US Bridges

SR 906 over Hyak Creek

FairPosted for load

Kittitas County, Washington · 1.7 E King CO · Structure no. 0001140B0000000

Built
1928
97 years old
Condition
Fair
inspected September 2024
Type
Arch - Deck
Concrete
Length
186 ft
1 main span
Daily traffic
823
2023 count
Owner
State
State Highway Agency

About this bridge

SR 906 over Hyak Creek is a concrete arch - deck carrying SR 906 over Hyak Creek in Kittitas County, Washington. It was built in 1928, so it is 97 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 6 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 823 vehicles a day, roughly 10% of them trucks, projected to reach 669 by 2039. The structure is 186 ft (56.7 m) long and 31 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesSR 906
CrossesHyak Creek
Location1.7 E King CO
RouteState Highway 906
CountyKittitas County
StateWashington
Coordinates47.40092, -121.40492
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
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Channel and channel protection6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionSeptember 2024
Inspection intervalevery 24 months
Operating statusPosted for load restriction
ScourFoundations on dry land well above flood water elevations
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 adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating29.3 US tons
Inventory rating22.5 US tons

Structure

Structure typeArch - Deck
MaterialConcrete
DeckConcrete, cast-in-place
Main spans1 (+3 approach)
Design loadH 20
Structure length186 ft (56.7 m)
Longest span90 ft (27.4 m)
Deck width31 ft (9.4 m)
Roadway width28 ft (8.5 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic823 (2023)
Projected traffic669 by 2039
Trucks10%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$3 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 906 over Hyak Creek built?

It was built in 1928, making it 97 years old in 2025.

What condition is SR 906 over Hyak 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 SR 906 over Hyak Creek carry?

About 823 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is SR 906 over Hyak Creek?

The structure is 186 ft (56.7 m) long with a longest span of 90 ft (27.4 m) and a deck 31 ft wide.

Who owns SR 906 over Hyak Creek?

It is owned by the State Highway Agency.