US Bridges

SR 18 over Soos Creek

Good

King County, Washington · 6.7 E JCT SR 164 · Structure no. 0014768B0000000

Built
1996
29 years old
Condition
Good
inspected March 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
124 ft
1 main span
Daily traffic
26,257
2023 count
Owner
State
State Highway Agency

About this bridge

SR 18 over Soos Creek is a prestressed concrete stringer/multi-beam or girder carrying SR 18 over Soos Creek in King County, Washington. It was built in 1996, so it is 29 years old, younger than the Washington average of 49.8 years.

The most recent inspection reported to the Federal Highway Administration rates it in good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 26,257 vehicles a day, roughly 14% of them trucks, projected to reach 37,992 by 2039. The structure is 124 ft (37.8 m) long and 41 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

CarriesSR 18
CrossesSoos Creek
Location6.7 E JCT SR 164
RouteState Highway 18
Coordinates47.35275, -122.12967
Functional classUrban Principal Arterial - Other Freeway or Expressway

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour within limits of footing or piles
Structural evaluation7: Better than present minimum criteria
Deck geometry6: Equal to present minimum criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating99 US tons
Inventory rating60 US tons

Structure

MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHS 25 or greater
Structure length124 ft (37.8 m)
Longest span119 ft (36.3 m)
Deck width41 ft (12.5 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic26,257 (2023)
Projected traffic37,992 by 2039
Trucks14%
Lanes on structure2
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed3.7 mi (6 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerState Highway Agency
Maintained byState Highway Agency
Historic statusHistorical significance not determinable at this time
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$2.4 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 18 over Soos Creek built?

It was built in 1996, making it 29 years old in 2025.

What condition is SR 18 over Soos Creek in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in March 2024.

How much traffic does SR 18 over Soos Creek carry?

About 26,257 vehicles per day (2023 count), of which roughly 14% are trucks.

How long is SR 18 over Soos Creek?

The structure is 124 ft (37.8 m) long with a longest span of 119 ft (36.3 m) and a deck 41 ft wide.

Who owns SR 18 over Soos Creek?

It is owned by the State Highway Agency.