Ridership on Sounder South is booming, and this is expected to continue as the region grows. To help meet growing demand, in 2016 voters approved the Sounder South Capacity Expansion program and an extension to DuPont. The goal of the program is to expand Sounder capacity and improve rider experience.
 
Sound Transit will expand Sounder platforms to support longer trains, increasing rider capacity by up to 40 percent, and will consider station access improvements, additional service to meet growing demand during peak travel times and the potential for expanded schedule options at other times. Any additional service would require negotiation with BNSF, the railroad that owns most of the tracks used by Sounder.

The first step of the capacity expansion program is creation of a strategic plan to identify projects, service and completion dates. Planning for the first round of projects could begin as early as 2020, and all expansion program improvements will be complete by 2036.

Stay tuned for public input opportunities coming in summer of 2019.