What’s next for the I-405 master plan?

A new flyover ramp at one of King County’s most congested interchanges is expected to improve traffic flow and reduce collisions — and more work is ahead, including express toll lanes that run from Renton to Bellevue.

The Washington State Department of Transportation recently completed the direct connector project, which connects Interstate 405 express toll lanes to the State Route 167 carpool lanes. The direct connector is part of a larger plan for the area, which includes potential for future modifications to the interchange and traffic impacts on city streets.

According to WSDOT, the strategy for the I-405 corridor has been to first fund projects that directly address the worst congestion choke points. In 2015, WSDOT received $16 billion in funding from the Connecting Washington package.

Other parts of the corridor project that would improve the cloverleaf interchange (which slows down traffic) are not yet funded, but include an additional general purpose lane on either side, interchange adjustments, noise walls and nearby street adjustments.

The next step in the I-405 corridor plan is the addition of new express toll lanes from Renton to Bellevue. Construction is anticipated to begin this year and be completed by 2024. According to WSDOT’s website, the project will result in 40 miles of express toll lanes, via the direct connector.

The project includes an additional express toll lane north and southbound, and improvements at two Renton I-405 locations, including the Northeast 44th street interchange, which is being converted into a roundabout system and has resulted in the closure of a local Denny’s. In the works are also improvements to the Southport Drive North/Northeast Sunset Boulevard interchange.

There are also proposals for the Renton to Bellevue widening project that could affect Renton Hill neighborhood access, specifically lengthening the Cedar and Renton avenue bridges, that could begin in 2020. And now a new alternative is being considered.

Staff from WSDOT told Renton Hills Neighborhood residents April 2 that there is talk of using an older idea from the I-405 Master Plan that removes the Renton Avenue bridge and creates a roadway from Cedar River Trail Drive under I-405 instead. The Cedar bridge would be replaced as planned.

WSDOT is in talks with several design builders over this project, and will have a better idea later in the year what the finalized concept will be, the organization reports. This alternative could also potentially allow for improvements to the Cedar River Trail.

Pending legislation sets the timeline for the rest of the project. According to a presentation to the I-405/SR 167 Executive Advisory Group on April 3, the state still needs to authorize the use of express toll lanes. Lack of support could result in construction delays and budget increases for the Renton to Bellevue widening project.

Renton City Council also adopted a resolution April 1 to show full support for state legislation that would offer $16 billion in new transportation funding for more projects on the I-405 corridor, as well as support for toll authorization in time for a 2024 completion. This includes funding for a direct access ramp at North 8th Street to mediate traffic impacts in Renton while connecting commuters to express toll lanes. In ordinance documents, city officials stated this ramp will help communities of color, as well as Boeing and PACCAR employees, on their work commute.

More information on WSDOT corridor projects and other proposed projects is available here.