Light rail service to Northgate begins in October Light Rail from Northgate to Lynnwood. (KIRO Radio, Chris Sullivan) Sound Transit will start running light rail trains between the University District and Northgate on Oct. 2, 2021. The 4.3-mile extension has been under construction for nine years, with most of the route underground. “Our City is under construction before our eyes, and investments like light rail will be transformational for North Seattle,” Sound Transit Board Member and Seattle Mayor Jenny Durkan said in a news release. “We are building a more connected city that has safe, affordable, and reliable options for people walking, rolling, taking transit, and biking, no matter where you live.”