Latest Program News

  • Kiewit wins contract to demolish the viaduct

    Today, Kiewit Infrastructure West Co. was named the apparent-best-value contractor for the project that will demolish the viaduct, decommission the Battery Street Tunnel and reconnect city surface streets just north of the new SR 99 tunnel.

    The project’s design-build contract, which includes both design and construction services, is valued at $93.7 million. Kiewit submitted the apparent-best-value bid – a combination of points received for their technical proposal and their price.

    Timelines for the work will emerge after the contract is finalized and the contractor receives approval to begin design work. After that point, WSDOT will be able to share more specifics about how demolition and decommissioning will proceed.

    Last year we combined three projects into one in order to save construction time and reduce risk, so this project entails more than just demolishing the Alaskan Way Viaduct. Kiewit will be responsible for:

    • Removing the Alaskan Way Viaduct.
    • Removing the Columbia Street and Seneca Street ramp structures.
    • Decommissioning the Battery Street Tunnel, removing utility and mechanical systems, sealing the entrances and filling the tunnel.
    • Raising Aurora Avenue North to grade between Harrison Street and Denny Way, rebuilding the street, and reconnecting Thomas and John streets across Aurora Avenue North.
    • After viaduct demolition is complete, restoring waterfront roadways, sidewalks, street lighting and other elements to a temporary condition until the City of Seattle builds the new waterfront.

    Demolition cannot start until the tunnel opens to drivers, which could be as soon as this fall.

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    Order: 9.1

  • Sprucing up the north portal

    As we’ve mentioned before, the area surrounding the SR 99 tunnel’s north portal has changed a lot over the course of the project. Nearby cranes indicate that there’s still lots of construction in the area, but Seattle Tunnel Partners’ work is beginning to wind down.

    Last month, following years of utility and other construction, STP began restoring surface streets near the north portal. This work is occurring south and west of STP’s work zone, and includes sidewalk and street restoration.

    Closeup view of two crew members installing form work on Thomas Street
    Crews set up forms in preparation for paving Thomas Street near the tunnel's north portal.

    As roadway restoration continues, crews are building the remaining section of the tunnel’s north operations building. After building out the space that previously housed the tunneling machine’s disassembly pit, crews built the framework for the tunnel’s north operations building. They’re now working on the interior of the building.

    View of the tunnel's north operations building with street restoration in front
    Crews rebuild the tunnel's north operations building behind Thomas Street restoration.

    The latest notification for street restoration is available on our construction notifications page. You can also follow progress at the north portal on our construction cameras page.

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    Order: 9.2

  • One year since Bertha’s final breakthrough

    One year ago, with a roar of water and concrete tumbling, the tunneling machine Bertha broke through into the disassembly pit, completing her 1.7-mile journey under downtown Seattle. It was and remains a remarkable engineering achievement.

    At the time, Seattle Tunnel Partners was working on the double-deck highway inside the tunnel and had completed about half of the upper roadway deck. Since Bertha’s dramatic breakthrough, the machine has been fully disassembled and crews have finished building the roadways and walls inside the tunnel.

    What happened to Bertha?

    The machine needed to be removed from the tunnel so crews could finish the tunnel’s roadways. STP spent four months disassembling the machine, cutting it up into pieces small enough to be lifted out by crane. Roughly 8,300 tons of machinery were hauled out of the disassembly pit, to be repurposed or recycled. Approximately 6,850 tons of metal were sent to be recycled, but pieces of Bertha’s signature cutterhead were donated to the Port of Seattle and cutting tools and the machine’s control panel were given to Seattle’s Museum of History and Industry.

    Bertha is no longer around but you can relive her breakthrough moment with our drone video:

    A year in tunnel progress

    Since Bertha placed the last tunnel ring, crews have made great progress on the structures and systems inside. The roadways and walls inside the tunnel are done, with the last of the roadway panels that make up the tunnel’s northbound (lower) deck placed last month. Crews are hard at work installing the electrical, ventilation and other systems that will make the tunnel functional and safe.

    At the north and south portals, all signs of Bertha’s support equipment and the large pits that bookended the machine’s journey have disappeared. Crews have covered the launch pit and are preparing to build new city streets and intersections. The disassembly pit at the north end has been covered and the final section of the north operations building is taking shape on the surface.

    Other highlights of construction progress since Bertha’s breakthrough:

     

    While the past year has seen impressive progress, there’s still plenty of work left to do. Before the tunnel opens, crews must finish installing the tunnel’s mechanical, electrical and plumbing systems, then test them to ensure they function properly. Stay tuned as we continue to report contractors’ progress building toward the tunnel’s opening, which could happen as early as this fall.

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    Order: 9.3

  • The roads are installed – now it’s time to finish the tunnel’s smart systems

    A double-deck highway now runs end to end inside the new SR 99 tunnel. Earlier this month, contractor Seattle Tunnel Partners (STP) installed the last of the 1,152 road panels that together form the lower (northbound) roadway.

    Now crews are installing and testing the tunnel’s operational and safety systems. It’s a big job. Inside the tunnel there are:

    • More than 300 cameras to monitor traffic and security at all times as part of an incident-detection system.
    • Automatic ventilation systems designed to keep air quality and visibility high.
    • Automated sprinkler systems designed to put out a fire quickly at its source.

    Together, these systems will make the SR 99 tunnel one of the "smartest" tunnels ever built. This video explains how the critical air quality and fire safety systems work together:

    Thousands of components that make up the safety and operational systems will be tested at least three times – once to make sure they work, then to make sure they work as a system, then together with other systems to make sure all systems are integrated and functional. After the systems are all certified, 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.

    WSDOT estimates the tunnel may open to traffic as early as this fall. Stay tuned to our website and our program Twitter account for more updates as work progresses.

    By the miles:

    The SR 99 tunnel has approximately:

    • 95 miles of electrical wiring
    • 21 miles of sprinkler pipes
    • 15 miles of lights
    • 13 miles of fiber optic cables
    • 8 miles of linear heat detectors
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    Order: 9.4