US Bridges

SR 520 over 124 Ave NE - NW Ramp

Fair

King County, Washington · 0.6 E JCT I-405 · Structure no. 0009086C0000000

Built
1971
54 years old, rebuilt 1998
Condition
Fair
inspected January 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
255 ft
3 main spans
Daily traffic
45,466
2023 count
Owner
State
State Highway Agency

About this bridge

SR 520 over 124 Ave NE - NW Ramp is a prestressed concrete continuous stringer/multi-beam or girder carrying SR 520 over 124 Ave NE - NW Ramp in King County, Washington. It was built in 1971 and reconstructed in 1998, so it is 54 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 45,466 vehicles a day, roughly 3% of them trucks, projected to reach 74,202 by 2039. The structure is 255 ft (77.7 m) long and 59 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesSR 520
Crosses124 Ave NE - NW Ramp
Location0.6 E JCT I-405
RouteState Highway 520
CountyKing County
StateWashington
Coordinates47.63131, -122.17617
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
Deck7 GoodSome minor problems.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure7 GoodSome minor problems.
Last inspectionJanuary 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation3: Basically intolerable, requiring high priority of corrective action
Deck geometry6: Equal to present minimum criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating20.7 US tons
Inventory rating16.1 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length255 ft (77.7 m)
Longest span92 ft (28 m)
Deck width59 ft (18 m)
Roadway width56 ft (17.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic45,466 (2023)
Projected traffic74,202 by 2039
Trucks3%
Lanes on structure3
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed1.2 mi (2 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$7 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 520 over 124 Ave NE - NW Ramp built?

It was built in 1971, making it 54 years old in 2025. It was reconstructed in 1998.

What condition is SR 520 over 124 Ave NE - NW Ramp 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 January 2024.

How much traffic does SR 520 over 124 Ave NE - NW Ramp carry?

About 45,466 vehicles per day (2023 count), of which roughly 3% are trucks.

How long is SR 520 over 124 Ave NE - NW Ramp?

The structure is 255 ft (77.7 m) long with a longest span of 92 ft (28 m) and a deck 59 ft wide.

Who owns SR 520 over 124 Ave NE - NW Ramp?

It is owned by the State Highway Agency.