US Bridges

US 12 over Clwater R.;nprr;arrow Br

Fair

Nez Perce County, Idaho · 10.4 E. Lewiston · Structure no. 000000000010390

Built
1972
53 years old
Condition
Fair
inspected October 2023
Type
Stringer/Multi-beam or Girder
Steel Continuous
Length
1,248 ft
8 main spans
Daily traffic
4,900
2023 count
Owner
State
State Highway Agency

About this bridge

US 12 over Clwater R.;nprr;arrow Br is a steel continuous stringer/multi-beam or girder carrying US 12 over Clwater R.;nprr;arrow Br in Nez Perce County, Idaho. It was built in 1972, so it is 53 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.

It carries about 4,900 vehicles a day, roughly 13% of them trucks, projected to reach 7,350 by 2042. The structure is 1,248 ft (380.4 m) long and 44 ft wide. If it were closed, the detour would be 36 mi (58 km).

Location

Open in Google Maps
CarriesUS 12
CrossesClwater R.;nprr;arrow Br
Location10.4 E. Lewiston
RouteU.S. Route 12
CountyNez Perce County
StateIdaho
Coordinates46.47156, -116.77336
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection7 GoodSome minor problems.
Last inspectionOctober 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 geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating41 US tons
Inventory rating24 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialSteel Continuous
DeckConcrete, cast-in-place
Main spans8
Design loadHS 20
Structure length1,248 ft (380.4 m)
Longest span250 ft (76.2 m)
Deck width44 ft (13.4 m)
Roadway width41 ft (12.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,900 (2023)
Projected traffic7,350 by 2042
Trucks13%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesRailroad and waterway
Detour if closed36 mi (58 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$14.9 million (2023 estimate)
NavigationNavigation control on waterway (bridge permit required)

Frequently asked questions

When was US 12 over Clwater R.;nprr;arrow Br built?

It was built in 1972, making it 53 years old in 2025.

What condition is US 12 over Clwater R.;nprr;arrow 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 October 2023.

How much traffic does US 12 over Clwater R.;nprr;arrow Br carry?

About 4,900 vehicles per day (2023 count), of which roughly 13% are trucks.

How long is US 12 over Clwater R.;nprr;arrow Br?

The structure is 1,248 ft (380.4 m) long with a longest span of 250 ft (76.2 m) and a deck 44 ft wide.

Who owns US 12 over Clwater R.;nprr;arrow Br?

It is owned by the State Highway Agency.