US Bridges

24th Ave S over SR 518 Ramps

Fair

King County, Washington · 1.5 E JCT SR 509 · Structure no. 0008644C0000000

Built
1970
55 years old
Condition
Fair
inspected March 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
363 ft
4 main spans
Daily traffic
2,564
2000 count
Owner
State
State Highway Agency

About this bridge

24th Ave S over SR 518 Ramps is a prestressed concrete continuous stringer/multi-beam or girder carrying 24th Ave S over SR 518 Ramps in King County, Washington. It was built in 1970, so it is 55 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 2,564 vehicles a day, roughly 5% of them trucks, projected to reach 5,144 by 2032. The structure is 363 ft (110.6 m) long and 40 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
Carries24th Ave S
CrossesSR 518 Ramps
Location1.5 E JCT SR 509
RouteCounty Highway 0
CountyKing County
StateWashington
Coordinates47.46593, -122.30239
Functional classUrban Collector

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry5: Somewhat better than minimum adequacy to tolerate being left in place as is
Approach roadway alignment8: Equal to present desirable criteria
Operating rating58 US tons
Inventory rating34 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans4
Design loadHS 20
Structure length363 ft (110.6 m)
Longest span117 ft (35.7 m)
Deck width40 ft (12.3 m)
Roadway width38 ft (11.6 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic2,564 (2000)
Projected traffic5,144 by 2032
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemNo

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$7.2 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was 24th Ave S over SR 518 Ramps built?

It was built in 1970, making it 55 years old in 2025.

What condition is 24th Ave S over SR 518 Ramps 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 March 2024.

How much traffic does 24th Ave S over SR 518 Ramps carry?

About 2,564 vehicles per day (2000 count), of which roughly 5% are trucks.

How long is 24th Ave S over SR 518 Ramps?

The structure is 363 ft (110.6 m) long with a longest span of 117 ft (35.7 m) and a deck 40 ft wide.

Who owns 24th Ave S over SR 518 Ramps?

It is owned by the State Highway Agency.