Tag Archives: Bertha

Big, New Seattle Tunnel Will Need Tiny Trucks to Maintain It

When a really big tunnel needs really small trucks…


When the SR 99 tunnel opens, a fleet of tiny trucks will help WSDOT crews maintain the tunnel – traveling in places most of us will never see. While you drive underneath Seattle, your car might be just a few feet above maintenance workers doing their jobs in these bright, yellow trucks.

All nine trucks are electric and will be housed in the tunnel’s north operations building where they can be recharged by simply plugging them into a standard outlet.

Bigger maintenance jobs will require bigger equipment, like bucket trucks and flatbed lift trucks. All total, more than 30 pieces of equipment will make up the tunnel maintenance fleet dedicated to traffic and maintenance inside Seattle’s newest tunnel.

The tunnel could open as soon as this fall, after an approximately three-week viaduct closure to realign SR 99 into the new tunnel.

WA Dept. of Transportation Update on Seattle’s Alaskan Way Viaduct Replacement Program

Alaskan Way Viaduct Replacement Program News

March 29, 2018

Crews install the tunnel’s last northbound roadway panel

Earlier this month, Seattle Tunnel Partners installed the last of the 1,152 road panels that together form the tunnel’s lower (northbound) roadway. A double-deck highway now runs nearly two miles end to end inside the tunnel. Our new video shows a special crane lifting the final panel into place.

New video shows “smart” systems in SR 99 tunnel

Seattle Tunnel Partners is now installing and testing the tunnel’s operational and safety systems. Inside the tunnel there will be more than 300 cameras to monitor traffic and security at all times, automatic ventilation systems designed to keep air quality and visibility high, and automated sprinkler systems designed to put out a fire quickly. Together, these new systems will make the SR 99 tunnel one of the “smartest” tunnels ever built. This new video explains how the critical air quality and fire safety systems work together.

Thousands of components that make up the tunnel’s safety and operational systems will be tested at least three times. After the systems are verified, STP will hand the tunnel over to the Washington State Department of Transportation so a different contractor can realign SR 99 and build the final ramp connections to and from the tunnel. Stay tuned to our website for more updates as work progresses.

Sign up for our viaduct demolition email list

If you would like to receive updates on viaduct demolition, please send an email to viaduct@wsdot.wa.gov and ask to receive updates on demolition work. We will use this email list in the months ahead to share information about the work.

Regular updates about the program are available on our website and on Twitter by following @BerthaDigsSR99.