US Bridges

IRR - S 39 over RR

Fair

Rosebud County, Montana · 16M NW Colstrip · Structure no. P00039038+07711

Built
1983
42 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
393 ft
2 main spans
Daily traffic
787
2023 count
Owner
State
State Highway Agency

About this bridge

IRR - S 39 over RR is a steel stringer/multi-beam or girder carrying IRR - S 39 over RR in Rosebud County, Montana. It was built in 1983, so it is 42 years old, younger 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 787 vehicles a day, roughly 8% of them trucks, projected to reach 826 by 2043. The structure is 393 ft (119.8 m) long and 42 ft wide. If it were closed, the detour would be 123.7 mi (199 km).

Location

Open in Google Maps
CarriesIRR - S 39
CrossesRR
Location16M NW Colstrip
RouteState Highway 39
CountyRosebud County
StateMontana
Coordinates46.08964, -106.74597
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionAugust 2023
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 geometry7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating30 US tons
Inventory rating23 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans2 (+2 approach)
Design loadHS 20
Structure length393 ft (119.8 m)
Longest span100 ft (30.5 m)
Deck width42 ft (12.9 m)
Roadway width39 ft (12 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic787 (2023)
Projected traffic826 by 2043
Trucks8%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesRailroad
Detour if closed123.7 mi (199 km)
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 RR built?

It was built in 1983, making it 42 years old in 2025.

What condition is IRR - S 39 over RR 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 IRR - S 39 over RR carry?

About 787 vehicles per day (2023 count), of which roughly 8% are trucks.

How long is IRR - S 39 over RR?

The structure is 393 ft (119.8 m) long with a longest span of 100 ft (30.5 m) and a deck 42 ft wide.

Who owns IRR - S 39 over RR?

It is owned by the State Highway Agency.