US Bridges

Forest Road 470 over Selway R Swiftwater

FairPosted for load

Idaho County, Idaho · 3 Mi. from Lowell Id · Structure no. 011707000000087

Built
1936
89 years old, rebuilt 1984
Condition
Fair
inspected June 2024
Type
Truss - Thru
Steel
Length
385 ft
2 main spans
Daily traffic
50
Owner
Federal
U.S. Forest Service

About this bridge

Forest Road 470 over Selway R Swiftwater is a steel truss - thru carrying Forest Road 470 over Selway R Swiftwater in Idaho County, Idaho. It was built in 1936 and reconstructed in 1984, so it is 89 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. Its operating status is: posted for load restriction.

It carries about 50 vehicles a day, projected to reach 75 by 2045. The structure is 385 ft (117.3 m) long and 13 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

Open in Google Maps
CarriesForest Road 470
CrossesSelway R Swiftwater
Location3 Mi. from Lowell Id
RouteFederal Lands Road 470
CountyIdaho County
StateIdaho
Coordinates46.11523, -115.57208
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
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJune 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation4: Meets minimum tolerable limits to be left in place as is
Deck geometry4: Meets minimum tolerable limits to be left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating22.2 US tons
Inventory rating16.4 US tons

Structure

Structure typeTruss - Thru
MaterialSteel
DeckWood or timber
Main spans2 (+2 approach)
Design loadH 15
Structure length385 ft (117.3 m)
Longest span150 ft (45.7 m)
Deck width13 ft (4.1 m)
Roadway width12 ft (3.7 m)
Vertical clearance over deck14 ft (4.3 m)

Traffic and service

Average daily traffic50 (—)
Projected traffic75 by 2045
Trucks—
Lanes on structure1
Traffic directionOne-lane bridge for two-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.2 mi (158 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerU.S. Forest Service
Maintained byU.S. Forest Service
Historic statusHistorical significance not determinable at this time
Work proposedNone recorded
Estimated improvement cost—
NavigationNo navigation control on waterway

Frequently asked questions

When was Forest Road 470 over Selway R Swiftwater built?

It was built in 1936, making it 89 years old in 2025. It was reconstructed in 1984.

What condition is Forest Road 470 over Selway R Swiftwater 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 June 2024.

How much traffic does Forest Road 470 over Selway R Swiftwater carry?

About 50 vehicles per day (latest count).

How long is Forest Road 470 over Selway R Swiftwater?

The structure is 385 ft (117.3 m) long with a longest span of 150 ft (45.7 m) and a deck 13 ft wide.

Who owns Forest Road 470 over Selway R Swiftwater?

It is owned by the U.S. Forest Service.