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Tempe Transportation Center; photographer © Bill Timmerman
 
Resilient cities need infrastructure that lasts and planning teams that are willing to step up to the plate. Designing structures that can sustain decades of use requires forethought beyond the basic combination of blocks, steel and glass. Just like sidewalks and street corners, city buildings have the power to connect people to one another. Buildings are shelters from unpredictable weather, places where people can have a good time or sit quietly and think. Buildings can also serve as checkpoints or another step in someone’s journey from point A to B.  

Developing cities that thrive through the ebb and flow of time are not simply about creating infrastructure that can persist, but about designing buildings that evolve as cities evolve. Sustainable design transforms as cities develop visions for furthering connections among neighborhoods and city sectors. Design features such as energy efficiency, water conservation, and heat reduction that better regulates a building’s temperature are significant elements that replenish a city’s vitality through buildings that are capable of adapting to a city’s needs. Infrastructure that is greater than the sum of its parts also requires infrastructure that functions according to the changing needs of residents.

The Tempe Transportation Center in Tempe, AZ located at on 200 East Fifth Street at the base of Tempe’s A-Mountain is the City’s central multi-model space. This Center is the hub for a variety of public transit like the METRO light rail, the regional and local Valley Metro buses a free neighborhood shuttle bus called Orbit, the Bicycle Cellar ( a local bike rental and repair shop), and retail space.

One of the most striking features is the way the building has been constructed to adapt to the City’s needs for approximately 100 years. The longevity of the structure is depicted in its fundamental design plan. The plan focuses on combining resilient building materials with the natural benefits of a desert environment to create heat and water systems that are more energy efficient and spaces that provide natural sunlight and shading. The Center serves as an educational space, highlighting how city buildings can not only be more energy efficient, but also better integrated into the surrounding environment. The 40,000 sq. ft. design features were chosen by a collaborative team led by the architectural firms of  OTAK and Architekton, Tempe’s transportation staff, City Council, the LEED consultant Natural Logic Inc., landscape consultant A Dye Design, and public artist Lorna Jordan. Designed to be 52% more energy efficient than other buildings of its kind, the center is considered to be the first major sustainability focused design project in Tempe.

The Tempe Transportation Center development process is a great example of effective inter-departmental cooperation. Since the center was initially proposed to be the first building in Tempe to gain LEED 2.1 certification, one of the main challenges in developing such a new project was getting other departments and decision makers comfortable with the various design requirements and regulations. In the project’s early phase, an informational meeting was assembled to share the goals of the project and get opinions from the City Councilmembers, department officials and the city staff. The meeting consisted of a half-day presentation on the center’s design, as well as a half-day workshop, which facilitated a discussion on the various challenges and solutions to developing a LEED Platinum certified building.

Continued inter-departmental collaboration on the project helped to create an urban space that can easily change as the City and regional public transit system continues to develop. The design is also a testament to how important it is to consider a myriad of viewpoints including cultural perspectives. The planning team worked with Native American stakeholders who view the Hayden Butte as a sacred site. To integrate this perspective into the overall design, the three-story building was pushed to the western boundary to protect scenic views of the mountain.

 

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View of A-Mountain from the center; photographer © Bill Timmerman
 
The Center’s Structure:

Sustaining the scenic view of A-mountain prevented the center from being developed with the optimal east-west orientation. Various alternative shading strategies were used to mitigate sun exposure. On the east side of the center, 18 motorized adjustable shades are programmed to deploy at dawn and retract at noon. On the west side, the façade is opaque masonry, designed to delay and reduce the transfer of heat to the interior. Other sustainability features include a 15,000 gallon stormwater recovery system and a grey water system recycles water from the showers, sinks and water fountains.

Planning for mixed-use development is essential when creating a space that links the present needs of city residents to future uses. The Tempe Transportation Center consists of three floors. The third and second floor house the Transit Operations Center and the Tempe Transportation Office, as well as for-lease tenant office space, while the first floor focuses on Transit Oriented Development (TOD) housing retail space and the Bicycle Cellar.

