US Bridges

Old State HWY/3150 over Imbler Creek

FairPosted for load

Whitman County, Washington · 0.12 MI SE SR 23 · Structure no. 082298000000000

Built
1946
79 years old
Condition
Fair
inspected December 2023
Type
Slab
Concrete Continuous
Length
56 ft
3 main spans
Daily traffic
40
2021 count
Owner
County
County Highway Agency

About this bridge

Old State HWY/3150 over Imbler Creek is a concrete continuous slab carrying Old State HWY/3150 over Imbler Creek in Whitman County, Washington. It was built in 1946, so it is 79 years old, older than the Washington average of 49.8 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. Its operating status is: posted for load restriction.

It carries about 40 vehicles a day, roughly 25% of them trucks, projected to reach 41 by 2044. The structure is 56 ft (17.1 m) long and 30 ft wide. If it were closed, the detour would be 8.1 mi (13 km).

Location

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CarriesOld State HWY/3150
CrossesImbler Creek
Location0.12 MI SE SR 23
RouteCounty Highway 31500
CountyWhitman County
StateWashington
Coordinates47.13408, -117.82787
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
Deck5 FairAll primary structural elements are sound but may have minor section loss, cracking, spalling or scour.
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 inspectionDecember 2023
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourUnknown foundation; not evaluated for scour
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating23.6 US tons
Inventory rating18.2 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 15
Structure length56 ft (17.1 m)
Longest span21 ft (6.4 m)
Deck width30 ft (9.1 m)
Roadway width26 ft (7.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic40 (2021)
Projected traffic41 by 2044
Trucks25%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed8.1 mi (13 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$2.4 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Old State HWY/3150 over Imbler Creek built?

It was built in 1946, making it 79 years old in 2025.

What condition is Old State HWY/3150 over Imbler 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 December 2023.

How much traffic does Old State HWY/3150 over Imbler Creek carry?

About 40 vehicles per day (2021 count), of which roughly 25% are trucks.

How long is Old State HWY/3150 over Imbler Creek?

The structure is 56 ft (17.1 m) long with a longest span of 21 ft (6.4 m) and a deck 30 ft wide.

Who owns Old State HWY/3150 over Imbler Creek?

It is owned by the County Highway Agency.