US Bridges

S 43 over Big Hole River

Fair

Deer Lodge County, Montana · 16M NE Wisdom · Structure no. P00046041+08581

Built
1960
65 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
235 ft
4 main spans
Daily traffic
353
2023 count
Owner
State
State Highway Agency

About this bridge

S 43 over Big Hole River is a prestressed concrete stringer/multi-beam or girder carrying S 43 over Big Hole River in Deer Lodge County, Montana. It was built in 1960, so it is 65 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 353 vehicles a day, roughly 9% of them trucks, projected to reach 371 by 2043. The structure is 235 ft (71.5 m) long and 31 ft wide. If it were closed, the detour would be 85.1 mi (137 km).

Location

Open in Google Maps
CarriesS 43
CrossesBig Hole River
Location16M NE Wisdom
RouteState Highway 43
CountyDeer Lodge County
StateMontana
Coordinates45.80762, -113.31331
Functional classRural Minor Arterial

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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionAugust 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 geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating44 US tons
Inventory rating25 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length235 ft (71.5 m)
Longest span61 ft (18.5 m)
Deck width31 ft (9.6 m)
Roadway width27 ft (8.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic353 (2023)
Projected traffic371 by 2043
Trucks9%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed85.1 mi (137 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 S 43 over Big Hole River built?

It was built in 1960, making it 65 years old in 2025.

What condition is S 43 over Big Hole 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 August 2023.

How much traffic does S 43 over Big Hole River carry?

About 353 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is S 43 over Big Hole River?

The structure is 235 ft (71.5 m) long with a longest span of 61 ft (18.5 m) and a deck 31 ft wide.

Who owns S 43 over Big Hole River?

It is owned by the State Highway Agency.