US Bridges

5th Ave S over ST Tunnel

Fair

King County, Washington · 5th Ave S So S Jackson ST · Structure no. 085053000000000

Built
1910
115 years old, rebuilt 1987
Condition
Fair
inspected July 2023
Type
Slab
Concrete
Length
940 ft
38 main spans
Daily traffic
8,000
2020 count
Owner
Local
Other Local Agency

About this bridge

5th Ave S over ST Tunnel is a concrete slab carrying 5th Ave S over ST Tunnel in King County, Washington. It was built in 1910 and reconstructed in 1987, so it is 115 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 8,000 vehicles a day, roughly 5% of them trucks, projected to reach 9,000 by 2043. The structure is 940 ft (286.5 m) long and 16 ft wide.

Location

Open in Google Maps
Carries5th Ave S
CrossesST Tunnel
Location5th Ave S So S Jackson ST
RouteCity Street 1140
CountyKing County
StateWashington
Coordinates47.59778, -122.32778
Functional classUrban Minor Arterial

Condition and inspection

Fair

The lowest-rated primary component is rated 5 or 6. Minor deterioration is present but the structure is sound.

ComponentRatingMeaning
Deck6 SatisfactoryStructural elements show some minor deterioration.
Superstructure6 SatisfactoryStructural elements show some minor deterioration.
Substructure6 SatisfactoryStructural elements show some minor deterioration.
Last inspectionJuly 2023
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 rating54 US tons
Inventory rating32 US tons

Structure

Structure typeSlab
MaterialConcrete
DeckConcrete, cast-in-place
Main spans38
Design loadUnknown
Structure length940 ft (286.5 m)
Longest span30 ft (9.1 m)
Deck width16 ft (4.9 m)
Roadway width40 ft (12.2 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic8,000 (2020)
Projected traffic9,000 by 2043
Trucks5%
Lanes on structure2
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesOther
Detour if closed—
TollOn a free road
National Highway SystemNo

Ownership and planned work

OwnerOther Local Agency
Maintained byOther Local Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedRehabilitation because of general structure deterioration or inadequate strength
Estimated improvement cost$18.8 million (2022 estimate)
NavigationNot applicable (no waterway)

Frequently asked questions

When was 5th Ave S over ST Tunnel built?

It was built in 1910, making it 115 years old in 2025. It was reconstructed in 1987.

What condition is 5th Ave S over ST Tunnel 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 July 2023.

How much traffic does 5th Ave S over ST Tunnel carry?

About 8,000 vehicles per day (2020 count), of which roughly 5% are trucks.

How long is 5th Ave S over ST Tunnel?

The structure is 940 ft (286.5 m) long with a longest span of 30 ft (9.1 m) and a deck 16 ft wide.

Who owns 5th Ave S over ST Tunnel?

It is owned by the Other Local Agency.