US Bridges

I 15 Frontage RD over Beaverhead R-Int Ramp

Fair

Beaverhead County, Montana · 8M N Clark Canyon Dam · Structure no. I00015052+06323

Built
1988
37 years old
Condition
Fair
inspected December 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
104 ft
2 main spans
Daily traffic
100
2025 count
Owner
State
State Highway Agency

About this bridge

I 15 Frontage RD over Beaverhead R-Int Ramp is a prestressed concrete stringer/multi-beam or girder carrying I 15 Frontage RD over Beaverhead R-Int Ramp in Beaverhead County, Montana. It was built in 1988, so it is 37 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 100 vehicles a day, roughly 3% of them trucks, projected to reach 100 by 2040. The structure is 104 ft (31.7 m) long and 30 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesI 15 Frontage RD
CrossesBeaverhead R-Int Ramp
Location8M N Clark Canyon Dam
RouteInterstate 1301
CountyBeaverhead County
StateMontana
Coordinates45.0979, -112.77736
Functional classRural Local

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionDecember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating61 US tons
Inventory rating39 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 20
Structure length104 ft (31.7 m)
Longest span51 ft (15.5 m)
Deck width30 ft (9.2 m)
Roadway width27 ft (8.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic100 (2025)
Projected traffic100 by 2040
Trucks3%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed1.2 mi (2 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 proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$254,000
NavigationNo navigation control on waterway

Frequently asked questions

When was I 15 Frontage RD over Beaverhead R-Int Ramp built?

It was built in 1988, making it 37 years old in 2025.

What condition is I 15 Frontage RD over Beaverhead R-Int Ramp 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 December 2023.

How much traffic does I 15 Frontage RD over Beaverhead R-Int Ramp carry?

About 100 vehicles per day (2025 count), of which roughly 3% are trucks.

How long is I 15 Frontage RD over Beaverhead R-Int Ramp?

The structure is 104 ft (31.7 m) long with a longest span of 51 ft (15.5 m) and a deck 30 ft wide.

Who owns I 15 Frontage RD over Beaverhead R-Int Ramp?

It is owned by the State Highway Agency.