US Bridges

I 15 NB over Abandoned RR

Fair

Jefferson County, Montana · 0.6M S Montana City · Structure no. I00015187+00791

Built
1969
56 years old
Condition
Fair
inspected October 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
238 ft
5 main spans
Daily traffic
3,787
2023 count
Owner
State
State Highway Agency

About this bridge

I 15 NB over Abandoned RR is a prestressed concrete stringer/multi-beam or girder carrying I 15 NB over Abandoned RR in Jefferson County, Montana. It was built in 1969, so it is 56 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 3,787 vehicles a day, roughly 10% of them trucks, projected to reach 3,976 by 2043. The structure is 238 ft (72.5 m) long and 41 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesI 15 NB
CrossesAbandoned RR
Location0.6M S Montana City
RouteInterstate 15
CountyJefferson County
StateMontana
Coordinates46.53199, -111.94087
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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionOctober 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating57 US tons
Inventory rating44 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans5
Design loadHS 20
Structure length238 ft (72.5 m)
Longest span66 ft (20.1 m)
Deck width41 ft (12.6 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic3,787 (2023)
Projected traffic3,976 by 2043
Trucks10%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesOther
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 15 NB over Abandoned RR built?

It was built in 1969, making it 56 years old in 2025.

What condition is I 15 NB over Abandoned 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 October 2023.

How much traffic does I 15 NB over Abandoned RR carry?

About 3,787 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is I 15 NB over Abandoned RR?

The structure is 238 ft (72.5 m) long with a longest span of 66 ft (20.1 m) and a deck 41 ft wide.

Who owns I 15 NB over Abandoned RR?

It is owned by the State Highway Agency.