US Bridges

I 15 over RR

Fair

Toole County, Montana · 1M N Sunburst · Structure no. I00015390+01712

Built
1961
64 years old
Condition
Fair
inspected June 2023
Type
Stringer/Multi-beam or Girder
Steel
Length
313 ft
2 main spans
Daily traffic
955
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 over RR is a steel stringer/multi-beam or girder carrying I 15 over RR in Toole County, Montana. It was built in 1961, 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 955 vehicles a day, roughly 40% of them trucks, projected to reach 1,003 by 2043. The structure is 313 ft (95.4 m) long and 30 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 15
CrossesRR
Location1M N Sunburst
RouteInterstate 15
CountyToole County
StateMontana
Coordinates48.88901, -111.90772
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionJune 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Approach roadway alignment7: Better than present minimum criteria
Operating rating44 US tons
Inventory rating34 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans2 (+4 approach)
Design loadHS 20
Structure length313 ft (95.4 m)
Longest span54 ft (16.5 m)
Deck width30 ft (9 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic955 (2023)
Projected traffic1,003 by 2043
Trucks40%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesRailroad
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$887,000
NavigationNot applicable (no waterway)

Frequently asked questions

When was I 15 over RR built?

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

What condition is I 15 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 June 2023.

How much traffic does I 15 over RR carry?

About 955 vehicles per day (2023 count), of which roughly 40% are trucks.

How long is I 15 over RR?

The structure is 313 ft (95.4 m) long with a longest span of 54 ft (16.5 m) and a deck 30 ft wide.

Who owns I 15 over RR?

It is owned by the State Highway Agency.