US Bridges

28th to 24th Ave S over Terrain (future SR 509)

Good

King County, Washington · 0.3 MI W of SR-99 · Structure no. 002005160000000

Built
2017
8 years old
Condition
Good
inspected April 2024
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
129 ft
1 main span
Daily traffic
4,000
2017 count
Owner
State
State Highway Agency

About this bridge

28th to 24th Ave S over Terrain (future SR 509) is a prestressed concrete stringer/multi-beam or girder carrying 28th to 24th Ave S over Terrain (future SR 509) in King County, Washington. It was built in 2017, so it is 8 years old, younger 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 8 out of 9. All primary components (deck, superstructure, substructure, or culvert) are rated 7 or higher. No significant problems were noted.

It carries about 4,000 vehicles a day, projected to reach 6,550 by 2037. The structure is 129 ft (39.3 m) long and 87 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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Carries28th to 24th Ave S
CrossesTerrain (future SR 509)
Location0.3 MI W of SR-99
RouteCity Street 0
CountyKing County
StateWashington
Coordinates47.41933, -122.30108
Functional classUrban Minor Arterial

Condition and inspection

Good

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

ComponentRatingMeaning
Deck8 Very GoodNo problems noted.
Superstructure8 Very GoodNo problems noted.
Substructure8 Very GoodNo problems noted.
Last inspectionApril 2024
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation8: Equal to present desirable 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 rating64.6 US tons
Inventory rating47.8 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1
Design loadHL 93
Structure length129 ft (39.3 m)
Longest span123 ft (37.5 m)
Deck width87 ft (26.5 m)
Roadway width60 ft (18.3 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic4,000 (2017)
Projected traffic6,550 by 2037
Trucks0%
Lanes on structure4
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesOther
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 statusHistorical significance not determinable at this time
Work proposedReplacement because of relocation of road
Estimated improvement cost$8.2 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was 28th to 24th Ave S over Terrain (future SR 509) built?

It was built in 2017, making it 8 years old in 2025.

What condition is 28th to 24th Ave S over Terrain (future SR 509) 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 April 2024.

How much traffic does 28th to 24th Ave S over Terrain (future SR 509) carry?

About 4,000 vehicles per day (2017 count).

How long is 28th to 24th Ave S over Terrain (future SR 509)?

The structure is 129 ft (39.3 m) long with a longest span of 123 ft (37.5 m) and a deck 87 ft wide.

Who owns 28th to 24th Ave S over Terrain (future SR 509)?

It is owned by the State Highway Agency.