US Bridges

Mt HWY 91 over Beaverhead River

Fair

Beaverhead County, Montana · 3M SW Dillon · Structure no. S00222003+02951

Built
1945
80 years old, rebuilt 1994
Condition
Fair
inspected April 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
140 ft
3 main spans
Daily traffic
612
2023 count
Owner
State
State Highway Agency

About this bridge

Mt HWY 91 over Beaverhead River is a steel continuous stringer/multi-beam or girder carrying Mt HWY 91 over Beaverhead River in Beaverhead County, Montana. It was built in 1945 and reconstructed in 1994, so it is 80 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 612 vehicles a day, roughly 1% of them trucks, projected to reach 643 by 2043. The structure is 140 ft (42.6 m) long and 34 ft wide. If it were closed, the detour would be 6.8 mi (11 km).

Location

Open in Google Maps
CarriesMt HWY 91
CrossesBeaverhead River
Location3M SW Dillon
RouteState Highway 222
CountyBeaverhead County
StateMontana
Coordinates45.18167, -112.68898
Functional classRural Major Collector

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.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionApril 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 geometry6: Equal to present minimum criteria
Waterway adequacy7: Better than present minimum criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating53.6 US tons
Inventory rating41.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length140 ft (42.6 m)
Longest span54 ft (16.4 m)
Deck width34 ft (10.5 m)
Roadway width32 ft (9.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic612 (2023)
Projected traffic643 by 2043
Trucks1%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.8 mi (11 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—
NavigationNo navigation control on waterway

Frequently asked questions

When was Mt HWY 91 over Beaverhead River built?

It was built in 1945, making it 80 years old in 2025. It was reconstructed in 1994.

What condition is Mt HWY 91 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 April 2023.

How much traffic does Mt HWY 91 over Beaverhead River carry?

About 612 vehicles per day (2023 count), of which roughly 1% are trucks.

How long is Mt HWY 91 over Beaverhead River?

The structure is 140 ft (42.6 m) long with a longest span of 54 ft (16.4 m) and a deck 34 ft wide.

Who owns Mt HWY 91 over Beaverhead River?

It is owned by the State Highway Agency.