US Bridges

S Jackson ST over ST Tunnel

Fair

King County, Washington · S Jackson ST Wo 5th Ave S · Structure no. 085786000000000

Built
1987
38 years old
Condition
Fair
inspected July 2023
Type
Stringer/Multi-beam or Girder
Prestressed Concrete
Length
146 ft
1 main span
Daily traffic
26,700
2018 count
Owner
City
City or Municipal Highway Agency

About this bridge

S Jackson ST over ST Tunnel is a prestressed concrete stringer/multi-beam or girder carrying S Jackson ST over ST Tunnel in King County, Washington. It was built in 1987, so it is 38 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 26,700 vehicles a day, roughly 10% of them trucks, projected to reach 30,000 by 2043. The structure is 146 ft (44.5 m) long and 90 ft wide. If it were closed, the detour would be 1.2 mi (2 km).

Location

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CarriesS Jackson ST
CrossesST Tunnel
LocationS Jackson ST Wo 5th Ave S
RouteCity Street 1140
CountyKing County
StateWashington
Coordinates47.59917, -122.32833
Functional classUrban Other Principal 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.
Superstructure7 GoodSome minor problems.
Substructure7 GoodSome minor problems.
Last inspectionJuly 2023
Inspection intervalevery 24 months
Operating statusOpen, no restriction
ScourBridge not over waterway
Structural evaluation7: Better than present minimum criteria
Deck geometry2: Basically intolerable, requiring high priority of replacement
Approach roadway alignment8: Equal to present desirable criteria
Operating rating66 US tons
Inventory rating39 US tons

Structure

Structure typeStringer/Multi-beam or Girder
MaterialPrestressed Concrete
DeckConcrete, cast-in-place
Main spans1 (+2 approach)
Design loadHS 20
Structure length146 ft (44.5 m)
Longest span103 ft (31.4 m)
Deck width90 ft (27.4 m)
Roadway width56 ft (17.1 m)
Vertical clearance over deckUnrestricted

Traffic and service

Average daily traffic26,700 (2018)
Projected traffic30,000 by 2043
Trucks10%
Lanes on structure5
Traffic directionTwo-way traffic
CarriesHighway and pedestrian
CrossesRailroad
Detour if closed1.2 mi (2 km)
TollOn a free road
National Highway SystemYes

Ownership and planned work

OwnerCity or Municipal Highway Agency
Maintained byCity or Municipal Highway Agency
Historic statusNot eligible for the National Register of Historic Places
Work proposedReplacement because of substandard load-carrying capacity or roadway geometry
Estimated improvement cost$13.1 million
NavigationNot applicable (no waterway)

Frequently asked questions

When was S Jackson ST over ST Tunnel built?

It was built in 1987, making it 38 years old in 2025.

What condition is S Jackson ST 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 S Jackson ST over ST Tunnel carry?

About 26,700 vehicles per day (2018 count), of which roughly 10% are trucks.

How long is S Jackson ST over ST Tunnel?

The structure is 146 ft (44.5 m) long with a longest span of 103 ft (31.4 m) and a deck 90 ft wide.

Who owns S Jackson ST over ST Tunnel?

It is owned by the City or Municipal Highway Agency.