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November 20, 2014

Some of the biggest changes — that you won't see

  • Engineers must decide how to bury utilities and meet traffic needs without disrupting urban design plans.
    CH2M Hill



    Probably almost everyone who is familiar with the design for Seattle’s new waterfront has heard one of the core principles of the work: to create a waterfront for all.

    What most people don’t think about, though, is that “all” includes a full plate of (utility-related) spaghetti under the pavement, comprising all of the utilities that need space. These are the same utilities that bring power or communications to every person who lives and works in Seattle, along with heat, water, sewer, gas and even stormwater conveyance.

    Sounds like an engineer’s dream?

    There are also many diverse needs for transportation — the waterfront is a place where pedestrians, bikes, cars, buses and freight all want to be. The key challenges for the waterfront engineers revolve around supporting utility needs and transportation needs — now, and into the foreseeable future — without impacting the urban design vision for an amazing waterfront.

    So what will be on the waterfront that you will never see?

    • Four 115-kilovolt electrical transmission lines: these provide power for most of Seattle

    • Two 13.8-kilovolt electrical distribution networks: these provide power to all the businesses along Alaskan Way

    • Combined sewer overflow pipes: environmental regulations require reducing sewer overflows throughout the city, and two of outfalls are on the waterfront

    • Water and sewer lines

    • Gas lines (high and intermediate pressure)

    • Steam pipes

    • Communications lines for a multitude of telecom companies

    Photo courtesy of CH2M Hill [enlarge]
    Crews moved big transmission lines off the Alaskan Way Viaduct to a permanent location underground.

    Engineers are focused on making all of this invisible; these pipes and duct banks need to be installed in the right place the first time, out of the way of urban design elements. The engineers also need to make sure that the utilities can be built or relocated without cutting off service to the city or neighboring businesses.

    If, when you visit Seattle’s future waterfront, you are aware of the utilities buried beneath the pavement — to the detriment of the amazing urban design and stunning natural setting — the engineers will have fallen short of their goals.

    Places for people

    You will, of course, see the response to transportation needs. There must be a road along the waterfront.

    It will provide access for the businesses along the waterfront and downtown core, and will support transit service and ferry traffic. It will create a new connection between state Route 99 down by the stadiums, through downtown, and up into Belltown.

    The transportation project is not just about the road, though. There is an equal need for places for people — pedestrians and bikes, walking paths and park areas.

    Pedestrians will have a beautiful, wide promenade along the water, along with more traditional sidewalks on either side of the street. High numbers of pedestrians are anticipated on the rebuilt waterfront.

    Back in the summer of 2012, pedestrian volumes of more than 30,000 people were counted in a single day. While there is not a good crystal ball that can project the change the removal of the Alaskan Way Viaduct will bring, the engineers are planning for summer days with double that count of people.

    Bicycles will be accommodated with a dedicated two-way protected bike path. Bikes will be separated from adjacent vehicle traffic, and pedestrians will be separated from bikes, enhancing safety and enjoyment for everyone. To serve commuting cyclists, the bike path (called a cycle track) will connect into the existing regional bike trails north and south of downtown.

    New route to downtown

    One big challenge in building this space is that this promenade area (picture a long park running the length of the water) is where Alaskan Way was before the seawall construction began. Streets are a natural place to put things underground (things like utilities) but utilities don’t make good companions in parks.

    Tree roots and pipes can create maintenance issues in the future, and no one wants to build a park that needs to be ripped up again later. So — back to the invisible utilities — the coordination for this work is challenging and critical.

    With the removal of the viaduct, cars and buses coming from West Seattle will need a new route to get into downtown. They will bypass the tunnel portal and come in along the new Alaskan Way.

    The new street, along with improvements to streets heading east into the business core, will take the place of the viaduct ramps we have today on Columbia and Seneca streets. New lanes for transit are included to replace and improve upon the bus service that now uses the Seneca and Columbia ramps to access downtown. Ferry-queuing traffic also needs a place — Colman Dock will still be a critical route to popular places across the water.

    Further, there is a major Port of Seattle container facility just south of downtown, driving freight demand and need for access to Ballard, which will be added into the general demand by people who are trying to get around.

    The design strategy here — especially at the south end of the project, where the street will be at its greatest width — has been to provide generous sidewalks and wide, landscaped medians to provide areas for people, with some distance to the traffic that has to be supported to keep our city moving.

    The next major challenge is another one you will not see.

    There are a lot of moving parts along the waterfront today. The new tunnel and the seawall project are two enablers — without these, there would be no new waterfront for all.

    Both of these projects are underway. For both, every day brings new challenges and the potential for change, and the waterfront team is working to respond to these changes, looking for ways to make sure that what gets built only gets built once.

    These are just a sampling of the engineering challenges the waterfront team is working on, but they provide a glimpse into the key goal that the engineers are focused on every day — creation of an amazing place, enabled by “invisible” engineering.

    Kathryn Cox-Czosnyka is a principal project manager at CH2M Hill and project manager for the waterfront consultant team. Andrew Barash is the technical design leader for Seattle’s Waterfront Program and a senior technologist at CH2M Hill.

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