Bertha faces the finish line in final stretch under Seattle

Tunnel crews have stopped Bertha — with the finish line in sight — under Denny Way and Sixth Avenue. But tunnel officials need to check their trajectory — the machine is a few inches off its path.

Related: Boring machine delays are nothing compared to early Seattle construction

Crews will perform maintenance during the stop. Mining is expected to restart next week. The corrections don’t seem to be delaying the machine from hitting the surface earlier than previously thought. Bertha was expected to reach its goal in June. Now, WSDOT reports, it is slated to break through the surface in May.

Seattle Tunnel Partners is conducting more surveys to determine how it will make adjustments to Bertha’s path. It’s not the first time crews have had to stop to take a second look. Adjustments were made to the machine’s trajectory after it left the repair pit in 2016, according to WSDOT.

Between Bertha and the finish line

Two blocks, between Denny Way and Thomas Street, now stand between the machine and the disassembly pit.

The numbers:
• 960 feet remain between Bertha and the disassembly pit
• The conveyor belt removing soil from the tunnel stretches for more than a mile and a half through the tunnel
• 1,270 of 1,426 rings have been constructed to form the walls of the tunnel
• Bertha is less than 100 feet below ground

While there are only two blocks to go, Bertha will primarily be mining underneath Sixth Avenue, parallel to the road.

Buildings on Sixth Avenue include:

West side
• A building constructed in 1950 — currently a Walgreens
• A condo building, constructed in 2010
• Office buildings constructed in 1959, 1961, and 1962
• A parking lot

East side
• A condominium built in 2008
• An office building, constructed in 2013
• A hotel built in 1959
• A parking lot
• An office building, constructed in 1951

The machine started boring on July 30, 2013. Nearly four months later, the project started running into problems and movement halted. Crews dug an access pit and Bertha moved into it for repairs in February 2015. After months of work, and years of delay, the machine continued along its path in late 2015.

Things have run smoothly since then — despite one sinkhole left in the boring machine’s wake. It took around eight months for Bertha to move 4,000 feet, and has taken 13 months to get to its current point, with crews constructing the new SR 99 tunnel the entire way.

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