• Fly the SR 99 tunnel – from the Space Needle to the stadiums

    Today we are excited to share a drone's-eye view of two miles of tunnel in two minutes. This video captures the ongoing construction of the interior roadways, safety systems and other elements that will carry and safeguard drivers passing beneath downtown Seattle in the new SR 99 tunnel.

    The drone enters at the tunnel’s north end, near Seattle Center. Crews are building the tunnel’s interior structures starting from the south, so as the drone advances the tunnel becomes more complete. The drone flies along the tunnel's upper deck, which is 85% built. At the tunnel’s south end, the drone passes from the bored section of the tunnel (9,270 feet long and dug by Bertha, the tunneling machine) and into the cut-and-cover section, built in the launch pit where Bertha began her tunnel drive.

    One big tunnel element not seen in this video is the tunnel’s lower deck. In early November, the tunnel contractor Seattle Tunnel Partners plans to begin delivering large, prefabricated roadway panels to build that deck (the future northbound roadway). You can track progress on that and other tunnel elements on our tunnel progress tracker.

    There’s much work still to come in building the tunnel’s interior roadway and completing systems like ventilation, sprinklers and traffic cameras. We’ll continue to share and document crews’ progress building the tunnel on in our Flickr albums and on Twitter

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  • Progress update: Transforming Bertha's launch pit

    If you’re a fan of our construction cams, this summer has been all about the pits.

    Up at the SR 99 tunnel’s north portal, our disassembly pit camera gave viewers a front-row seat for the SR 99 tunneling machine’s remarkable disappearing act. Down at the south portal, cam fans have seen something equally remarkable – the transformation of Bertha’s launch pit into a section of the SR 99 tunnel.

    The timing of these twin transformations is no coincidence. During tunnel mining, the launch pit served as the access point for delivering tunnel ring segments and supplies to the machine. The pit also housed a major piece of the conveyor belt that delivered muck from the machine to barges docked at Terminal 46 on Seattle’s waterfront.

    After tunnel mining concluded in April 2017, contractor Seattle Tunnel Partners began the transformation of Bertha’s launch pit into a section of the SR 99 tunnel. In June, after removing the conveyor belt, crews started constructing this section of the tunnel. Three months later, the transformation from pit to tunnel is nearly complete. This slideshow shows how they did it.

    Putting a lid on it

    The last phase of the launch pit transformation is underway now. Crews are building the top of the tunnel, a 4 1/2-foot-thick slab of reinforced concrete known as the lid. Building the lid makes it possible to build streets on top of the tunnel. In 2018, crews will rebuild part of Alaskan Way South directly atop what once was Bertha’s launch pit. When the tunnel opens, three levels of roadway will move people north and south across what was once the launch pit.

    This graphic shows a cutaway view of the future tunnel just west of the south portal operations building.

    Diagram showing two decks of traffic in the tunnel, with five lanes of traffic above it on the surface.

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  • Sept. 14 project update: Photos of progress inside the tunnel

    Many different elements of work must be completed before the SR 99 tunnel is ready for traffic. A previous program spotlight went into these areas of activity in detail. The linear distances of completed work are tracked on the progress tracker, which we are updating monthly (look for an update to the numbers soon). 

    But numbers only tell part of the story. This photo slideshow takes you inside the tunnel to see the recent progress being made beneath downtown Seattle.

    Drivers on the viaduct may have caught a glimpse of the recent transformation of the launch pit where Bertha began her journey (see the final photo in the slideshow). This summer, crews working for Seattle Tunnel Partners have been busy transforming the pit into the section of tunnel that will connect the bored tunnel to the SR 99 roadway near the stadiums. We will go more in-depth on this pivotal section of the tunnel in a future program spotlight.

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Program Spotlight

  • Take it down quickly: What we heard about viaduct demolition

    In August, we held an open house and online open house to discuss viaduct demolition. We are planning the work, scheduled to begin in full once the SR 99 tunnel opens in early 2019, and we wanted to tell you what lies ahead and ask for your comments and concerns.

    Thank you to the 12,000 people who visited our online open house and the 150 people who attended the Aug. 10 open house on Seattle’s waterfront. In total, we received 410 responses to our eight-question survey. We will use … more