Latest Program News

  • Final filling begins for the Battery Street Tunnel

    The final ingredient in the layer cake that is filling up Seattle’s Battery Street Tunnel is being mixed starting this month. Crews have begun pouring a special type of concrete into the tunnel through ventilation grates and holes in the tunnel’s roof. This flowable material will fill in the remaining space within the old SR 99 highway tunnel.
     
    Crews working for the contractor, Kiewit, are starting the pouring at Denny Way, the tunnel’s north end. The low-density cellular concrete (LDCC) is mixed on-site with mobile equipment staged adjacent to Borealis Avenue. The mixing plant will stay there for several weeks, then move to the Battery Street Tunnel’s south portal, which is adjacent to First Avenue. Over the next several months, crews will pump LDCC from the south portal area using a series of  hoses placed along Battery Street.
     
    Trucks and construction equipment positioned on edge of Borealis Avenue
    Above: LDCC mixing equipment staged along Borealis Avenue, just south of Denny Way

     

    What is low-density cellular concrete (LDCC)?

    LDCC is produced by mixing water and slurry (a liquid form of concrete) and then injecting a foaming agent. This process produces a kind of concrete meringue that is lightweight and does not get as hard as typical concrete. The material’s lightweight property helps protect the utilities beneath it from excess weight, while its lower strength will allow future crews to dig through it when required to reach those utilities. A 5-gallon bucket of LDCC weighs about 20 pounds, versus 100 pounds for standard concrete.

    This final stage of filling will use approximately 40,000 cubic yards of LDCC to fill the roughly nine vertical feet left in the tunnel. This is a lot of material – by comparison, CenturyLink field reported using about 10,000 cubic yards of concrete in its construction.

    The LDCC is the third type of fill material crews have used in the Battery Street Tunnel. First, crews poured crushed rubble produced from viaduct rubble into the tunnel with trucks from the surface. This spring and summer, crews have been filling the tunnel with Controlled Density Fill concrete (CDF) around the new utilities to protect them from heat and impact. The LDCC is the final layer in the cake, filling in the headroom between those utilities and the tunnel’s roof.

    What should I expect during construction?

    People traveling in the area should expect single-lane closures on Battery Street and cross streets between First and Sixth avenues, and along Borealis Avenue between Sixth Avenue and Denny Way. The batch machinery and idling trucks will also produce an increase in noise and possible vibration.

    Construction equipment staged adjacent to a gravel patch with Seattle skyline in background

    Above: The mobile LDCC mixing plant staged along Borealis Avenue.

    More work to come

    Fully filling the Battery Street Tunnel is not the end of the job. Once the LDCC is poured, crews will be able to turn to improving the surface of Battery Street. This work has already begun on some blocks, and includes patching over the tunnel’s ventilation grates, building new sidewalk and ADA-compliant ramps, and installing new street lighting. The tunnel’s south portal has been the construction staging yard for the job and will be turned into a slope and then handed over to the City of Seattle. All work on the project is expected to conclude in 2021.

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  • Limited construction resuming on Seventh Avenue North and in Battery Street Tunnel

    Last week crews working for Kiewit Infrastructure West Co. resumed limited work on the North Surface Streets and Battery Street Tunnel projects. Work in these two areas had been suspended since March due to the COVID-19 pandemic. This low-risk work is occurring in accordance with guidance from Governor Inslee and adhering to the state’s required safety plans required of all contractors.


    Work on Seventh Avenue North

    Orange construction barrels run down the middle of Seventh Avenue North

    Above: View looking north along Seventh Avenue North at Thomas Street. The barrels mark where center median construction will resume.

    Before work was suspended, crews had begun building the permanent center medians on Seventh Avenue North. Crews will soon begin breaking out asphalt in the middle of the street where the permanent, planted medians will be built. Forming the concrete curbs and landscaping will come later, when additional types of work are approved. Some turn restrictions remain in place between Denny Way and Harrison Street.


