US Bridges

Forest Road 309 over So. Fk. Clearwater River

Fair

Idaho County, Idaho · 19 Mi. from Grangeville · Structure no. 011704000001004

Built
1962
63 years old
Condition
Fair
inspected August 2022
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
139 ft
1 main span
Daily traffic
40
Owner
Federal
U.S. Forest Service

About this bridge

Forest Road 309 over So. Fk. Clearwater River is a prestressed concrete stringer/multi-beam or girder carrying Forest Road 309 over So. Fk. Clearwater River in Idaho County, Idaho. It was built in 1962, so it is 63 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 40 vehicles a day, projected to reach 60 by 2045. The structure is 139 ft (42.4 m) long and 30 ft wide. If it were closed, the detour would be 98.2 mi (158 km).

Location

Open in Google Maps
CarriesForest Road 309
CrossesSo. Fk. Clearwater River
Location19 Mi. from Grangeville
RouteFederal Lands Road 309
CountyIdaho County
StateIdaho
Coordinates45.83021, -115.93245
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.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionAugust 2022
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment3: Basically intolerable, requiring high priority of corrective action
Operating rating36.4 US tons
Inventory rating28.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1 (+2 approach)
Design loadHS 20
Structure length139 ft (42.4 m)
Longest span70 ft (21.3 m)
Deck width30 ft (9 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic40 (—)
Projected traffic60 by 2045
Trucks—
Lanes on structure2
Traffic directionTwo-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 309 over So. Fk. Clearwater River built?

It was built in 1962, making it 63 years old in 2025.

What condition is Forest Road 309 over So. Fk. Clearwater 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 August 2022.

How much traffic does Forest Road 309 over So. Fk. Clearwater River carry?

About 40 vehicles per day (latest count).

How long is Forest Road 309 over So. Fk. Clearwater River?

The structure is 139 ft (42.4 m) long with a longest span of 70 ft (21.3 m) and a deck 30 ft wide.

Who owns Forest Road 309 over So. Fk. Clearwater River?

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