The SR 520 Bridge Replacement and HOV Program involves a number of large, individual construction projects for the rebuilding of SR 520. Some of these projects had their own planning, design and environmental process. In addition, the I-5 to Medina: Bridge Replacement and HOV Project was the major planning and environmental process for construction of a new SR 520 floating bridge and all remaining SR 520 infrastructure improvements in Seattle between Lake Washington and I-5 – the "Rest of the West."

I-5 to Medina: Bridge Replacement and HOV Project

• 2006 – Published draft environmental impact statement.
• 2010 - Published supplemental draft environmental impact statement.
• 2011 - Issued final environmental impact statement.

Eastside Transit and HOV Project

• 2008 - Conducted environmental scoping.
• 2009 - Issued environmental assessment.
• 2010 - Completed environmental process.
• 2011 - Began construction.
• 2014 - Completed major corridor improvements. 
• 2015 - Completed all construction.

Pontoon Construction Project

• 2010 - Published draft environmental impact statement.
• 2010 - Issued final environmental impact statement.
• 2011 - Began pontoon construction in Grays Harbor.
• 2015 - Completed pontoon construction.

Floating Bridge and Landings Project

• 2012 - Began construction of pontoons in Tacoma.
• 2012 - Began construction of new floating bridge.
• 2016 - Opened new floating bridge to traffic.

West Connection Bridge Project

• 2013 - Began construction of new bridge.
• 2014 - Completed construction of bridge.

West Approach Bridge North Project

• 2014 - Began construction of new bridge.
• 2017 - Opened new bridge to traffic.

Montlake Project

• 2019: Began construction
• 2023-2024: expected completion of construction

SR 520 / I-5 Express Lanes Connection Project

• Spring/summer 2021: estimated start of construction
• Estimated construction duration: 3 years

Montlake Cut Bascule Bridge Project

• WSDOT will conduct additional coordination with community stakeholders and agency partners regarding the scope of the Montlake Cut Bascule Bridge Project.

Portage Bay Bridge and Roanoke Lid Project

• 2023: planned start of construction
• 2029: expected completion of construction