Work is progressing on the three blocks of Seventh Avenue North in the South Lake Union neighborhood between Denny Way and Harrison Street. (This stretch of road used to be called Aurora Avenue North.) The North Surface Streets Project will turn what had been highway ramps and the sunken approach to the Battery Street Tunnel into a surface street with north/south bus lanes and signalized intersections at John and Thomas streets.

The project is phased to keep vehicles moving on Seventh Avenue North during construction. Next week the work zones will shift to accommodate new areas of construction. These lane configurations will be in place 24/7 for about four weeks. Here are the changes coming May 13 – 14:

• Overnight closure: Northbound Seventh Avenue North fully closed, 9 p.m. Monday – 5 a.m. Tuesday, so crews can establish new work areas.
• Lane Shift: Beginning Tuesday, the northbound lane of Seventh Avenue North between John and Harrison streets will be shifted onto new concrete. No turn movements will be affected.
• Lane reduction: Beginning Tuesday, Seventh Avenue North will be reduced to one northbound lane north of Denny Way.
• Borealis Avenue narrowed: Borealis Avenue will be tapered down to one lane to accommodate Battery Street Tunnel filling operations and to align traffic with the single lane of Seventh Avenue North that begins north of Denny. The taper will change sides of the street depending on what work activity is being performed. The bus stop will remain open.

Removing the left lane north of Denny Way will give crews space to dismantle and fill the Battery Street Tunnel’s portal and raise the trench to ground level. Shifting the travel lane at John Street will provide space to work on Seventh Avenue North’s future outside lane between John and Harrison streets. See the map at right (click for larger version).

Future work

Later this month, Denny Way will be reduced to one lane in each direction for overnight utility work beneath the street. Later this summer, the contractor will move into the next major phase of the North Surface Streets Project, when Seventh Avenue North's travel lanes in both directions will be shifted into the center of the road so crews can work on the outside lanes.

The decommissioning of the Battery Street Tunnel enters a new phase next week, when the contractor, Kiewit, begins to fill the tunnel from the surface of Battery Street.

Crews have already cleaned the tunnel of decades’ worth of automobile exhaust and removed the tunnel’s mechanical and electrical systems. They will continue to install sewer lines and conduct other utility work. But starting as soon as next week, the contractor will begin trucking in concrete rubble from the viaduct demolition and sending it into the tunnel using funnels on Battery Street. Crews removed steel rebar from the rubble and crushed the concrete into baseball-sized pieces. 

Caption: The ledge at left is fill material already brought in by truck and compacted to support a new sewer line that will be placed on top. The yellow chute at right is part of the tunnel ventilation system to keep fresh air circulating for workers.

Inside the tunnel, crews will compact the fill using a vibratory roller. The work will last at least three months as crews fill up to about seven feet from the top of the tunnel.

Effects of construction

One lane or sidewalk at a time will be closed on Battery Street between First Avenue and Sixth Avenue, depending on where crews are filling on a given day. The compaction happening inside the tunnel causes vibrations that may be felt on the surface and in adjacent buildings.

Details of the work and what to expect in May and June:

• Battery Street reduced to one lane at various locations, 6:30 a.m. – 3 p.m. Monday – Friday.
• Trucks dumping fill material through a specialized funnel on Battery Street, 6:30 a.m. – 3 p.m. Monday – Friday.
• Vibration from compaction work inside the tunnel 6:30 a.m. – 5:30 p.m. Monday – Friday.
• Funnels and other construction equipment stored on Battery Street when not in use.

People living, working or traveling near the work may see and feel increased noise, dust and vibration during the work hours (weekdays 6:30 a.m. – 5:30 p.m.). The filling operation ends at 3 p.m. to keep Battery Street fully open during the evening commute.

Caption: Side-dumping trucks like the one above will deposit fill into funnels on Battery Street.

The Battery Street Tunnel, like the Alaskan Way Viaduct, is seismically vulnerable. Decommissioning it improves surface mobility by allowing three blocks of Seventh Avenue North (formerly Aurora Avenue North) to be rebuilt into a two-way surface street with four-way intersections and bus lanes. For a weekly email update on Battery Street Tunnel construction progress, join our email list.

If you live, work, shop or travel along Seattle's waterfront, chances are you've stopped to watch large machinery doing downright rude things to the Alaskan Way Viaduct. Contractor Kiewit began removing the viaduct in February, producing dramatic changes along the waterfront: 

Above: Central waterfront demolition as of April 6, 2019

Demolition happens in a specific sequence, with the roadway deck being punched out first, then the structure's girders and columns being munched into rubble. The rubble on the ground is crunched and sorted, and then hauled away by truck. We captured a timelapse of this process from start to finish: one span being demolished over the course of about a week. 

Want to watch the process in person? Demolition will continue along Alaskan Way all spring, with active demolition typically occuring 7 a.m. - 5  p.m. on weekdays, with occasional weekend work. You can also follow the progress online via our Twitter feed, SDOT's construction cameras along Alaskan Way, our Flickr photo set, and our own construction cameras which will soon capture the work as it moves north.