US Bridges

US 12 over Clearwater R.(kamiah Br)

Fair

Lewis County, Idaho · In Kamiah · Structure no. 000000000010426

Built
1998
27 years old
Condition
Fair
inspected February 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
672 ft
7 main spans
Daily traffic
4,700
2023 count
Owner
State
State Highway Agency

About this bridge

US 12 over Clearwater R.(kamiah Br) is a prestressed concrete stringer/multi-beam or girder carrying US 12 over Clearwater R.(kamiah Br) in Lewis County, Idaho. It was built in 1998, so it is 27 years old, younger 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 4,700 vehicles a day, roughly 9% of them trucks, projected to reach 7,050 by 2042. The structure is 672 ft (204.8 m) long and 48 ft wide. If it were closed, the detour would be 77.1 mi (124 km).

Location

Open in Google Maps
CarriesUS 12
CrossesClearwater R.(kamiah Br)
LocationIn Kamiah
RouteU.S. Route 12
CountyLewis County
StateIdaho
Coordinates46.23029, -116.01872
Functional classRural Principal Arterial - Other

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 protection8 Very GoodNo problems noted.
Last inspectionFebruary 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating96 US tons
Inventory rating51 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans7
Design loadHS 25 or greater
Structure length672 ft (204.8 m)
Longest span119 ft (36.3 m)
Deck width48 ft (14.6 m)
Roadway width36 ft (10.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,700 (2023)
Projected traffic7,050 by 2042
Trucks9%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesWaterway
Detour if closed77.1 mi (124 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$11.3 million (2020 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was US 12 over Clearwater R.(kamiah Br) built?

It was built in 1998, making it 27 years old in 2025.

What condition is US 12 over Clearwater R.(kamiah Br) 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 February 2023.

How much traffic does US 12 over Clearwater R.(kamiah Br) carry?

About 4,700 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is US 12 over Clearwater R.(kamiah Br)?

The structure is 672 ft (204.8 m) long with a longest span of 119 ft (36.3 m) and a deck 48 ft wide.

Who owns US 12 over Clearwater R.(kamiah Br)?

It is owned by the State Highway Agency.