US Bridges

US 20 over Silver Creek

Fair

Blaine County, Idaho · 8.9 W. Carey · Structure no. 000000000015100

Built
1979
46 years old
Condition
Fair
inspected May 2023
Type
Box Beam or Girders - Multiple
Prestressed Concrete
Length
103 ft
3 main spans
Daily traffic
2,000
2023 count
Owner
State
State Highway Agency

About this bridge

US 20 over Silver Creek is a prestressed concrete box beam or girders - multiple carrying US 20 over Silver Creek in Blaine County, Idaho. It was built in 1979, so it is 46 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 2,000 vehicles a day, roughly 20% of them trucks, projected to reach 3,000 by 2042. The structure is 103 ft (31.4 m) long and 40 ft wide. If it were closed, the detour would be 83.9 mi (135 km).

Location

Open in Google Maps
CarriesUS 20
CrossesSilver Creek
Location8.9 W. Carey
RouteU.S. Route 20
CountyBlaine County
StateIdaho
Coordinates43.31736, -114.10561
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Substructure7 GoodSome minor problems.
Channel and channel protection7 GoodSome minor problems.
Last inspectionMay 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 rating86 US tons
Inventory rating38 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length103 ft (31.4 m)
Longest span35 ft (10.7 m)
Deck width40 ft (12.2 m)
Roadway width37 ft (11.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,000 (2023)
Projected traffic3,000 by 2042
Trucks20%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed83.9 mi (135 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 proposedNone recorded
Estimated improvement cost$1.3 million (2019 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was US 20 over Silver Creek built?

It was built in 1979, making it 46 years old in 2025.

What condition is US 20 over Silver Creek 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 May 2023.

How much traffic does US 20 over Silver Creek carry?

About 2,000 vehicles per day (2023 count), of which roughly 20% are trucks.

How long is US 20 over Silver Creek?

The structure is 103 ft (31.4 m) long with a longest span of 35 ft (10.7 m) and a deck 40 ft wide.

Who owns US 20 over Silver Creek?

It is owned by the State Highway Agency.