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.
Last updated Sept. 9, 2015
Future Aurora Avenue North connection
Crews are building the future connection between the tunnel and Aurora Avenue North, and new on- and off-ramps at Republican Street. In late August, traffic was shifted to new lanes so that work can continue.
North portal progress
Seattle Tunnel Partners continues to build the tunnel's future north portal. Here's a shot looking south at the portal in June 2015:
North operations building construction
STP crews near the receiving pit are hard at work on the north operations building. Crews installed the building's yellow ventilation stacks in July. explains the tunnel's two operations buildings in more detail.