US Bridges

SR 599 over 42nd Ave S / Macadam RD

Good

King County, Washington · 0.7 N JCT I-5 · Structure no. 0008103A0000000

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

About this bridge

SR 599 over 42nd Ave S / Macadam RD is a prestressed concrete stringer/multi-beam or girder carrying SR 599 over 42nd Ave S / Macadam RD 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 good condition with a lowest component rating of 7 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 22,284 vehicles a day, roughly 10% of them trucks, projected to reach 35,192 by 2039. The structure is 234 ft (71.3 m) long and 40 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

Open in Google Maps
CarriesSR 599
Crosses42nd Ave S / Macadam RD
Location0.7 N JCT I-5
RouteState Highway 599
CountyKing County
StateWashington
Coordinates47.48892, -122.28011
Functional classUrban Principal Arterial - Other Freeway or Expressway

Condition and inspection

Good

All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

ComponentRatingMeaning
Deck7 GoodSome minor problems.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionMarch 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than 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 rating67 US tons
Inventory rating39 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans3
Design loadHS 20 + Mod
Structure length234 ft (71.3 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$4.4 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was SR 599 over 42nd Ave S / Macadam RD built?

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

What condition is SR 599 over 42nd Ave S / Macadam RD in?

The National Bridge Inventory rates it in good condition. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted. The last reported inspection was in March 2024.

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

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

How long is SR 599 over 42nd Ave S / Macadam RD?

The structure is 234 ft (71.3 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 / Macadam RD?

It is owned by the State Highway Agency.