information from Washington State Dept. of Transportation

Less than 12 months ago, the tunneling machine Bertha was assembling tunnel rings beneath the Belltown neighborhood in Seattle. The machine was 2,500 feet away from the finish line near Seattle Center, with an estimated arrival of June 2017.

So much has been accomplished in the past year, highlighted by Bertha’s arrival in April. Today all the rings are built and the tunneling machine is entirely disassembled. Inside the tunnel, the southbound deck is 99 percent complete and the northbound deck stretches over 2,400 feet.

The contractor crews from Seattle Tunnel Partners completed far too much work this year to capture in one video, but here is a year-end review:

Other highlights from a successful 2017:

• Jan. 16: After a maintenance break, tunnel mining resumes with less than 2,500 feet to go (of 9,270 feet)
• February: Bertha passes beneath the Battery Street Tunnel; crews begin installing the tunnel’s mechanical, electrical and plumbing systems
• March: A 360-degree video takes you inside the tunneling machine and the SR 99 tunnel
• April 4: Tunneling breakthrough, viewed online by more than one million people
• May 3: First piece of Bertha is lifted from the disassembly pit
• May 31: Innovative earthquake-resistant bridge is completed on time and on budget
• June: Bertha’s disassembly continues as the 2-mile-long conveyor belt is removed
• Aug. 3 – 14: We hold our first open house to discuss viaduct demolition
• Aug. 23: The final piece of Bertha is lifted from the disassembly pit
• Oct. 20: We fly a drone in the north portal and out the south portal
• Nov. 2: The first panels for the tunnel’s northbound (lower) deck arrive in Seattle
• Nov. 25: Milepost 31 closes after six successful years and a virtual library opens
• December: Crews prepare for the final of 172 concrete pours to create the tunnel’s southbound (upper) deck

A big thank you to everyone who tuned in this year as we reported on the progress being made to replace the Alaskan Way Viaduct. Stay with us for 2018 as we near completion of the tunnel!