    Work on Battery Street

    Construction equipment sitting on dirt slope with buildings in background

    Above: Construction equipment staged at the south portal of the Battery Street Tunnel, just west of First Avenue. Restoring this area is one of the elements of the project still to be completed.

    There is a substantial amount of work remaining to decommission and fill the Battery Street Tunnel, with construction scheduled to extend into 2021. This includes utility work as well as filling the final (top) seven feet with a low-density concrete. Above ground, on Battery Street, crews still have street restoration activities to complete, such as building ADA-compliant curb ramps and removing and patching over the tunnel’s ventilation grates.

    This month crews are beginning limited work inside the tunnel, preparing for the time when tunnel filling can safely resume. When additional construction activities are cleared to resume, crews will begin pouring and forming ADA-compliant ramps along Battery Street at its intersection with First, Second, and Fourth avenues.

     

    Looking ahead

    “Phase Two” of Governor Inslee’s restart plan will allow a wider range of construction activities. On our project, that will include much of the construction that remains. In addition to the work activities noted above, work will resume at the intersection of Seneca Street and First Avenue. There, crews will rebuild the sidewalk on the west side of First Avenue and do other restoration activities associated with the viaduct off-ramp that used to terminate at the intersection. We encourage our neighbors to subscribe to our construction emails for updates on when that work will resume.

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  • Status of project construction work

    In March, the Washington State Department of Transportation suspended work on nearly all of its construction projects statewide. This included most Alaskan Way Viaduct Replacement Program construction on the Battery Street Tunnel and the North Surface Streets projects.
     
    Last Friday, Governor Inslee issued new guidance on the conditions under which low-risk construction may resume. WSDOT is requiring all contractors to develop plans that adhere to the safety protocols outlined in the Governor’s direction. WSDOT and our contractor Kiewit will work closely to identify which project elements may be resumed, and the safety plans and protocols that must first be in place to protect the safety of crews and the public at large.
     
    Certain types of work deemed critical were exempted from the March work-suspension order. On this project, that work entails:
    • Installing a water line at South King Street. That work began in early April and continues, with crews working daytime hours and completing work in accordance with CDC guidelines to ensure the safety of crews and the public.
    • Upcoming weekend work at First Avenue and Seneca Street. This work, at the abutment of the old viaduct off-ramp, requires deactivating the overhead bus trolley wires. This weather-dependent work is planned for May 9-10. Crews plan to work extended daytime weekend hours (6 a.m. - 8 p.m.), and the work will reduce First Avenue to one lane in each direction from 6 a.m. Saturday, May 9 to 6 a.m. Monday, May 11. 

    Work on the Battery Street Tunnel and Seventh Avenue North remains temporarily suspended. Once plans are in place to address safety protocols, crews will begin working on both projects.

     
     
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  • Battery Street and North Surface Street construction suspended

    In response to Gov. Inslee’s “stay home, stay healthy” order, the Washington State Department of Transportation has suspended work on nearly all of its construction projects statewide. This includes the Alaskan Way Viaduct Replacement Program construction on the Battery Street Tunnel and the North Surface Streets Project. The suspension will last for at least two weeks.

    This temporary halt in construction is needed to help slow the spread of the COVID-19 pandemic and protect the health and safety of our employees, contractor crews and the public at large. We will look to restart our projects when the Governor’s Office and health officials determine it is safe to do so.

    Crews are still planning to complete critical work on a water line at South King Street. This work is exempted from the halt in construction and is scheduled to begin as soon as April 6. That work will be completed in accordance with CDC guidelines to ensure the safety of crews and the public.

    Our contractor Kiewit has closed their jobsite so the site does not pose hazards to the public while construction is halted. We will post updates to our program website and via our construction email list when we have new information to share. If you have any questions about our work, please email us at viaduct@wsdot.wa.gov or reach out via Twitter @BerthaDigsSR99. In the meantime, we wish good health to you, your families and friends. Stay safe!

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