US Bridges

Big Flat Road over Big Willow Creek

Fair

Payette County, Idaho · 7.2N 16.6E New Plymouth · Structure no. 000000000028355

Built
1970
55 years old
Condition
Fair
inspected September 2024
Type
Tee Beam
Prestressed Concrete
Length
31 ft
1 main span
Daily traffic
50
2023 count
Owner
County
County Highway Agency

About this bridge

Big Flat Road over Big Willow Creek is a prestressed concrete tee beam carrying Big Flat Road over Big Willow Creek in Payette County, Idaho. It was built in 1970, 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 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 50 vehicles a day, roughly 67% of them trucks, projected to reach 75 by 2042. The structure is 31 ft (9.4 m) long and 24 ft wide. If it were closed, the detour would be 98.8 mi (159 km).

Location

Open in Google Maps
CarriesBig Flat Road
CrossesBig Willow Creek
Location7.2N 16.6E New Plymouth
RouteCounty Highway 0
CountyPayette County
StateIdaho
Coordinates44.07492, -116.48528
Functional classRural Local

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.
Substructure5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2024
Inspection intervalevery 12 months
Operating statusOpen, no restriction
ScourUnknown foundation; not evaluated for scour
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 adequacy5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment5: Somewhat better than minimum adequacy to tolerate being left in place as is
Operating rating60.5 US tons
Inventory rating41.7 US tons

Structure

Structure typeTee Beam
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 20
Structure length31 ft (9.4 m)
Longest span29 ft (8.8 m)
Deck width24 ft (7.3 m)
Roadway width23 ft (7.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic50 (2023)
Projected traffic75 by 2042
Trucks67%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed98.8 mi (159 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$360,000 (2019 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Big Flat Road over Big Willow Creek built?

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

What condition is Big Flat Road over Big 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 September 2024.

How much traffic does Big Flat Road over Big Willow Creek carry?

About 50 vehicles per day (2023 count), of which roughly 67% are trucks.

How long is Big Flat Road over Big Willow Creek?

The structure is 31 ft (9.4 m) long with a longest span of 29 ft (8.8 m) and a deck 24 ft wide.

Who owns Big Flat Road over Big Willow Creek?

It is owned by the County Highway Agency.