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.
WSDOT received nine new maintenance vehicles over the summer. The vehicles will move into the new SR 99 tunnel after tunnel contractor Seattle Tunnel Partners completes all tunnel systems testing and turns the tunnel over to WSDOT. The four-wheelers will travel the two-mile road beneath the tunnel’s lower roadway; the smaller, three-wheel versions can drive in the narrow corridors on the tunnel’s west side (see graphic below).
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.
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.
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