North End

North End

Last updated Feb. 05, 2015

Lane closures on SR 99/Aurora Avenue North wrapped up early, next phase began Feb. 8 

Contractor crews building the northern approach to the new SR 99 tunnel have been working since Jan. 18 to install foundations for four overhead traffic signs on SR 99/Aurora Avenue North between the Aurora Bridge and just north of Mercer Street. Work progressed ahead of schedule and the first phase of work wrapped up one week early. By Friday afternoon, Feb. 5, the median lanes in both directions reopened and the southbound bus-only lane was restored.

Crews will be working for two to three more weeks near Comstock Street to install the final sign foundation as part of the second phase of work.



Lane closure details: 8 p.m. Monday, Feb. 8 to late February

  • The southbound curb/bus-only lane near Comstock Street is closed for approximately one block.
  • An additional southbound lane may close overnight.
  • Buses traveling in the bus-only lane will merge into the general purpose lane a few blocks north of where the bus-only lane currently ends.


Minor electrical work: week of Feb. 8 through early March

As foundation work near Comstock Street progresses, electrical crews will be installing underground electrical cabinets at the sign foundations, wiring for a new traffic camera and connecting communications lines to the existing overhead system. Electrical work is scheduled to take four to five weeks to complete and will require an intermittent, localized lane closure at specific points along SR 99. These closures will be limited to off-peak hours only (10 a.m. to 2 p.m.) and are not expected to significantly impact traffic. The schedule for electrical work is approximate and may change. We will keep the public informed as work progresses.

What’s been happening?

During the first phase of work, crews cut and removed about 1,600 square feet of pavement, drilled four large underground shafts for the sign foundations, installed rebar and poured concrete into the shafts. They also placed new concrete barrier around each of the new foundations for additional protection and support, and began installing underground power and communications lines to support electronic messaging systems related to the future tunnel.   

Since work began, travel times for cars and buses during peak periods in the morning and afternoon remained fairly steady – not just on SR 99 but on nearby arterials as well. So whether you've been leaving your house or work an hour earlier, riding your bike, or avoiding SR 99 altogether, we appreciate your efforts to help us keep traffic moving.

Night work

In an effort to balance the needs of drivers and residents, some work will occur during nighttime hours. An additional southbound lane may close at night to provide extra work space.


For questions or concerns about SR 99 lane closures, contact us at or 1-888-AWV-LINE (298-5463). 


Originally posted Dec. 7, 2015.

Building the north portal

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, and enlarging the image below will display a rendering of the way the future SR 99 will connect with the surrounding surface streets. 


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:

SR 99 tunnel north portal


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. This post explains the tunnel's two operations buildings in more detail.