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Spokane Street Viaduct Widening Project

Access Alternatives

Until there is once again westbound access to the Spokane Street Viaduct from surface streets in SODO, southbound vehicles approaching Spokane on First Ave S will be detoured to the low level swing bridge to get to West Seattle. To reduce the expected congestion on this bridge during construction, SDOT has requested that marine vessels voluntarily provide advance notification when they will require the swing bridge to open, enabling drivers to plan accordingly.

When SDOT receives advance notification of a bridge opening expected during afternoon peak travel time (3 p.m. to 7 p.m. on weekdays), this opening will be announced on the electronic messaging signs now operating at Terminal 5 and at Fourth and Spokane. SDOT staff will also send the message with a specific time, if available, using Twitter (sign up to receive the Twitter messages at The closure will also be posted on the Travelers Information Map on SDOT's website,

Alternative routes include:

South on 1st Ave S across the 1st Ave S Bridge, to W Marginal Way SW to West Seattle

South on 4th Ave S, left on S Michigan St to northbound I-5 to the West Seattle Bridge exit

1st Ave S or 4th Ave S north to Edgar Martinez ramp, to I-5 south to West Seattle exit, to S Spokane St Viaduct

For questions regarding how Metro Transit bus routes will be affected during this construction period, contact King County Metro Transit directly: by phone at (206) 553-3000; email at; or visit for route information. Specifically, riders of routes 15, 18, 21, 22, 56, 57, 118, 119 are most likely to be directly impacted. If you would like to receive King County Metro e-mail route alerts, you may sign-up for them at

Please note the primary detour route is a heavily used truck route serving industry in the Duwamish and the Port of Seattle's terminals. Many industrial and maritime businesses - and the thousands of jobs they support - depend on the corridor for the movement of goods.

Current Signed Detour route

The primary detour for vehicles approaching the construction zone will be signed. For through traffic heading westbound the route is:

  • NORTH on 6th Ave S
  • WEST on Lander
  • SOUTH on 1st Ave S,
  • SOUTH on E Marginal Way to return to the SPOKANE STREET lower roadway

Signals along these routes have been adjusted to reduce congestion, but greater congestion and slower transit times should be expected.

Pedestrian access on South Spokane Street and local business access will be maintained by the contractor.

Alternate routes for commuters from West Seattle into downtown include:

  • Exit Spokane Viaduct at new eastbound 4th Avenue S off-ramp
  • North on SR-99 to downtown exits at Seneca and Western Ave.
  • North on East Marginal Way S/Alaskan Way S to Atlantic, Royal Brougham, King, Main, or Yesler.
  • Stay on the Spokane Street Viaduct to I-5, then North on I-5 to downtown exits.

Alternate routes for commuters from West Seattle southbound include:

  • Exit Spokane Viaduct at new eastbound 4th Avenue S off-ramp
  • South on East Marginal Way to Michigan, east to I-5
  • South on East Marginal Way to First Avenue South Bridge, connect to I-509
  • South on East Marginal to Lucille, then east to First or Fourth Avenues or Airport Way, then north or south on any of those arterials

Alternate routes for commuters from downtown to West Seattle include:

  • North on First Avenue S to east on Edgar Martinez Drive S, onto SR519 to I-5 southbound
  • North on Fourth Avenue S to the SR519 on-ramp, north of Holgate, to I-5 southbound
  • North to First Avenue to Columbia Street, to SR99/Alaskan Way Viaduct southbound
  • South on Fourth Avenue S to east on S Michigan Street, to I-5 northbound I-5
  • South on First Avenue S across the First Avenue Bridge, to West Marginal Way SW exit north

Tools to help motorists get around during construction include the following:

Questions? Please contact:

Paul Elliott, SDOT Community Relations

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