US Bridges

2900 West over Big Lost River

Fair

Butte County, Idaho · 3.5 S. 1.2 E. Arco · Structure no. 000000000031515

Built
1978
47 years old, rebuilt 2019
Condition
Fair
inspected July 2024
Type
Girder and Floorbeam System
Steel
Length
57 ft
1 main span
Daily traffic
50
2023 count
Owner
County
County Highway Agency

About this bridge

2900 West over Big Lost River is a steel girder and floorbeam system carrying 2900 West over Big Lost River in Butte County, Idaho. It was built in 1978 and reconstructed in 2019, so it is 47 years old, older than the Idaho average of 45.3 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 50 vehicles a day, roughly 20% of them trucks, projected to reach 75 by 2039. The structure is 57 ft (17.4 m) long and 22 ft wide. If it were closed, the detour would be 0.6 mi (1 km).

Location

Open in Google Maps
Carries2900 West
CrossesBig Lost River
Location3.5 S. 1.2 E. Arco
RouteCounty Highway 0
CountyButte County
StateIdaho
Coordinates43.58636, -113.27686
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
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 alignment6: Equal to present minimum criteria
Operating rating55 US tons
Inventory rating33 US tons

Structure

Structure typeGirder and Floorbeam System
MaterialSteel
DeckCorrugated steel
Main spans1
Design loadH 15
Structure length57 ft (17.4 m)
Longest span54 ft (16.5 m)
Deck width22 ft (6.8 m)
Roadway width22 ft (6.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (2023)
Projected traffic75 by 2039
Trucks20%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed0.6 mi (1 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$554,000 (2018 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was 2900 West over Big Lost River built?

It was built in 1978, making it 47 years old in 2025. It was reconstructed in 2019.

What condition is 2900 West over Big Lost 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 July 2024.

How much traffic does 2900 West over Big Lost River carry?

About 50 vehicles per day (2023 count), of which roughly 20% are trucks.

How long is 2900 West over Big Lost River?

The structure is 57 ft (17.4 m) long with a longest span of 54 ft (16.5 m) and a deck 22 ft wide.

Who owns 2900 West over Big Lost River?

It is owned by the County Highway Agency.