US Bridges

STC4710;GRAVES Crk over Salmon River

Fair

Idaho County, Idaho · 9.4 S. 2.9 W. Cottonwood · Structure no. 000000000029385

Built
1973
52 years old
Condition
Fair
inspected September 2024
Type
Stringer/Multi-beam or Girder
Steel
Length
400 ft
4 main spans
Daily traffic
30
2023 count
Owner
Local
Other Local Agency

About this bridge

STC4710;GRAVES Crk over Salmon River is a steel stringer/multi-beam or girder carrying STC4710;GRAVES Crk over Salmon River in Idaho County, Idaho. It was built in 1973, so it is 52 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 30 vehicles a day, roughly 50% of them trucks, projected to reach 45 by 2042. The structure is 400 ft (121.9 m) long and 21 ft wide. If it were closed, the detour would be 29.8 mi (48 km).

Location

Open in Google Maps
CarriesSTC4710;GRAVES Crk
CrossesSalmon River
Location9.4 S. 2.9 W. Cottonwood
RouteCounty Highway 4710
CountyIdaho County
StateIdaho
Coordinates45.91133, -116.4115
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 protection8 Very GoodNo problems noted.
Last inspectionSeptember 2024
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 geometry3: Basically intolerable, requiring high priority of corrective action
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment6: Equal to present minimum criteria
Operating rating110.1 US tons
Inventory rating105.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length400 ft (121.9 m)
Longest span152 ft (46.3 m)
Deck width21 ft (6.4 m)
Roadway width16 ft (4.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic30 (2023)
Projected traffic45 by 2042
Trucks50%
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed29.8 mi (48 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 proposedNone recorded
Estimated improvement cost—
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was STC4710;GRAVES Crk over Salmon River built?

It was built in 1973, making it 52 years old in 2025.

What condition is STC4710;GRAVES Crk over Salmon 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 September 2024.

How much traffic does STC4710;GRAVES Crk over Salmon River carry?

About 30 vehicles per day (2023 count), of which roughly 50% are trucks.

How long is STC4710;GRAVES Crk over Salmon River?

The structure is 400 ft (121.9 m) long with a longest span of 152 ft (46.3 m) and a deck 21 ft wide.

Who owns STC4710;GRAVES Crk over Salmon River?

It is owned by the Other Local Agency.