US Bridges

SR 599 over 42nd Ave S

Fair

King County, Washington · 0.7 N JCT I-5 · Structure no. 0008103B0000000

Built
1968
57 years old
Condition
Fair
inspected May 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
220 ft
3 main spans
Daily traffic
22,284
2023 count
Owner
State
State Highway Agency

About this bridge

SR 599 over 42nd Ave S is a prestressed concrete stringer/multi-beam or girder carrying SR 599 over 42nd Ave S in King County, Washington. It was built in 1968, so it is 57 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 22,284 vehicles a day, roughly 10% of them trucks, projected to reach 35,192 by 2039. The structure is 220 ft (67.1 m) long and 40 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesSR 599
Crosses42nd Ave S
Location0.7 N JCT I-5
RouteState Highway 599
CountyKing County
StateWashington
Coordinates47.48867, -122.28017
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 inspectionMay 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 rating63.9 US tons
Inventory rating38 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length220 ft (67.1 m)
Longest span100 ft (30.5 m)
Deck width40 ft (12.2 m)
Roadway width36 ft (11.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic22,284 (2023)
Projected traffic35,192 by 2039
Trucks10%
Lanes on structure2
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$4 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 599 over 42nd Ave S built?

It was built in 1968, making it 57 years old in 2025.

What condition is SR 599 over 42nd Ave S 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 2024.

How much traffic does SR 599 over 42nd Ave S carry?

About 22,284 vehicles per day (2023 count), of which roughly 10% are trucks.

How long is SR 599 over 42nd Ave S?

The structure is 220 ft (67.1 m) long with a longest span of 100 ft (30.5 m) and a deck 40 ft wide.

Who owns SR 599 over 42nd Ave S?

It is owned by the State Highway Agency.