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SR 520 - I-5 to Lake Washington planning documents

Library > Environmental documents > I-5 to Lake WA

The designs for SR 520 improvements between I-5 and Lake Washington have undergone many iterations of planning, analysis and stakeholder involvement. The I-5 to Lake Washington project page contains a summary of these past processes .

Below are documents produced by these planning efforts.

2014-2015 West Side Design Refinements

January 2015 | Final draft design report

Full draft report - 11 x 17 size


Full draft report - 8.5 x 11 size

Updated cost estimates: one-page graphic (pdf 1.6 mb) and background information slides (pdf 338 kb).

2011-2012 Seattle Community Design Process

Dec. 20, 2012 | Seattle Community Design Process final report (pdf 24.3mb)

Final report broken down in sections

Report in 8.5 x 11 letter format

Public comment summaries

Sept. 14, 2012 | SCDP draft design report

Dec. 2011 | SCDP progress update

Seattle Community Design Process - 2011 Progress Update (pdf 1.32 mb)

Public comment summaries

For copies of the materials presented at SCDP public sessions from Oct 2011 to July 2012, see the chronological list of meeting materials on the open houses and public meetings page.


2011 Record of Decision

  • In August 2011, the Federal Highway Administration published the Record of Decision, which described the project’s course of action and specific mitigation measures. The 2011 Record of Decision can be viewed on the Environmental Documents page within the Resource Library.

2011 - Final EIS Preferred Alternative


  • In January 2011, we published the final EIS, which evaluated the preferred alternative and included a response to comments received on both the draft and supplemental draft EIS documents. The final EIS Preferred Alternative document can be viewed on the Environmental Documents page within the Resource Library.

2010 ESSB 6392 Workgroup

Dec. 22, 2010 | High Capacity Transit Planning and Financing Findings and Recommendations Report

Dec. 22, 2010 | Washington Park Arboretum Mitiation Plan

Final report (pdf 1.96mb)

  • Appendix A : ABGC Coordination Process Matrix (pdf 120 kb)
  • Appendix B : Meeting Summaries (pdf 584 kb)
  • Appendix C : ABGC Letter of Support (pdf 564 kb)
  • Appendix D : Seattle City Council letters (pdf 3.87 mb)
  • Appendix E : SDOT’s Recommended Pedestrian Improvements and Traffic Calming Plan (pdf 331 kb)
  • Appendix F : SDOT’s Arboretum Traffic Management Matrix (pdf 47 kb)
  • Appendix G : Washington Park Arboretum Master Plan Priorities (pdf 170 kb)
  • Appendix H : Public comment summary (pdf 5.3 mb)

Oct. 1, 2010 | ESSB 6392 Workgroup Design Refinements and Transit Connections

Final report (pdf 4 mb)

ESSB 6392 Workgroup Meeting materials

Dec. 13, 2010 - Seattle City Council presentation materials

Dec. 1, 2010 - ESSB 6392 Workgroup meeting

Sept. 13, 2010 - Seattle City Council presentation materials

Sept. 9, 2010 - ESSB 6392 Workgroup meeting #3 materials

Aug. 19, 2010 - ESSB 6392 Workgroup meeting #2 materials

ESSB 6392 Workgroup meeting #2 materials

Aug. 3, 2010 - Seattle City Council presentation materials

July 22, 2010 - ESSB 6392 Workgroup meeting #1 materials

July 19, 2010

2010 Supplemental Draft EIS

  • In 2010, we published the supplemental draft EIS, which builds on the findings of the draft EIS. This was an interim document between the draft EIS and the final EIS. The supplemental draft EIS evaluated new design options proposed through the west side mediation process and more details about construction effects and mitigation. The 2010 Supplemental Draft EIS can be viewed on the I-5 to Medina page within the Resource Library.

2009 Legislative Workgroup

2007-2008 Mediation and ESSB 6099

December, 2008 | Westside Project Impact Plan

In 2008, WSDOT, King County Metro and Sound Transit released the SR 520 High Capacity Transit Plan which defined bus rapid transit across the corridor

2006 Draft EIS

  • In 2006, WSDOT published a draft environmental impact statement (EIS) describing how the SR 520 Bridge Replacement and HOV Project could affect the environment in the project area and how WSDOT would avoid, minimize and mitigate these effects. The 2006 draft EIS can be viewed on its own page within the Resource Library.
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