It’s official: Sound Transit will move ahead on its $2.1 billion North Link project, building 4.3 miles of light rail track—mostly underground—from the University of Washington to Northgate. And it will all start this summer, with completion scheduled for 2021.

The Sound Transit board confirmed the effort recently and solidified the plans to construct three new transit stops along the route, as the entire King County region expands its light rail options at an ever-increasing rate. Already, tunnels are being bored from downtown Seattle under Capitol Hill to the University of Washington, set to open in 2016.

The new North Link route, which aims to add over 60,000 daily riders and was approved by voters in 2008, starts at the University of Washington Station near Husky Stadium. It will take riders to Northgate from UW in eight minutes and can do the downtown-to-Northgate ride in 13 minutes. The new route features stops at Brooklyn Avenue Northeast in the University District, in the Roosevelt neighborhood and at the popular Northgate shopping area. Trains will run underground in tunnels from Seattle along Interstate 5 until just south of the Northgate Station. At that point, trains will pop out of the tunnels to stop at the new above-grade Northgate station.

At the already popular transit hub and shopping district at Northgate, which also serves as the northernmost endpoint of Interstate 5’s express lanes for drivers, Sound Transit is offering to participate in a multi-agency effort to build a $20 million pedestrian and bicycle bridge across the interstate in an effort to connect North Seattle Community College.

The Brooklyn Station will be the first stop going north for North Link. The 80-foot-deep underground cut-and-cover site stops below a mix of residential and business districts. Nearby is the “Ave” business district, along with the UW Tower and the northern portion of the University of Washington campus. Sound Transit expects 12,300 people each day to board at the Brooklyn station in the next 20 years.

Near Roosevelt High School, the next underground station, this one 90 feet below the surface, will service the surrounding neighborhood and the Roosevelt business district, including Roosevelt Square, at the tune of about 8,500 riders per day.

The above-grade station, about 25 feet in elevation, will sit near the Northgate Transit Center south of the mall, allowing quick transfers to the transit center and on-site park-and-ride facilities. The station should serve 15,200 riders in the next 20 years, Sound Transit says.

The next move north for Sound Transit include plans to extend from Northgate to Lynnwood.