US Bridges

IRR - S 39 over Int Colstrip I 94

Fair

Rosebud County, Montana · 6M W Forsyth · Structure no. P00039051+02161

Built
1967
58 years old
Condition
Fair
inspected February 2025
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
248 ft
5 main spans
Daily traffic
833
2023 count
Owner
State
State Highway Agency

About this bridge

IRR - S 39 over Int Colstrip I 94 is a prestressed concrete stringer/multi-beam or girder carrying IRR - S 39 over Int Colstrip I 94 in Rosebud County, Montana. It was built in 1967, so it is 58 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 833 vehicles a day, roughly 7% of them trucks, projected to reach 875 by 2043. The structure is 248 ft (75.7 m) long and 33 ft wide.

Location

Open in Google Maps
CarriesIRR - S 39
CrossesInt Colstrip I 94
Location6M W Forsyth
RouteState Highway 39
CountyRosebud County
StateMontana
Coordinates46.24994, -106.81615
Functional classRural Minor Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionFebruary 2025
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating40 US tons
Inventory rating23 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans5
Design loadHS 20
Structure length248 ft (75.7 m)
Longest span65 ft (19.8 m)
Deck width33 ft (10.1 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic833 (2023)
Projected traffic875 by 2043
Trucks7%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesOverpass structure at an interchange
CrossesHighway
Detour if closed—
TollOn a free road
National Highway SystemNo

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 IRR - S 39 over Int Colstrip I 94 built?

It was built in 1967, making it 58 years old in 2025.

What condition is IRR - S 39 over Int Colstrip I 94 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 February 2025.

How much traffic does IRR - S 39 over Int Colstrip I 94 carry?

About 833 vehicles per day (2023 count), of which roughly 7% are trucks.

How long is IRR - S 39 over Int Colstrip I 94?

The structure is 248 ft (75.7 m) long with a longest span of 65 ft (19.8 m) and a deck 33 ft wide.

Who owns IRR - S 39 over Int Colstrip I 94?

It is owned by the State Highway Agency.