US Bridges

US 20 over Rock Creek

Fair

Blaine County, Idaho · 20.7 E. Fairfield · Structure no. 000000000034435

Built
2019
6 years old
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Concrete
Length
159 ft
1 main span
Daily traffic
2,200
2023 count
Owner
State
State Highway Agency

About this bridge

US 20 over Rock Creek is a concrete stringer/multi-beam or girder carrying US 20 over Rock Creek in Blaine County, Idaho. It was built in 2019, so it is 6 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 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 2,200 vehicles a day, roughly 11% of them trucks, projected to reach 3,300 by 2042. The structure is 159 ft (48.5 m) long and 44 ft wide. If it were closed, the detour would be 60.3 mi (97 km).

Location

Open in Google Maps
CarriesUS 20
CrossesRock Creek
Location20.7 E. Fairfield
RouteU.S. Route 20
CountyBlaine County
StateIdaho
Coordinates43.3345, -114.38136
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.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection9 ExcellentNo problems noted.
Last inspectionJuly 2023
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating52.5 US tons
Inventory rating39.2 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadHL 93
Structure length159 ft (48.5 m)
Longest span157 ft (47.9 m)
Deck width44 ft (13.4 m)
Roadway width41 ft (12.4 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,200 (2023)
Projected traffic3,300 by 2042
Trucks11%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed60.3 mi (97 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 Rock Creek built?

It was built in 2019, making it 6 years old in 2025.

What condition is US 20 over Rock 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 July 2023.

How much traffic does US 20 over Rock Creek carry?

About 2,200 vehicles per day (2023 count), of which roughly 11% are trucks.

How long is US 20 over Rock Creek?

The structure is 159 ft (48.5 m) long with a longest span of 157 ft (47.9 m) and a deck 44 ft wide.

Who owns US 20 over Rock Creek?

It is owned by the State Highway Agency.