A significant amount of construction continues at the SR 99 tunnel’s future north portal. This is the spot where Bertha, the SR 99 tunneling machine, will emerge at the end of her two-mile journey beneath downtown Seattle.
Our interactive simulation shows you how this area will change during construction.
A look at Bertha's destination
Seattle Tunnel Partners continues to build the pit where Bertha will complete her tunneling journey. Not too long ago, the pit extended another 350 feet north, but that space is now occupied by the cut-and-cover tunnel that will connect the bored tunnel to the surface. Here's a shot of the pit from April 2015:
North operations building construction
Crews near the receiving pit are hard at work on the north operations building, a rendering of which is shown below. This post explains the tunnel's two operations buildings in more detail.
Future Aurora Avenue North connection
Crews are also building the connection between the tunnel and Aurora Avenue North, and new on- and off-ramps at Republican Street. When construction is complete, drivers, pedestrians and bicyclists will be able to travel between South Lake Union and Seattle Center via three improved east-west streets across the new Aurora Avenue North.
Other construction in the area
As you've likely noticed, the north end is bustling with construction activity. In addition to tunnel construction, our partners at the City of Seattle are making great progress on the Mercer Corridor Project. We’re coordinating closely with their construction, and will continue to do so as we move forward.