US Bridges

SH 9 over Flat Creek

Fair

Latah County, Idaho · 9.1 Nw. Deary · Structure no. 000000000010290

Built
1959
66 years old
Condition
Fair
inspected July 2024
Type
Frame
Concrete
Length
23 ft
1 main span
Daily traffic
960
2023 count
Owner
State
State Highway Agency

About this bridge

SH 9 over Flat Creek is a concrete frame carrying SH 9 over Flat Creek in Latah County, Idaho. It was built in 1959, so it is 66 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 960 vehicles a day, roughly 23% of them trucks, projected to reach 1,440 by 2042. The structure is 23 ft (7 m) long and 34 ft wide. If it were closed, the detour would be 26.7 mi (43 km).

Location

Open in Google Maps
CarriesSH 9
CrossesFlat Creek
Location9.1 Nw. Deary
RouteState Highway 9
CountyLatah County
StateIdaho
Coordinates46.86469, -116.71653
Functional classRural Major Collector

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.
Superstructure7 GoodSome minor problems.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2024
Inspection intervalevery 48 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Waterway adequacy9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating56 US tons
Inventory rating33 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1
Design loadH 15
Structure length23 ft (7 m)
Longest span23 ft (7 m)
Deck width34 ft (10.4 m)
Roadway width29 ft (8.7 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic960 (2023)
Projected traffic1,440 by 2042
Trucks23%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed26.7 mi (43 km)
TollOn a free road
National Highway SystemNo

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 SH 9 over Flat Creek built?

It was built in 1959, making it 66 years old in 2025.

What condition is SH 9 over Flat 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 2024.

How much traffic does SH 9 over Flat Creek carry?

About 960 vehicles per day (2023 count), of which roughly 23% are trucks.

How long is SH 9 over Flat Creek?

The structure is 23 ft (7 m) long with a longest span of 23 ft (7 m) and a deck 34 ft wide.

Who owns SH 9 over Flat Creek?

It is owned by the State Highway Agency.