US Bridges

SR 18 over Lake Creek

Good

King County, Washington · 12.0 E JCT SR 169 · Structure no. 0019572C0000000

Built
2023
2 years old
Condition
Good
inspected December 2023
Type
Slab
Prestressed Concrete
Length
54 ft
1 main span
Daily traffic
12,687
2023 count
Owner
State
State Highway Agency

About this bridge

SR 18 over Lake Creek is a prestressed concrete slab carrying SR 18 over Lake Creek in King County, Washington. It was built in 2023, so it is 2 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 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 12,687 vehicles a day, roughly 17% of them trucks, projected to reach 19,020 by 2039. The structure is 54 ft (16.5 m) long and 73 ft wide. If it were closed, the detour would be 24.9 mi (40 km).

Location

Open in Google Maps
CarriesSR 18
CrossesLake Creek
Location12.0 E JCT SR 169
RouteState Highway 18
CountyKing County
StateWashington
Coordinates47.50405, -121.88464
Functional classRural Principal Arterial - Other

Condition and inspection

Good

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

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Channel and channel protection8 Very GoodNo problems noted.
Last inspectionDecember 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourFoundations stable; scour above top of footing
Structural evaluation8: Equal to present desirable criteria
Deck geometry9: Superior to present desirable criteria
Waterway adequacy8: Equal to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating81.5 US tons
Inventory rating62.8 US tons

Structure

Structure typeSlab
MaterialPrestressed Concrete
DeckConcrete, precast panels
Main spans1
Design loadHL 93
Structure length54 ft (16.5 m)
Longest span45 ft (13.7 m)
Deck width73 ft (22.3 m)
Roadway width70 ft (21.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic12,687 (2023)
Projected traffic19,020 by 2039
Trucks17%
Lanes on structure4
Traffic directionOne-way traffic
CarriesHighway
CrossesWaterway
Detour if closed24.9 mi (40 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$1.8 million (2022 estimate)
NavigationNo navigation control on waterway

Frequently asked questions

When was SR 18 over Lake Creek built?

It was built in 2023, making it 2 years old in 2025.

What condition is SR 18 over Lake 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 December 2023.

How much traffic does SR 18 over Lake Creek carry?

About 12,687 vehicles per day (2023 count), of which roughly 17% are trucks.

How long is SR 18 over Lake Creek?

The structure is 54 ft (16.5 m) long with a longest span of 45 ft (13.7 m) and a deck 73 ft wide.

Who owns SR 18 over Lake Creek?

It is owned by the State Highway Agency.