Inside the Massive Tunnel Seattle Built to Replace an Aging Highway
Seattle’s waterfront is getting a makeover. It hasn’t been a particularly rapid affair (certainly nothing for Elon Musk to measure himself against), but the workers building a tunnel to replace a section of elevated roadway, and reopen up the city to the ocean, are nearly ready to introduce the public to their handiwork.
The whole project started after a 2001 earthquake damaged the Alaskan Way Viaduct, which has carried State Route 99 through Seattle since the 1950s, dividing the city’s downtown from the short of the Puget Sound. Fearing the double-decker roadway wouldn’t withstand another shake, city planners decided to replace it with a two-mile tunnel under the city, and at the same time reintroduce Seattleites to the water. So they brought in Bertha.
The world’s largest boring machine by diameter set to work in 2013, but a planned two and a half year dig became a four-year project when Bertha got jammed after advancing just 1000 feet. Engineers had to dig an entirely new pit to reach the front of the machine and fix its damaged blades.
Bertha finally broke through in April of this year, having dug nearly 1.7 miles of tunnel. Now, Seattle’s builders are kitting out the empty concrete tunnel it left behind with stacked roadways, sprinklers, ventilation systems, and all the other bits you need to move people about below the surface.
The drone fly-through video above is the best look you’ll get at the tunnel under construction, but if all goes to plan from now on, you’ll be able to drive through it in early 2019.