US Bridges

I 90 over Sep Eastside Road

Fair

Powell County, Montana · 0.6M S Deer Lodge · Structure no. I00090187+00291

Built
1961
64 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
168 ft
3 main spans
Daily traffic
4,371
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Sep Eastside Road is a prestressed concrete stringer/multi-beam or girder carrying I 90 over Sep Eastside Road in Powell County, Montana. It was built in 1961, so it is 64 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 4,371 vehicles a day, roughly 24% of them trucks, projected to reach 4,720 by 2043. The structure is 168 ft (51.2 m) long and 31 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

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CarriesI 90
CrossesSep Eastside Road
Location0.6M S Deer Lodge
RouteInterstate 90
CountyPowell County
StateMontana
Coordinates46.38307, -112.72577
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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionAugust 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50.9 US tons
Inventory rating36 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length168 ft (51.2 m)
Longest span61 ft (18.6 m)
Deck width31 ft (9.3 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,371 (2023)
Projected traffic4,720 by 2043
Trucks24%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed3.7 mi (6 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$456,000
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 90 over Sep Eastside Road built?

It was built in 1961, making it 64 years old in 2025.

What condition is I 90 over Sep Eastside 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 August 2023.

How much traffic does I 90 over Sep Eastside Road carry?

About 4,371 vehicles per day (2023 count), of which roughly 24% are trucks.

How long is I 90 over Sep Eastside Road?

The structure is 168 ft (51.2 m) long with a longest span of 61 ft (18.6 m) and a deck 31 ft wide.

Who owns I 90 over Sep Eastside Road?

It is owned by the State Highway Agency.