US Bridges

I 90 over Sep S 56th ST W

Fair

Yellowstone County, Montana · 5.6M W Billings · Structure no. I00090440+02532

Built
1961
64 years old, rebuilt 2023
Condition
Fair
inspected October 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
153 ft
3 main spans
Daily traffic
12,397
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Sep S 56th ST W is a prestressed concrete stringer/multi-beam or girder carrying I 90 over Sep S 56th ST W in Yellowstone County, Montana. It was built in 1961 and reconstructed in 2023, 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 12,397 vehicles a day, roughly 10% of them trucks, projected to reach 13,016 by 2043. The structure is 153 ft (46.6 m) long and 31 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI 90
CrossesSep S 56th ST W
Location5.6M W Billings
RouteInterstate 90
CountyYellowstone County
StateMontana
Coordinates45.70549, -108.65865
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 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 rating56.8 US tons
Inventory rating27.4 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length153 ft (46.6 m)
Longest span62 ft (18.9 m)
Deck width31 ft (9.6 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic12,397 (2023)
Projected traffic13,016 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$431,000
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 90 over Sep S 56th ST W built?

It was built in 1961, making it 64 years old in 2025. It was reconstructed in 2023.

What condition is I 90 over Sep S 56th ST W 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 October 2023.

How much traffic does I 90 over Sep S 56th ST W carry?

About 12,397 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is I 90 over Sep S 56th ST W?

The structure is 153 ft (46.6 m) long with a longest span of 62 ft (18.9 m) and a deck 31 ft wide.

Who owns I 90 over Sep S 56th ST W?

It is owned by the State Highway Agency.