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April 19, 2012

Structural design lends flexibility to rental car firms

  • The Port of Seattle’s facility is part of a new generation of long-span moment-frame garages.
    KPFF Consulting Engineers


    The Port of Seattle’s Consolidated Rental Car Facility is a world-class project that expands the port’s ability to provide travelers with exceptional service.

    As structural engineers for the entire facility, KPFF was involved in the design and construction process, providing key leadership at critical times during the development. KPFF worked with the port and the design team to meet the goals of flexible space, expressive architecture, durability of surfaces and quality of finishes.

    The RCF encompasses more than 45 acres of usable space as it provides parking for more than 5,400 rental cars. This concrete giant is easily seen from the new Sound Transit airport light-rail system as it anchors the southeast corner of the airport expressway to the state Route 518 intersection. Located on this 24-acre site between state Route 99, the Airport Expressway and Route 518, this facility is essential to the smooth flow of passengers to and from the airport.

    The project is comprised of 14 independent structures plus thousands of feet of roadway and retaining walls. Excavation of 350,000 cubic yards of hillside opened the way to creating a five-level facility that sits extremely low in the landscape.

    Photo courtesy of KPFF Consulting Engineers [enlarge]
    The port had 350,000 cubic yards of hillside excavated to give the five-level RCF a low profile.

    The main parking facility is composed of six independent structures. Cars and buses navigate the site via four bridges. Vertical circulation for rental vehicles is accomplished with two compact helical ramps that also serve as a backdrop for public art. Routine vehicle preparation is performed in the four quick-turnaround facilities.

    Flexibility of space

    The RCF is part of a new generation of long-span moment-frame garages designed to create flexibility for rental car companies. The long-span structural frame touches lightly on the operational floor plates, which allows each company to configure the floor to meet their operational needs.

    The operational areas of the building were specifically designed without concrete shear walls. This allows free vehicle movement across the floors. The basic building bay module, measuring 60 by 36 feet, greatly reduces the amount of columns in the operational plates.

    A two-way long-span moment-frame system resists earthquake loads while allowing wall-free spaces up to 790 by 490 feet on each level. This 9-acre open floor plate is the essential ingredient which allows this high level of flexibility.

    Some floors are dedicated to a single company while others are shared based on fleet sizes. Each rental car company is able to program its allocated floor area to meet its specific operational needs with minimal structural intrusion. Common use areas — the customer lobby, escalator cores and helical ramps — are designed to minimize structural intrusion and allow each company to share equally.

    Expressive architecture

    With its soaring wing-shaped roofline, the 60,000-square-foot customer-service building rests lightly upon the fifth level of the concrete structure and provides a home for all the rental companies’ lobbies. This space may be shared by more than 10 companies, each with its own branding and identity. This expansive space was created by using a light steel roof with main spans of 60 feet.

    The roof structure perches atop large round columns with an architectural cap detail intended to emphasize the lightness of the roof itself and create a feeling of the roof floating above the space. The beams and girders of the roof, exposed outside of the building envelope, become the architectural signature of the patron experience as they arrive to get their rental cars.

    Durability of surfaces

    Rental car facilities are 24/7 operations. Sea-Tac’s RCF will deploy and retrieve more than 10,000 cars a week. Cars are moved and processed quickly, which can create wear on anything not specifically designed for the rigorous environment. In order to create a low-maintenance facility that is forgiving, heavy reinforced concrete was exclusively used on the operational floors.

    Special detailing of steel and concrete reduces incidents of impact damage while creating long-term value for the owner by lowering maintenance costs. Wall-free operational floors eliminate blind spots and minimize potential contact points between cars and the structure, thereby reducing wear and tear.

    Quality of finishes

    This building has exposed structure on more than 90 percent of its area including all operational floors, exterior parts of the customer-service building and throughout the quick-turnaround facilities. Exposed structural elements include cast-in-place concrete floors, ceilings and walls, as well as exposed steel framing and architectural features.

    Selective use of architectural ceilings and soffits creates people spaces within the expanse of the overall facility. Finish quality, including structure and architectural materials, are focused on the port’s goal of creating a world-class facility to enhance the traveler’s experience.

    Long road, great finish

    Final design was originally awarded in 2001. Since then the RCF has survived several major hurdles, some of which suspended design and one which temporarily halted construction. To ensure continuity throughout the design and construction period, KPFF maintained key structural and civil engineers on the project from start to finish.

    Rarely does a working facility of this size grace such a prominent location. The port’s vision of a world-class facility has been realized within a rental car facility that is a tour de force of serviceability with a functional aesthetic that enlivens as well as anchors the northeast corner of the airport.

    Craig Olson is the structural engineering principal in charge of the Consolidated Rental Car Facility. Olson leads the design of transportation facilities including rail and bus stations, parking structures and maintenance facilities in the Northwest for a wide variety of public agencies.

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