SR 520 Bridge Program: I-5 to Medina Project Design

Simulated view of the new Montlake lid looking west.

View an animated video of the project design: - YouTube - Streaming WMV Stay tuned to the ESSB 6392 Workgroup for the latest design refinements to the SR 520, I-5 to Medina preferred alternative.

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What are the key features of the project design?

• A new six-lane corridor from I-5 to Medina that includes two general-purpose and one transit/HOV lane in each direction.
• Reversible transit/HOV ramp to the I-5 express lanes; headed from the Eastside to downtown Seattle in the morning and from downtown Seattle to the Eastside in the evening.
• A six-lane Portage Bay Bridge with a westbound managed shoulder.
• An urban interchange at Montlake Boulevard.
• A second bascule bridge across the Montlake Cut that provides additional capacity for transit/HOV, bicycles and pedestrians.
• A space between the west approach bridge structures that could accommodate potential future light rail and connect to the University Link light rail station.
• A 14-foot-wide bicycle/pedestrian path across Lake Washington.
• Environmental improvements, including noise reduction features, stormwater treatment, removal of unused R.H. Thomson ramps to restore park land and habitats, and improvements for fish and wetlands plants.

 

Note: Click each image to expand as a PDF.

I-5 interchange

Portage Bay Bridge  Note: Final bridge design aesthetics are still to be determined

Montlake interchange

West Approach and Floating Bridge

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How will the project design accommodate high capacity transit?

Bus rapid transit first

• WSDOT, King Country Metro, and Sound Transit identified bus rapid transit as the first priority for the SR 520 corridor in the December 2008  SR 520 High Capacity Transit Plan (pdf 3 mb).
• A network of bus rapid transit lines could be operational when the new SR 520 corridor is open.
• Maintain opportunities for rail-to-bus transfers at the future Montlake Multimodal Center, which will include the Sound Transit University Link line.

Corridor is rail-ready when the time is right

• The Sound Transit 2 plan funds a planning study of light rail in the SR 520 (pdf 685 kb) corridor to evaluate potential alignments, stations, costs and implementation strategies.

Range of potential light rail alignments from SR 520 to the University Link station

Light rail option 1: Convert transit/HOV lanes to light rail Light rail option 2: Add additional light rail-only lanes

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What will the new west side look like?

Note: Click each image to expand as a PDF.

Sketches of the Montlake vicinity
Bus stops on the Montlake lid	24th Avenue/Montlake interchange	Open space on the Montlake lid
Foster Island	Lake Washington Boulevard	Portage Bay Bridge

Sketches of the SR 520 corridor
SR 520 looking northwest	SR 520 looking southwest	SR 520 looking southeast	New floating bridge

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How was the project design developed?

1997-2000	Trans-Lake Washington Study
	Evaulated multiple options to cross Lake Washington: • Four-lane options • Six-lane options • Eight-lane options • Alternative modes
2000-2004	Trans-Lake Washington Project
	Narrowed options to cross Lake Washington: • Six-lane with high capacity transit options including light rail. • Eight-lane with high capacity transit options including light rail. • Established SR 520 as a tolled facility
August 2006	Draft EIS
	Draft EIS published and analyzes three alternatives: • 4-Lane Alternative  • 6-Lane Alternative     - Pacific Street Interchange option     - Second Montlake Bridge option     - No Montlake Freeway Transit Stop option  • 8-Lane Alternative
December 2006	Gov. Gregoire report: A Path Forward to Action
	Identified the 6-Lane Alternative as the state’s preferred alternative
Spring 2007	Legislature passed ESSB 6099
	• Began mediation process • Endorsed 4+2 configuration (four general-purpose lanes and two transit/HOV lanes) • Began developing SR 520 High Capacity Transit Plan
December 2008	Mediation ends SR 520 High Capacity Transit Plan completed
	Mediation group identified three six-lane design options to analyze in Supplemental Draft EIS: •  Option A with suboptions (pdf 8 mb) • Option K with suboptions (pdf 8 mb)  • Option L with suboptions (pdf 8 mb) WSDOT, King County Metro and Sound Transit released SR 520 High Capacity Transit Plan which defined bus rapid transit across the corridor
Spring 2009	Legislature passed ESHB 2211
	Authorized tolling on SR 520 and formed SR 520 Legislative Workgroup
January 2010	SR 520 Legislative Workgroup Supplemental Draft EIS
	SR 520 Legislative Workgroup recommended a six-lane design option with an interchange at Montlake Boulevard (Option A+) Supplemental Draft EIS published and analyzes three 6-Lane Alternative design options: • Option A with suboptions • Option K with suboptions • Option L with suboptions
April 2010	Preferred alternative
	State identifies preferred 6-Lane Alternative • I-5 interchange (pdf 426 kb) • Portage Bay Bridge (pdf 514 kb) • Montlake interchange (pdf 486 kb) • Floating bridge and west approach (pdf 333 kb)   • Montlake multimodal operations (pdf 1.5 mb)