US Bridges

I 90 over Int W Garrison-Rr

Poor

Powell County, Montana · Garrison · Structure no. I00090174+03631

Built
1979
46 years old
Condition
Poor
inspected July 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
710 ft
7 main spans
Daily traffic
5,232
2023 count
Owner
State
State Highway Agency

About this bridge

I 90 over Int W Garrison-Rr is a prestressed concrete stringer/multi-beam or girder carrying I 90 over Int W Garrison-Rr in Powell County, Montana. It was built in 1979, so it is 46 years old, younger than the Montana average of 47 years.

The most recent inspection reported to the Federal Highway Administration rates it in poor condition with a lowest component rating of 4 out of 9. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

It carries about 5,232 vehicles a day, roughly 20% of them trucks, projected to reach 5,650 by 2043. The structure is 710 ft (216.3 m) long and 45 ft wide.

Location

Open in Google Maps
CarriesI 90
CrossesInt W Garrison-Rr
LocationGarrison
RouteInterstate 90
CountyPowell County
StateMontana
Coordinates46.52248, -112.80964
Functional classRural Principal Arterial - Interstate

Condition and inspection

Poor

The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure4 PoorAdvanced section loss, deterioration, spalling or scour.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating58 US tons
Inventory rating37 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans7
Design loadHS 20
Structure length710 ft (216.3 m)
Longest span107 ft (32.6 m)
Deck width45 ft (13.6 m)
Roadway width42 ft (12.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic5,232 (2023)
Projected traffic5,650 by 2043
Trucks20%
Lanes on structure2
Traffic directionOne-way traffic
CarriesOverpass structure at an interchange
CrossesHighway and railroad
Detour if closed—
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 Int W Garrison-Rr built?

It was built in 1979, making it 46 years old in 2025.

What condition is I 90 over Int W Garrison-Rr in?

The National Bridge Inventory rates it in poor condition. The lowest-rated primary component is rated 4 or below, indicating advanced deterioration. Poor does not mean unsafe; such bridges are inspected more often and may carry load restrictions. The last reported inspection was in July 2023.

How much traffic does I 90 over Int W Garrison-Rr carry?

About 5,232 vehicles per day (2023 count), of which roughly 20% are trucks.

How long is I 90 over Int W Garrison-Rr?

The structure is 710 ft (216.3 m) long with a longest span of 107 ft (32.6 m) and a deck 45 ft wide.

Who owns I 90 over Int W Garrison-Rr?

It is owned by the State Highway Agency.