US Bridges

SR 18 over Soos CR

Good

King County, Washington · 6.7 E JCT SR 164 · Structure no. 0006068D0000000

Built
1959
66 years old, rebuilt 1979
Condition
Good
inspected March 2024
Type
Slab
Concrete Continuous
Length
120 ft
3 main spans
Daily traffic
26,257
2023 count
Owner
State
State Highway Agency

About this bridge

SR 18 over Soos CR is a concrete continuous slab carrying SR 18 over Soos CR in King County, Washington. It was built in 1959 and reconstructed in 1979, so it is 66 years old, older 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 120 ft (36.6 m) long and 46 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesSR 18
CrossesSoos CR
Location6.7 E JCT SR 164
RouteState Highway 18
CountyKing County
StateWashington
Coordinates47.35289, -122.12992
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 above top of footing
Structural evaluation7: Better than present minimum criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating56 US tons
Inventory rating33 US tons

Structure

Structure typeSlab
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length120 ft (36.6 m)
Longest span47 ft (14.3 m)
Deck width46 ft (13.9 m)
Roadway width44 ft (13.4 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$2.6 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 18 over Soos CR built?

It was built in 1959, making it 66 years old in 2025. It was reconstructed in 1979.

What condition is SR 18 over Soos CR 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 CR carry?

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

How long is SR 18 over Soos CR?

The structure is 120 ft (36.6 m) long with a longest span of 47 ft (14.3 m) and a deck 46 ft wide.

Who owns SR 18 over Soos CR?

It is owned by the State Highway Agency.