US Bridges

Kent-Blk Diam RD over Big Soos Creek

Fair

King County, Washington · 1.2 MI S of SR-18 · Structure no. 084814000000000

Built
1931
94 years old
Condition
Fair
inspected May 2023
Type
Frame
Concrete
Length
36 ft
2 main spans
Daily traffic
7,293
2018 count
Owner
County
County Highway Agency

About this bridge

Kent-Blk Diam RD over Big Soos Creek is a concrete frame carrying Kent-Blk Diam RD over Big Soos Creek in King County, Washington. It was built in 1931, so it is 94 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.

It carries about 7,293 vehicles a day, roughly 6% of them trucks, projected to reach 8,450 by 2038. The structure is 36 ft (11 m) long and 26 ft wide. If it were closed, the detour would be 3.1 mi (5 km).

Location

Open in Google Maps
CarriesKent-Blk Diam RD
CrossesBig Soos Creek
Location1.2 MI S of SR-18
RouteCounty Highway 93681
CountyKing County
StateWashington
Coordinates47.34357, -122.13439
Functional classUrban Minor Arterial

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 protection7 GoodSome minor problems.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourScour critical; foundations unstable for calculated scour conditions
Structural evaluation5: Somewhat better than minimum adequacy to tolerate being left in place as is
Deck geometry2: Basically intolerable, requiring high priority of replacement
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating30 US tons
Inventory rating23.3 US tons

Structure

Structure typeFrame
MaterialConcrete
DeckConcrete, cast-in-place
Main spans2
Design loadHS 15
Structure length36 ft (11 m)
Longest span17 ft (5.2 m)
Deck width26 ft (7.8 m)
Roadway width24 ft (7.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic7,293 (2018)
Projected traffic8,450 by 2038
Trucks6%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.1 mi (5 km)
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerCounty Highway Agency
Maintained byCounty Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$1.7 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was Kent-Blk Diam RD over Big Soos Creek built?

It was built in 1931, making it 94 years old in 2025.

What condition is Kent-Blk Diam RD over Big Soos 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 May 2023.

How much traffic does Kent-Blk Diam RD over Big Soos Creek carry?

About 7,293 vehicles per day (2018 count), of which roughly 6% are trucks.

How long is Kent-Blk Diam RD over Big Soos Creek?

The structure is 36 ft (11 m) long with a longest span of 17 ft (5.2 m) and a deck 26 ft wide.

Who owns Kent-Blk Diam RD over Big Soos Creek?

It is owned by the County Highway Agency.