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I-405 Master Plan

What is the I-405 Master Plan?
Interstate 405 has long been one of the state’s most congested corridors. In 2002, after a three-year study of the area and extensive work with stakeholders up and down the corridor, WSDOT adopted an environmental impact statement for the corridor, which became the basis of the I-405 Master Plan.

The Master Plan is a set of long-term improvements we are working to achieve within the I-405 Corridor Program. The improvements are designed to get more people moving through the corridor with the completion of more than 150 individual but coordinated projects.

Is the Master Plan just highway improvements?
The plan includes all transportation modes, including new lanes in each direction, a corridor-wide bus rapid transit (BRT) line and bicycle and pedestrian paths. The plan aims to address bottlenecks such as the SR 167, SR 520, SR 522 and I-90 interchanges, improve key arterials, build new transit centers, and add about 1,700 new vanpools and over 5,000 park and ride spaces.

The I-405 Master Plan includes:

  • Up to two lanes to on I-405 in each direction
  • A Bus Rapid Transit (BRT) line with stations along I-405 and expanded transit centers
  • Improvements to key arterials
  • 1700 new vanpools – a 100% increase
  • Increasing local transit service by 50% within the corridor
  • 5,000 new park-and-ride spaces
  • Eight new pedestrian/bicycle crossings over I-405
  • Potential managed lanes system

How are we doing so far?
For the last 15 years, we’ve focused on addressing the worst chokepoints first in Bellevue, Bothell, Kirkland and Renton. After several years of study, we also received Legislative direction to build express toll lanes between Bellevue and Lynnwood on I-405.

Here is an overview of our progress toward building Master Plan elements as of 2017:

Project Progress
 Park and Ride expansions  13% complete or funded
 Transit center expansions  70% complete
 Bus Rapid Transit stations  91% complete or funded
 Local arterial improvements  50% complete
 Add 2 lanes in each direction  45% complete or funded
 Transit service increase  62% complete or anticipated
 Direct Access and Direct Connectors  19% complete or funded
 Vanpool service increase  40% complete
 Pedestrian/bicycle improvements  65% complete or funded














Some of our active projects within the I-405 Master Plan include: