Program Spotlight 2016

  • A new place to stroll above the SR 99 tunnel

    Frequent observers of the project’s construction cameras may have noticed some white blocks being placed next to the north operations building at the corner of Sixth Avenue North and Harrison Street.

     

     

     

     

     

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    Crews are building a public plaza that will be a centerpiece of the landscaping at the project's future north portal. The … more

  • Coming to the south portal: A “flexible bridge” to stand up to Seattle’s next big earthquake

    When the SR 99 tunnel opens to traffic, drivers on northbound SR 99 will use a new off-ramp near the stadiums to reach downtown Seattle. In addition to linking travelers to their destination, engineers and researchers hope the new ramp will provide a link to something else: earthquake-resistant bridges.

    By combining memory-retaining metal rods and a bendable concrete composite, the future off-ramp will become the first bridge in the world built to sway with a strong earthquake and … more

  • There's more than one way to change a cutterhead tool

    Performing regular maintenance on Bertha, the SR 99 tunneling machine, is critical to the success of the tunnel drive. During each of Seattle Tunnel Partners’ three planned maintenance stops in 2016, crews have spent time checking and maintaining various systems throughout the machine. Specific maintenance needs vary with each stop, but one maintenance item is always on STP’s to-do list: inspection and replacement of cutterhead tools.

    Bertha’s rotating cutterhead has … more

  • Taking stock at the tunnel’s halfway point

    Bertha has reached the halfway point in her journey beneath downtown, but tunneling crews aren't the only ones making progress on the Alaskan Way Viaduct Replacement Program. Here's a round-up of all the work that's happening along the SR 99 corridor. 

    Interior structures

    There's more to building a tunnel than simply digging through the earth. A separate crew is hard at work building the double-deck highway inside the concrete tube built by Bertha.

    The … more

  • New tour lets you "Bike above Bertha"

    The public may not be able join Bertha as she tunnels beneath downtown, but that doesn’t mean you can’t track her journey at street level. We recently launched a bicycle tour that leads attendees along Bertha’s tunnel route.

    The approximately two-hour tours depart from Milepost 31, our information center in Pioneer Square. Attendees pedal with a guide from the south portal to the north portal, learning about the historical, archaeological and engineering aspects of the … more

  • Kids discover engineering at Milepost 31

    What do you get when you combine an engineer, a group of curious young students and a table full of craft supplies? The answer, we hope, is inspiration.

    For the past two years, Milepost 31, the SR 99 Tunnel Project’s information center in Pioneer Square, has hosted engineering activity days for numerous youth groups. These events are designed to teach the kids in attendance about different fields of engineering through a variety of hands-on activities. In addition to having fun, we … more

  • Building the highway inside the tunnel

    Seattle Tunnel Partners is performing routine maintenance on Bertha, but important work is ongoing inside the tunnel. As the video below illustrates, a massive highway-building operation is trailing not far behind the tunneling machine.

    This is no ordinary highway project. It requires a complex choreography to complete this work even as crews mine beneath Seattle. Check out the video to learn how it works.

     

     

     

      … more

  • The story behind the north portal's signature tree

    The signs of summer are everywhere. There’s more sun in the sky and more boats in the water. There’s also more of something that most folks wouldn’t even know to look for: leaves in one of Seattle’s newest trees.

    Allow us to introduce you to the Garry Oak, the area’s only native oak species. Native Garry Oak prairies were once commonly found in Western Washington. This particular Garry Oak was planted this spring a few blocks east of the Space Needle, … more

  • What to expect from Bertha as tunneling continues

    We’ve been hearing a lot of forecasting lately from members of the public tracking Bertha’s progress. We’ve said this before, but now that Seattle Tunnel Partners crews have passed the 25 percent mark of the tunnel drive, it’s worth repeating: Trying to predict future progress is tempting, but there’s no simple equation for doing so.

    Tunneling progress depends on a number of factors, including soil conditions and the need to stop tunneling when Bertha … more

  • Inside tunneling under the viaduct

    After nearly a week of tunneling under the Alaskan Way Viaduct, crews are steadily continuing Bertha’s underground drive towards downtown Seattle. This video gives you a behind-the-scenes glimpse into how the new tunnel is being built, showcasing the complex operations involved in this project. Massive concrete ring segments are transported to Bertha’s segment erector where they are lifted into place, allowing the machine to push forward while the excavated soil is transported … more

  • #99closure feature: Drone footage inside the SR 99 tunnel

    Just a few days before the SR 99 tunneling machine started tunneling under the Alaskan Way Viaduct, the Washington State Department of Transportation flew a video-equipped drone through the SR 99 tunnel to show Seattle Tunnel Partners’ construction progress. There has been continued interest in seeing what has been built below ground and this video gives a glimpse of the tunnel as well as the nooks and crannies of the complex tunneling machine.

    On an average day, the tunnel is … more

  • #99closure feature: Removing soil from the tunnel

    More than 850,000 cubic yards of soil will be removed from the ground during the course of tunneling. To put that in perspective, imagine this: If you piled that soil on the turf at nearby CenturyLink Field, the pile would be about 400 feet tall – more than 100 feet taller than the stadium’s roof.

     

    Excavated soil travels via conveyor belt from the front of the tunneling machine to a barge waiting at the north end of Terminal 46. When the barge is full, it travels … more

  • #99closure prep: Analyzing traffic patterns on the Alaskan Way Viaduct

    Measuring traffic on the SR 99 Alaskan Way Viaduct isn’t as simple as you might think. Traffic volumes vary along the structure. For example, more vehicles drive the section south of downtown than the section near the Battery Street Tunnel.

    But no matter how you add things up, the end result is the same: thousands of vehicles will be forced to find other routes when the viaduct temporarily closes on April 29. And that will equal congestion and frustration, especially for … more

  • Ordinary maintenance, extraordinary conditions

    With Bertha, the SR 99 tunneling machine, having safely reached her planned maintenance stop, Seattle Tunnel Partners is preparing to complete up to one month of planned maintenance. While the maintenance is routine, some of the methods crews will use to complete it are anything but. That’s because they’ll be performing some work in hyperbaric conditions as they get Bertha ready to tunnel beneath the Alaskan Way Viaduct and downtown.

     

    Hyperbaric conditions are those … more

  • Tunnels and earthquakes

    Seattle is prone to earthquakes, so it’s not surprising that one of the most common questions we receive is this: Will the tunnel be safe in an earthquake? 

    All modern structures in the area – including bridges and highways – must be designed with earthquake safety in mind. But geotechnical and structural engineers agree that tunnels are among the safest places to be during an earthquake. 

    Some folks find this counterintuitive. How is it safe to be … more

  • Good news for SR 99 commuters: first phase of lane closures wrapping up early

    Last week we reported that crews were making good progress as they worked to install sign foundations on SR 99/Aurora Avenue North in Seattle. Turns out good progress leads to good news: the first phase of sign foundation work is finishing ahead of schedule. By Friday afternoon, median lane closures should be removed and the southbound bus-only lane will be restored to normal operations.

    It may be tough to tell, but the new foundations for each sign on SR 99 extend 14 to 18 feet … more

  • Sign foundation work progressing well on SR 99 in Seattle

    If you’re a regular user of SR 99/Aurora Avenue North between the Aurora Bridge and just north of Mercer Street, we’d like to thank you for doing your part to help keep traffic delays to a minimum during the past two weeks.

     

    Crews are around the halfway mark for the first phase of sign foundation installation work happening on this stretch of SR 99 and are pleased with the progress they’ve made. Work is continuing on schedule and crews expect to move into the … more

  • The story behind the Aurora Avenue lane closures

    We’re quickly nearing some major lane closures in both directions of SR 99/Aurora Avenue heading into and out of downtown Seattle. Starting Jan. 18 and continuing for several weeks, drivers and bus riders should expect slower commutes and some challenging traffic, which is never welcome news. Why these particular closures now? Please read on.

    What is closing?

     

    The inside lane in each direction  of Aurora Avenue North between the Aurora Bridge and just north of … more