US Bridges

US 20 over Willow Creek

Fair

Bonneville County, Idaho · 3 N. Idaho Falls · Structure no. 000000000012375

Built
1970
55 years old, rebuilt 2004
Condition
Fair
inspected April 2022
Type
Frame
Concrete
Length
22 ft
1 main span
Daily traffic
27,000
2023 count
Owner
State
State Highway Agency

About this bridge

US 20 over Willow Creek is a concrete frame carrying US 20 over Willow Creek in Bonneville County, Idaho. It was built in 1970 and reconstructed in 2004, so it is 55 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 27,000 vehicles a day, roughly 9% of them trucks, projected to reach 40,500 by 2042. The structure is 22 ft (6.7 m) long and 219 ft wide. If it were closed, the detour would be 6.2 mi (10 km).

Location

Open in Google Maps
CarriesUS 20
CrossesWillow Creek
Location3 N. Idaho Falls
RouteU.S. Route 20
CountyBonneville County
StateIdaho
Coordinates43.54742, -111.9995
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.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection7 GoodSome minor problems.
Last inspectionApril 2022
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating74 US tons
Inventory rating44 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length22 ft (6.7 m)
Longest span22 ft (6.7 m)
Deck width219 ft (66.8 m)
Roadway width219 ft (66.8 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic27,000 (2023)
Projected traffic40,500 by 2042
Trucks9%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed6.2 mi (10 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—
NavigationNo navigation control on waterway

Frequently asked questions

When was US 20 over Willow Creek built?

It was built in 1970, making it 55 years old in 2025. It was reconstructed in 2004.

What condition is US 20 over Willow 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 April 2022.

How much traffic does US 20 over Willow Creek carry?

About 27,000 vehicles per day (2023 count), of which roughly 9% are trucks.

How long is US 20 over Willow Creek?

The structure is 22 ft (6.7 m) long with a longest span of 22 ft (6.7 m) and a deck 219 ft wide.

Who owns US 20 over Willow Creek?

It is owned by the State Highway Agency.