US Bridges

SR 520 W-N Ramp over Northup Way

Fair

King County, Washington · JCT I-405 · Structure no. 0014039F0000000

Built
1993
32 years old
Condition
Fair
inspected October 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete Continuous
Length
162 ft
3 main spans
Daily traffic
12,471
2023 count
Owner
State
State Highway Agency

About this bridge

SR 520 W-N Ramp over Northup Way is a prestressed concrete continuous stringer/multi-beam or girder carrying SR 520 W-N Ramp over Northup Way in King County, Washington. It was built in 1993, so it is 32 years old, younger 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 12,471 vehicles a day, roughly 5% of them trucks, projected to reach 19,598 by 2039. The structure is 162 ft (49.4 m) long and 35 ft wide.

Location

Open in Google Maps
CarriesSR 520 W-N Ramp
CrossesNorthup Way
LocationJCT I-405
RouteState Highway 520
CountyKing County
StateWashington
Coordinates47.63317, -122.18697
Functional classUrban Principal Arterial - Interstate

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 inspectionOctober 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation6: Equal to present minimum criteria
Deck geometry9: Superior to present desirable criteria
Approach roadway alignment8: Equal to present desirable criteria
Operating rating80 US tons
Inventory rating48 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete Continuous
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length162 ft (49.4 m)
Longest span64 ft (19.5 m)
Deck width35 ft (10.7 m)
Roadway width27 ft (8.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic12,471 (2023)
Projected traffic19,598 by 2039
Trucks5%
Lanes on structure1
Traffic directionOne-way traffic
CarriesHighway
CrossesHighway
Detour if closed—
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$2.5 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 520 W-N Ramp over Northup Way built?

It was built in 1993, making it 32 years old in 2025.

What condition is SR 520 W-N Ramp over Northup Way 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 October 2024.

How much traffic does SR 520 W-N Ramp over Northup Way carry?

About 12,471 vehicles per day (2023 count), of which roughly 5% are trucks.

How long is SR 520 W-N Ramp over Northup Way?

The structure is 162 ft (49.4 m) long with a longest span of 64 ft (19.5 m) and a deck 35 ft wide.

Who owns SR 520 W-N Ramp over Northup Way?

It is owned by the State Highway Agency.