US Bridges

Stc 6749; 3300W over Big Lost River

Fair

Butte County, Idaho · 1.5 N. 2.3 W. Arco · Structure no. 000000000031510

Built
1926
99 years old
Condition
Fair
inspected July 2023
Type
Tee Beam
Concrete
Length
36 ft
1 main span
Daily traffic
290
2023 count
Owner
County
County Highway Agency

About this bridge

Stc 6749; 3300W over Big Lost River is a concrete tee beam carrying Stc 6749; 3300W over Big Lost River in Butte County, Idaho. It was built in 1926, so it is 99 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 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 290 vehicles a day, roughly 21% of them trucks, projected to reach 435 by 2042. The structure is 36 ft (11 m) long and 26 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesStc 6749; 3300W
CrossesBig Lost River
Location1.5 N. 2.3 W. Arco
RouteCounty Highway 6749
CountyButte County
StateIdaho
Coordinates43.65867, -113.35619
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment7: Better than present minimum criteria
Operating rating50 US tons
Inventory rating30 US tons

Structure

Structure typeTee Beam
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length36 ft (11 m)
Longest span35 ft (10.7 m)
Deck width26 ft (7.9 m)
Roadway width23 ft (7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic290 (2023)
Projected traffic435 by 2042
Trucks21%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 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$431,000 (2023 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Stc 6749; 3300W over Big Lost River built?

It was built in 1926, making it 99 years old in 2025.

What condition is Stc 6749; 3300W 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 2023.

How much traffic does Stc 6749; 3300W over Big Lost River carry?

About 290 vehicles per day (2023 count), of which roughly 21% are trucks.

How long is Stc 6749; 3300W over Big Lost River?

The structure is 36 ft (11 m) long with a longest span of 35 ft (10.7 m) and a deck 26 ft wide.

Who owns Stc 6749; 3300W over Big Lost River?

It is owned by the County Highway Agency.