US Bridges

SR 18 over Peasley Canyon RD

Fair

King County, Washington · 1.9 E JCT I-5 · Structure no. 0005433A0000000

Built
1958
67 years old, rebuilt 2004
Condition
Fair
inspected May 2023
Type
Box Beam or Girders - Multiple
Concrete Continuous
Length
364 ft
3 main spans
Daily traffic
52,049
2023 count
Owner
State
State Highway Agency

About this bridge

SR 18 over Peasley Canyon RD is a concrete continuous box beam or girders - multiple carrying SR 18 over Peasley Canyon RD in King County, Washington. It was built in 1958 and reconstructed in 2004, so it is 67 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.

It carries about 52,049 vehicles a day, roughly 11% of them trucks, projected to reach 75,167 by 2039. The structure is 364 ft (111 m) long and 81 ft wide. If it were closed, the detour would be 3.7 mi (6 km).

Location

Open in Google Maps
CarriesSR 18
CrossesPeasley Canyon RD
Location1.9 E JCT I-5
RouteState Highway 18
CountyKing County
StateWashington
Coordinates47.30358, -122.27386
Functional classUrban Principal Arterial - Other Freeway or Expressway

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.
Last inspectionMay 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating50 US tons
Inventory rating30 US tons

Structure

Structure typeBox Beam or Girders - Multiple
MaterialConcrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20
Structure length364 ft (111 m)
Longest span140 ft (42.7 m)
Deck width81 ft (24.8 m)
Roadway width78 ft (23.9 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic52,049 (2023)
Projected traffic75,167 by 2039
Trucks11%
Lanes on structure5
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
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 statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$14.2 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 18 over Peasley Canyon RD built?

It was built in 1958, making it 67 years old in 2025. It was reconstructed in 2004.

What condition is SR 18 over Peasley Canyon RD 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 SR 18 over Peasley Canyon RD carry?

About 52,049 vehicles per day (2023 count), of which roughly 11% are trucks.

How long is SR 18 over Peasley Canyon RD?

The structure is 364 ft (111 m) long with a longest span of 140 ft (42.7 m) and a deck 81 ft wide.

Who owns SR 18 over Peasley Canyon RD?

It is owned by the State Highway Agency.