Video: Sound Transit completes tunneling for Northgate light rail extension More work to go, service not set to begin until 2021

Contractors for Sound Transit on Thursday completed the last tunnel segment for the Northgate light rail extension, set to open in 2021.

Work began on the 4.3-mile extension in 2014, with two tunnel-boring machines removing more than 500,000 cubic yards of material in the process, according to a news release from Sound Transit.

At a cost of $1.9 billion, the Northgate Link will extend light rail service to a station next to the Northgate Mall, with seven-minute rides to Husky Stadium, 14-minute rides to downtown and 47-minute rides to Sea-Tac Airport.

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Thursday's milestone completes the last of six segments that were bored by JCM Northlink LLC, a joint venture of Jay Dee Contractors, Frank Coluccio Construction Company and Michels Corporation.

The contractor will continue working on cross-through segments for emergency evacuation and other purposes, while construction of the Northgate station is set to begin this fall.

Sound Transit announced earlier this month that its new Angle Lake station, one stop south of SeaTac, will open Sept. 24.

Also this fall, voters will have their chance to decide whether to approve or reject the $54 billion Sound Transit 3 proposal that would add 62 additional miles of light rail, as well as more rapid transit buses, heavy rail and more.

Sound Transit has said the ST3 package will cost the average resident about $169 more in annual taxes -- about double what residents are already paying for the Sound Transit 2 package.

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If approved, the ST3 package would add a property tax of $25 per $100,000 of assessed value, as well as a half-percent increase in sales tax and a hike to the car-cab tax. Despite the transit organization’s average estimate, the actual percentage residents would pay will vary widely based on home values, shopping habits, etc.

Daniel DeMay covers Seattle culture, business and transportation for seattlepi.com. He can be reached at 206-448-8362 or danieldemay@seattlepi.com. Follow him on Twitter: @Daniel_DeMay.