US Bridges

I 90 over Sep Heeb Road

Fair

Gallatin County, Montana · 2.5M E Manhattan · Structure no. I00090291+06371

Built
1965
60 years old, rebuilt 2022
Condition
Fair
inspected April 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
115 ft
3 main spans
Daily traffic
9,726
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Sep Heeb Road is a prestressed concrete stringer/multi-beam or girder carrying I 90 over Sep Heeb Road in Gallatin County, Montana. It was built in 1965 and reconstructed in 2022, so it is 60 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 9,726 vehicles a day, roughly 12% of them trucks, projected to reach 10,990 by 2043. The structure is 115 ft (35.1 m) long and 39 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 90
CrossesSep Heeb Road
Location2.5M E Manhattan
RouteInterstate 90
CountyGallatin County
StateMontana
Coordinates45.83059, -111.28516
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 inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating53 US tons
Inventory rating41 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length115 ft (35.1 m)
Longest span41 ft (12.6 m)
Deck width39 ft (12 m)
Roadway width36 ft (11.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic9,726 (2023)
Projected traffic10,990 by 2043
Trucks12%
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 over Sep Heeb Road built?

It was built in 1965, making it 60 years old in 2025. It was reconstructed in 2022.

What condition is I 90 over Sep Heeb 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 April 2024.

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

About 9,726 vehicles per day (2023 count), of which roughly 12% are trucks.

How long is I 90 over Sep Heeb Road?

The structure is 115 ft (35.1 m) long with a longest span of 41 ft (12.6 m) and a deck 39 ft wide.

Who owns I 90 over Sep Heeb Road?

It is owned by the State Highway Agency.