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Puget Sound Transportation Projects

Downtown Seattle Transit Tunnel (Seattle Bus Tunnel)

Map of Seattle Bus Tunnel Stations

The Downtown Seattle Transit Tunnel (DSTT) was built in the 1980's as the Seattle Bus Tunnel. It was seen as an innovative way to route buses from the outskirts of the city into and through downtown. The opening of the tunnel moved about 40% of rush-hour buses off of the congested downtown streets. Buses from here access the Eastside via I-90 and SR 520, Sea-Tac airport and Northgate. Stations in the tunnel access major downtown locations and employers. An extension to the tunnel, the Metro Busway, was added later. The busway allows buses their own right-of-way extending South from the city center.

Tunnel stations allow access to major shopping and employment centers in the city's central core:

  • Convention Center (serves Convention Center and Paramount Theater)
  • Westlake (serves Westlake Mall, Macy's, Nordstroms, other retail. Cross connection with the Monorail)
  • University (serves the city's financial core, Benaroya Hall, Seattle Art Museum)
  • Pioneer Square (historical center of Seattle. Many shops, clubs. King County and Seattle City government offices)
  • International District (Safeco and Qwest Fields, cross connections with Sounder)

The tunnel is also an exceptional piece of public art. Every station is themed to the neighborhood it serves. For example, the International District station, which is partially outdoors, is designed like a Japanese garden. Large pieces of Origami, in various stages of being folded, adorn the walls. Another example is the Westlake station, which has a large mezzanine connecting the various retail stores. Seats and walls in the brightly lit station have clothing patterns sandblasted into them.

Portal of one of the bored tunnels

While the tunnel was built primarily to serve dual-mode diesel/electric buses, currently replaced with hybrid diesel buses, as a last-second afterthought tracks were laid in the tunnel for a future light rail system. The future is now with the design and construction of Sound Transit's Link light rail system. However, a couple problems with this existing design were found during the planning stages:

  • The station platforms are too high for new low-floor train cars
  • The rails were not properly insulated, and therefore need to be replaced with insulated rails.

To complete this work, the tunnel was shut down for two years to undergo conversion to handle light rail trains. The Link Light Rail system opened in July, 2009. Buses and trains now share the tunnel, making it the only tunnel in the world with both modes of transport.

I have used the bus tunnel many times while in Seattle, especially since it is part of the Ride Free Zone downtown. This makes it an effective means to access many locations in the city. With one end connecting to Sounder and the other to the Monorail, it serves an important purpose in connecting transit users to downtown effectively. Now with the addition of Central Link the tunnel also serves light rail riders from the South end and soon, the University of Washington.

I started a new job in downtown in 2010. With the employer being just a couple blocks up from the University Street station, I use the tunnel every day. It works great coming in using Link, and also cross-connecting with the Sounder.

Interesting Facts: Back to Top

  • During construction of the Pioneer Square station, a large flywheel from the Madison Street Cable Car Line was found in a vault and now is on display in the station.
  • A large footing for the last pylon of the Seattle Center Monorail can be viewed overhead in the Westlake Station Mezzanine.

Links Back to Top

Map: © King County METRO
Image: © Ben Brooks