SR 99 Tolling

SR 99 Tunnel Project

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SR 99 Tunnel - Effect on Seattle Traffic

This page talks about how traffic will change after the SR 99 tunnel opens.

Why will Seattle traffic patterns change?

Replacing the viaduct will change how people get around Seattle for many reasons besides tolls:

  • Unlike the current viaduct, the tunnel will not have entrances or exits downtown or in Belltown. Because of this, many drivers who currenly use the viaduct to get into downtown may switch to other routes when the tunnel opens. 
  • A new Alaskan Way surface street will be built in the footprint of the viaduct, with improved connections to downtown Seattle. This road will not have tolls and will be a more direct way to get to many parts of downtown than the tunnel.
  • Downtown traffic patterns will shift as the result of changing transit routes and other construction projects.

What do we know about how toll rates will affect traffic?

We are currently studying how drivers would react to several sets of hypothetical toll rates so we can estimate how much revenue could be raised and how traffic patterns could change based on various toll rate options. 

Initial results indicate that many drivers will choose to use other routes than the tunnel to get into downtown no matter what toll rates are chosen. Once improvements to Alaskan Way are complete, it will provide an additional option for drivers who currently uses the SR 99 viaduct.

More people are predicted to use the tunnel and Alaskan Way during the evening peak commute than today. More people are predicted to choose other routes during off-peak times like mid-day, evenings, and weekends.