Remembering Bertha’s roots: two years of SR 99 tunnel construction in the books

Time-lapse video highlights the hard work that led up to Bertha’s July 30 launch

A lot can happen in two years. Just ask Bertha, the SR 99 tunneling machine.

Two years ago this week, Bertha existed only on paper and her launch-pit site was little more than a field of dirt where the south end of the viaduct once stood. Our contractor, Seattle Tunnel Partners, had just received the go-ahead to complete final design and begin building the SR 99 tunnel.

Then this happened: view SR 99 tunnel time-lapse video on YouTube.

Seems easy when you watch it all unfold in three minutes, but it was considerably more challenging in real time. Trust us. Here’s how it all played out:

Preparing Bertha’s path
By fall 2011, construction was in full swing. Crews were moving utilities and preparing to reroute six blocks of waterfront traffic to a newly improved road beneath the Alaskan Way Viaduct. The traffic switch took place the following spring, clearing a path for crews to begin strengthening the ground along the initial section of the tunnel route.

The digging before the digging
Summer 2012 saw Bertha’s launch pit beginning to take shape to the west of Seattle’s stadiums. Over the next year, crews would remove 86,000 cubic yards of soil from the ground.

Tunneling machine gets a name and a voice to go with its giant green face
A contest among Washington students in fall 2012 gave the world’s largest tunneling machine a name – Bertha – after Seattle’s first and only female mayor, Bertha Knight Landes. Soon after, @BerthaDigsSR99 took to Twitter to announce her presence. She’s been tweeting updates to her followers ever since.  

Bertha on the move
Bertha saved her biggest moments for 2013 – a two-week journey by ship from Japan in spring, followed by her push through the north wall of the launch pit on July 30.

Looking ahead
Tunneling is about moving forward rather than looking back, particularly with Bertha’s biggest challenges yet to come. Still, as we mark two years of tunnel construction, it’s worth taking a moment to remember all the hard work that set the stage for her historic journey.     

Now, back to the digging.