US Bridges

STC6868;TRAIL Crk over N. Fork Big Lost River

Fair

Custer County, Idaho · 18.9 N.E. Sun Valley · Structure no. 000000000033380

Built
1970
55 years old
Condition
Fair
inspected July 2024
Type
Slab
Wood or Timber
Length
32 ft
1 main span
Daily traffic
440
2023 count
Owner
Local
Other Local Agency

About this bridge

STC6868;TRAIL Crk over N. Fork Big Lost River is a wood or timber slab carrying STC6868;TRAIL Crk over N. Fork Big Lost River in Custer County, Idaho. It was built in 1970, so it is 55 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 440 vehicles a day, roughly 2% of them trucks, projected to reach 660 by 2042. The structure is 32 ft (9.8 m) long and 25 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesSTC6868;TRAIL Crk
CrossesN. Fork Big Lost River
Location18.9 N.E. Sun Valley
RouteCounty Highway 6868
CountyCuster County
StateIdaho
Coordinates43.91425, -114.13183
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 protection6 SatisfactoryStructural elements show some minor deterioration.
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 geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating49.1 US tons
Inventory rating34 US tons

Structure

Structure typeSlab
MaterialWood or Timber
DeckWood or timber
Main spans1
Design loadH 15
Structure length32 ft (9.8 m)
Longest span31 ft (9.4 m)
Deck width25 ft (7.5 m)
Roadway width23 ft (7.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic440 (2023)
Projected traffic660 by 2042
Trucks2%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerOther Local Agency
Maintained byOther Local Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$335,000 (2017 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was STC6868;TRAIL Crk over N. Fork Big Lost River built?

It was built in 1970, making it 55 years old in 2025.

What condition is STC6868;TRAIL Crk over N. Fork 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 STC6868;TRAIL Crk over N. Fork Big Lost River carry?

About 440 vehicles per day (2023 count), of which roughly 2% are trucks.

How long is STC6868;TRAIL Crk over N. Fork Big Lost River?

The structure is 32 ft (9.8 m) long with a longest span of 31 ft (9.4 m) and a deck 25 ft wide.

Who owns STC6868;TRAIL Crk over N. Fork Big Lost River?

It is owned by the Other Local Agency.