US Bridges

S 41 over Beaverhead River

Fair

Madison County, Montana · 12M SW Twin Bridges · Structure no. P00049014+06711

Built
1949
76 years old
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
153 ft
2 main spans
Daily traffic
2,403
2023 count
Owner
State
State Highway Agency

About this bridge

S 41 over Beaverhead River is a steel stringer/multi-beam or girder carrying S 41 over Beaverhead River in Madison County, Montana. It was built in 1949, so it is 76 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 5 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 2,403 vehicles a day, roughly 12% of them trucks, projected to reach 2,559 by 2043. The structure is 153 ft (46.6 m) long and 32 ft wide. If it were closed, the detour would be 119.9 mi (193 km).

Location

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CarriesS 41
CrossesBeaverhead River
Location12M SW Twin Bridges
RouteState Highway 41
CountyMadison County
StateMontana
Coordinates45.38337, -112.4532
Functional classRural Principal Arterial - Other

Condition and inspection

Fair

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

ComponentRatingMeaning
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionMay 2024
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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating35.1 US tons
Inventory rating27 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans2
Design loadH 15
Structure length153 ft (46.6 m)
Longest span74 ft (22.7 m)
Deck width32 ft (9.7 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,403 (2023)
Projected traffic2,559 by 2043
Trucks12%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed119.9 mi (193 km)
TollOn a free road
National Highway SystemYes

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—
NavigationNo navigation control on waterway

Frequently asked questions

When was S 41 over Beaverhead River built?

It was built in 1949, making it 76 years old in 2025.

What condition is S 41 over Beaverhead River 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 May 2024.

How much traffic does S 41 over Beaverhead River carry?

About 2,403 vehicles per day (2023 count), of which roughly 12% are trucks.

How long is S 41 over Beaverhead River?

The structure is 153 ft (46.6 m) long with a longest span of 74 ft (22.7 m) and a deck 32 ft wide.

Who owns S 41 over Beaverhead River?

It is owned by the State Highway Agency.