Stride S1 Line

Adding new bus rapid transit service along I-405 and SR 518 between Bellevue and Burien.
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Project map and summary

Map depicting S1 line stations
Map depicting S1 line stations

Project updates

Like many agencies nationwide that are balancing transit operations and mega-project capital expansions, Sound Transit faces rapidly escalating costs in nearly every area of its work.  

The “Enterprise Initiative” is Sound Transit’s comprehensive effort aimed at delivering the maximum benefits of ST3 within available financial resources. As part of this effort, the Sound Transit Board is evaluating different approaches to updating the ST3 System Plan in summer 2026, which may include new ways to build, phase, or sequence projects.  

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Overview

The Stride S1 Line will connect communities along I-405 and SR 518 from Bellevue to Burien. Like all Stride routes, buses on the S1 Line will run every 10 to 15 minutes, 17+ hours per day, seven days a week. The S1 Line will connect to Link light rail stations at the Bellevue Transit Center, above the Bellevue Downtown Station, and Tukwila International Blvd Station. The S1 Line will provide seamless transfers to transit services provided by Sound Transit, and King County Metro. The Stride S1 and S2 fleets will consist of double-decker battery-electric buses, as shown in the graphic below.

 

Rendering of Stride double-decker bus’s side profile. The bus exterior includes stripes as well as the Sound Transit and Stride logos. The right side of the bus has two doors for access, one at the front and one in the middle of the bus.

The project will build five Stride stations, including a new transit center in Renton. New parking will be available at two of these stations by 2034: Renton/NE 44th Station and Renton Transit Center.

As part of the Washington State Department of Transportation (WSDOT) I-405 Master Plan, the S1 Line will benefit from highway improvements for faster travel. In partnership with WSDOT, we aim to improve community safety, transit access, and the travel experience within the I-405 corridor. WSDOT and partner projects in the region are building portions of the Stride system to invest in transportation and pedestrian improvements ahead of Stride service beginning.