Congratulations to Sound Transit for completing their tunnel, at least the big digging part. The last tunnel segment of the Northgate Link Extension was finished with a lot less fanfare than Bertha’s progress. Boring machine ‘Brenda’ and ‘Pamela’ dug seven miles of tunnels (as compared to Bertha’s eventual 1.76 miles) and installed 7,352 concrete rings (as compared to Bertha’s eventual 1,426). Of course, Bertha is much bigger at 57.5 feet across instead of Brenda’s more delicate 21.5 foot diameter; so, comparisons are a bit tougher to make.
The good news is that with the main tunnels dug, the rest of the tunnel construction gets easier. The two big bores are easy to see, but there are 23 cross tunnels to be dug, safed, and equipped. There’s plenty of work to do; but most of it will be less showy than the video of Brenda breaking through the last bit of dirt (and a bit of sacrificial support wall.)
If all goes well, Sound Transit expects riders to be very happy.
“Riders using Northgate Station will enjoy seven-minute rides to Husky Stadium, 14-minute rides to downtown and 47-minute rides to Sea-Tac Airport.“
Until then, celebrate a bit of boring success, and somehow navigate Seattle’s traffic. Stay tuned for updates on Bertha’s progress.