US Bridges

5th Ave S over Clark Fork 085

Fair

Sanders County, Montana · 1M SW Plains · Structure no. L45139000+02001

Built
1975
50 years old
Condition
Fair
inspected August 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
980 ft
7 main spans
Daily traffic
100
2025 count
Owner
County
County Highway Agency

About this bridge

5th Ave S over Clark Fork 085 is a steel continuous stringer/multi-beam or girder carrying 5th Ave S over Clark Fork 085 in Sanders County, Montana. It was built in 1975, so it is 50 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 100 vehicles a day, roughly 3% of them trucks, projected to reach 100 by 2040. The structure is 980 ft (298.6 m) long and 28 ft wide. If it were closed, the detour would be 23 mi (37 km).

Location

Open in Google Maps
Carries5th Ave S
CrossesClark Fork 085
Location1M SW Plains
RouteCounty Highway 45151
CountySanders County
StateMontana
Coordinates47.45458, -114.89354
Functional classRural Minor 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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
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 geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating48 US tons
Inventory rating37 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans7
Design loadHS 20
Structure length980 ft (298.6 m)
Longest span148 ft (45.1 m)
Deck width28 ft (8.5 m)
Roadway width26 ft (7.9 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 closed23 mi (37 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty 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 5th Ave S over Clark Fork 085 built?

It was built in 1975, making it 50 years old in 2025.

What condition is 5th Ave S over Clark Fork 085 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 5th Ave S over Clark Fork 085 carry?

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

How long is 5th Ave S over Clark Fork 085?

The structure is 980 ft (298.6 m) long with a longest span of 148 ft (45.1 m) and a deck 28 ft wide.

Who owns 5th Ave S over Clark Fork 085?

It is owned by the County Highway Agency.