When the SR 99 tunnel is open to traffic, northbound drivers approaching the tunnel will have new options for reaching downtown Seattle or bypassing it entirely. Below is a rendering of how the south tunnel portal’s ramps will appear:
New on and off-ramps will connect SR 99 to the stadiums and to a new Alaskan Way surface street that provides connections into the downtown grid. See the Getting Around page for examples of future routes.
Last updated: 12/29/16
A lot of work has already been completed at the south end of the tunnel. Crews have built hundreds of feet of cut-and-cover tunnel, and the future tunnel entrances and exits are visible at the surface. Drivers on SR 99 can see the south portal operations building's glassy exterior, along with its signature yellow ventilation stacks. This building, along with a similar building at the north portal, will be complete in 2017.
The south portal work zone continues to be the main hub for tunnel construction. It's where materials are stored, including the curved concrete segments that make up the tunnel walls. Nearby on Terminal 46, crews load excavated soil onto a barge that takes the soil to a disposal site in Port Ludlow. The soil makes its way to the barge via a conveyor system that grows as the tunneling machine moves forward. More than one million tons of soil have been removed from the tunnel so far.
As part of a separate contract, crews working for Interwest Construction are building the innovative future northbound off-ramp to South Dearborn Street. By combining memory-retaining metal rods and a bendable concrete composite, the future off-ramp will become the first bridge in the world built to sway with a strong earthquake and return to its original shape.