The work at State Route 520 has never really gone away. Ever since the world’s largest floating bridge opened—a completely new bridge to replace what was the world’s longest floating bridge—across Lake Washington in April 2016, all eyes shifted from State Route 520 and work east of the bridge to the State Route 99 project, which included the bored tunnel under downtown Seattle in an effort to replace the Alaskan Way Viaduct.

Washington State Dept. of Transportation has put the 520 route back at the top of the major project to-do list with the “Rest of the West” project list.

Spring 2019 offers the first phase of the next series of 520 projects in the Rest of the West package, covering the area west of Lake Washington and the floating bridge to the highway’s connection to Interstate 5 in Seattle. 

Starting in spring, construction launches on the Montlake portion, led by Graham Contracting. Then, in subsequent years, expect construction on a SR 520/I5 Express Lanes Connection Project, a new Portage Bay Bridge, the second of two parallel west approach bridges across Union Bay, a new bicycle and pedestrian land bridge over SR 520, new bus and carpool connections, two landscaped highway lids and a second bascule bridge over the Montlake Cut.

The project aims to replace 1960s-era bridges deemed structurally vulnerable to severe storms or earthquakes and provides an opportunity to ease congestion on the four-lane highway, according to WSDOT material. 

The Montlake Project, which starts first and should last four to five years, includes work to create the West Approach Bridge South for three lanes of traffic approaching the floating bridge eastbound, a new Montlake lid and interchange and the land bridge over the highway. Graham Contracting was awarded the design-build project in late 2018 at approximately $400 million. 

With construction starting in 2020 and expected to last three years, the planned new connection between SR 520 and I-5’s express lanes include reversible transit/HOV connection between the two transportation systems. 

The Portage Bay Bridge and Roanoke Lid Project are both scheduled to begin in 2023 and last about six years while a timeline has still not been set for the second bascule bridge over the Montlake Cut. 

In all, these projects are authorized by the state legislature at $1.64 billion. 

“We know tens of thousands of people use the SR 520 corridor every day, including many bus riders, drivers, walkers and bikers and we’re committed to keeping you moving during construction,” Denise Cieri, WSDOT SR 520 program administrator, wrote in a newsletter to the public. 

The 1964-designated highway—the original bridge opened in 1963—connects Seattle to Redmond and other points east of Seattle.

Follow Tim Newcomb on Twitter at @tdnewcomb