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Tempe Transportation Center Floor Plans; Photo courtesy of Architekton
 
The Bicycle Cellar is a well-chosen addition to the transportation center since Tempe contains a large bicycling community including commuters and Arizona State University (ASU) professors and students. In order to find a collaborator for the bicycle facilities, a Request for Qualifications (RFQ) was sent out to advertise the opportunity locally. Currently, the Bicycle Cellar includes:
  • double decker bike racks imported from Germany,
  • space to rent general and elliptical bikes, sell bikes and repair bikes, and
  • four changing rooms and bathrooms that include showers

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 Double decker bike racks; Photo courtesy of OnetrackWheelMan
 
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One of four shower/changing rooms; Photo courtesy of The Bicycle Cellar

Acclimating to the Desert Environment:

With approximately 296 days of sun per year and average high temperatures reaching 105°F during summer months, some of Tempe’s most significant design concerns are reducing interior temperatures resulting from extreme heat. The Tempe Transportation Center features heat reduction strategies that provide the City with a resilient transit oriented landmark that bonds community and economic growth in the surrounding areas.

The community room is one feature in the center that pays tribute to how Arizona residents used to acclimate to the desert environment. The north and south glass walls of the community room open to create an elevated gathering space which allows cool air to flow more freely. The room is inspired by the historic “Arizona Room”, a common design feature used before the advent of air conditioners. The common room rests on supporting columns which form a ground-level plaza providing permanent shade through all seasons, enhanced with seating, landscaped beds, and gabion walls filled with recycled glass slag and multicolored LEDs. 

The Center’s green roof, a first in Arizona, is used primarily to keep harmful ultraviolet rays from damaging the roof’s membrane. As an essential aspect of reducing heat from permeating the building, the roof consists of four different native plants, such as bear grass and rocky point ice plant, selected due to their ability to exist in the Sonoran desert climate. In full bloom, the roof plants display a variety of textures and form, organized within a grid design that duplicates the character of the Center’s east elevation.

 

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The newly planted roof garden; photographer © Bill Timmerman

A series of experiments were carried out over a two year period at Arizona State University (ASU) to decide the correct ratio of sand, mulch, moisture and soil amendment. It was decided that the soil should be 8 to 12 (more than the standard 4 inches) to protect the plant roots from intense heat on an arid desert urban roof.

Drip irrigation provides minimal hydration the low water use plants. Besides protecting the roof membrane from severe summer temperatures and ultraviolet degradation, the roof system also filters rainwater and supports the local habitat for birds, bees and butterflies. A typical roof in Arizona usually lasts less than 20 years, and often requires patching and repair. The Sarnofil roof system has been installed and in use in Europe for 50 years without replacement.

Working alongside the history of the desert landscape, the center’s visionaries had to accommodate archeological digs and excavations. An anticipated six to eight week archeological investigation turned into a process of investigation and documentation that was not fully complete until 2012. Findings include ancient structures (walls, floors and hearths) that were occupied from 500 to 1450 A.D. Contractors adapted to this surprise discovery by working around the active exploration and beginning construction on a portion of the site that had already been excavated.

The Tempe Transportation Center has developed within the constraints of the City’s planning codes and regulations in effect 2004. Although this is a substantial achievement driven by inter-departmental collaboration, determining when existing policies have become outdated is also an important element to include in an urban planning toolkit. Updating older regulations and policies so that they accommodate new technological and design solutions facilitates more mixed-use and infill development in the Phoenix metro area and the state.

To encourage residents to feel emotionally invested in their city’s infrastructure, buildings need to be designed to fit into the city’s future framework. Resilient cities need infrastructure that coalesces with residents’ needs and supports new sustainable design initiatives. What makes the Tempe Transportation Center’s story significant is that the design strategy contains not only technological concepts that complement the local climate, but also pro-actively prepares to fulfill residents’ future public transit needs and their investment in public buildings that will last far into the future. Creating new buildings and maintaining older ones with the idea of longevity and flexibility helps encourage residents to care about how their city’s structures relate to neighborhoods and city streets. Infrastructure that supports neighborhood connectivity while being energy efficient is the backbone of a progressive, sustainable city.  Buildings that have the design flexibility to evolve as their cities evolve support community interests and help to build more resilient communities.

For more information on the Tempe Transportation Center contact:

Bonnie Richardson, bonnie_richardson@tempe.gov, 480-350-8628