Southside Road in Mineral County, Montana. It was built in 1984, so it is 41 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 3,559 vehicles a day, roughly 28% of them trucks, projected to reach 3,736 by 2043. The structure is 78 ft (23.8 m) long and 45 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 90 EB
CrossesSep Southside Road
Location6.2M E St. Regis
RouteInterstate 90
CountyMineral County
StateMontana
Coordinates47.23152, -115.01554
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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionNovember 2023
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 rating44 US tons
Inventory rating34 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length78 ft (23.8 m)
Longest span30 ft (9.1 m)
Deck width45 ft (13.7 m)
Roadway width41 ft (12.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,559 (2023)
Projected traffic3,736 by 2043
Trucks28%
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 90 EB over Sep Southside Road built?

It was built in 1984, making it 41 years old in 2025.

What condition is I 90 EB over Sep Southside 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 November 2023.

How much traffic does I 90 EB over Sep Southside Road carry?

About 3,559 vehicles per day (2023 count), of which roughly 28% are trucks.

How long is I 90 EB over Sep Southside Road?

The structure is 78 ft (23.8 m) long with a longest span of 30 ft (9.1 m) and a deck 45 ft wide.

Who owns I 90 EB over Sep Southside Road?

It is owned by the State Highway Agency.