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Shedding Weight

Today’s public rail facilities acknowledge train depots’ passive-design past while further lessening their impact on the environment


By David Sokol

During the Philadelphia Flower Show earlier this year, visitors and commuters were treated to a soft sell in eco-friendly living. Like so many rolls of flocked wallpaper, moss decorated vertical surfaces of the Market East Station and nearby Transit Museum. Commissioned by the Southeastern Pennsylvania Transportation Authority (SEPTA) and installed by artist Edina Tokodi, moss-sheet cutouts provided a background for signage and formed wayfinding icons. They complemented action-galvanizing posters linking public transit and sustainability. They read: “Riding SEPTA helps lower greenhouse-gas emissions by 50 percent,” as well as, “Riding SEPTA helps reduce smog-forming pollutants by 90 percent.”
Shedding Weight
Photo © Holger Knauf/Ingenhoven Architects
When Ingenhoven Architekten’s design of the new Stuttgart central train station is completed in 2016, its roof will cascade downward in 28 places. These “light eyes” admit daylight and control heat and exhaust buildup.

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The public artwork and posters are clever, but were they effective? The advertising was deployed among Philadelphians who had already chosen to travel greener via public transit. SEPTA was preaching to the converted.

In the way that this ridership campaign encourages consumers to live even more environmentally responsibly than they do—as train riders, they were on their way to an eco-mindset—an analog can be found in many transit authorities’ relationship to green architecture. As the stewards of a conscientious method of moving people, transportation agencies are beginning to consider how they may fulfill their eco-missions more completely. Further, they are constructing new facilities that embrace sustainability with enthusiasm, despite the tight budgets that typically accompany public works.

It wasn’t always this way, says Rob Quigley, FAIA, an architect with offices in San Diego and Palo Alto, Calif., who completed the Escondido Transit Center and Solana Beach Transit Station in California in the early 1990s, prior to the burgeoning popularity of sustainable architecture. “The difference in the way we do things now and 10 years ago is the client,” he says. “That we were thinking about proper shading and overheating was our concern as responsible architects, but that wasn’t part of the conversation with the community or client.”

For the Escondido project, Quigley moved all circulation outdoors and shaded it with palm trees and latticework, while the Solana Beach facility’s greenhouse form not only makes reference to the region’s agriculture but also admits daylight. Quigley notes, “The fact that most people are passing through these buildings rather quickly means it doesn’t have to be 71.2 degrees, 24 hours a day. That works nicely with concepts of passive energy conservation.” Back then, the architect merely took advantage of a benign climate. Today, he earns green kudos.

Despite clients’ previous limited engagement with the subject, the history of transit buildings is a history of quietly sustainable design. “One interesting thing about the building type is that it’s probably done better than most building types in terms of daylighting,” Quigley says. For example, the sunny train shed in St. Pancras, completed in 1877, was relaunched last November as the London terminus of the Eurostar train that links that city to Paris. More recently, although budget cuts have removed sidewalk-embedded skylights from the World Trade Center transportation hub and, in July, forced architect Santiago Calatrava to close up the hub’s centerpiece wings, those wings will still form a daylight-filled atrium for the PATH terminal below.

Indeed, as public-transit clients think more seriously about their image and their responsibility to lower life-cycle costs for taxpayers and the planet alike, contemporary solutions nod to this legacy of daylighting and one-up it. New York’s famous Coney Island neighborhood, for example, is home to the Stillwell Avenue Terminal, an AIA/COTE Top Ten honorable mention in 2007. For the reconstruction of this 90-year-old facility, Brooklyn-based architect Kiss + Cathcart clad the 76,000-square-foot structure’s two low, broad arches in thin-film photovoltaics. One of the largest PV arrays in the U.S., it produces 250,000 kilowatt-hours of energy per year. The roof also is punctuated by narrow rows of clear glass to ensure that sufficient daylight reaches the subway platforms.

Another celebrated example of innovation in the building type is Melbourne’s Southern Cross Station, designed by Grimshaw, with local practice Jackson Architecture, and completed in 2006. The 646,000-square-foot facility serves as a terminus for regional rail service, a bus node, and a pedestrian link between the city’s central business and Docklands districts used by more than 15 million people each year. It is distinguished by an undulating, square-block roofscape that covers the activity.

There’s good reason that the Southern Cross Station roof resembles dunes: Its asymmetrical moguls were generated by digital modeling that took into account the area’s prevalent northwest and southwest winds. Hot air and train and bus fumes collect in the domed underside of the moguls and are exhausted via louvers crowning each of these domes. By making the roof’s shape sympathetic with local wind patterns, natural ventilation whisks away exhaust more quickly. Spine trusses are covered with ETFE—the inflated polymer pillows that famously clad the PTW-designed National Aquatics Center, or Water Cube, constructed for this summer’s Olympic Games in Beijing—to enhance this flying carpet’s illusion of weightlessness and to admit daylight to the station’s transient occupants.

Ingenhoven Architekten’s scheme for a new main station in Stuttgart, Germany, which won Holcim awards for green design in 2005 and 2006, will update the shed into an even more multifaceted sustainable building. Replacing a Paul Bonatz-­designed terminal that has stood proudly in the city since its completion in 1928, the building instead will nestle 12 meters below grade, its rooftop allowing the green axis of Stuttgart’s linear park, Schlossgarten, to continue over it once the new station is completed in 2016.

The roof contains the forthcoming building’s most notable feature, an innovative take on the skylight. Developed with Frei Otto and Buro Happold, the 1,400-foot-long poured-concrete shell is punctuated by 28 “light eyes” developed by modeling using computational fluid dynamics. At each of these circular openings the roof appears to cascade downward, touching the train platforms in the form of a tapering structural column that supports the shell. Besides providing sufficient daylight without causing overheating, grilles located at the top of each light eye further allow heat and exhaust fumes to escape from the space below.

Fred Clarke, FAIA, makes a special point that the natural ventilation so carefully featured in designs like Ingenhoven’s and Grimshaw’s are not just flourishes but rather necessary strategies for coping with a harsh reality of public transit: emissions. “Public transportation is not in itself green—their fleets are among the most polluting vehicles. Although it’s greener than having millions of cars on the road, only if the public-transit vehicles themselves were electric, hybrid, very low emissions, or biodiesel would I ever characterize public transit as genuinely green,” says Clarke, one of the founding members of the New Haven-based firm Pelli Clarke Pelli Architects (PCP).

It’s that perspective that, in September 2007, won PCP the commission to design the Transbay Transit Center and Tower in San Francisco. Envisioned by the local transportation authority, the Transbay Joint Powers Association (TJPA), as the anchor of San Francisco’s redeveloping Rincon Hill neighborhood, the transit-center component of the complex will shelter buses and a future high-speed rail terminus, while an adjacent 1.7 million-square-foot tower will rise 1,200 feet. Construction crews should begin digging foundations in 16 months.

“It delighted our client,” Clarke says of telling TJPA CEO Maria Ayerdi-Kaplan that “what she did not want is to inadvertently build another Port Authority in the middle of San Francisco.” He was referring to the midtown Manhattan bus terminal in which idling buses spew particulates and emissions into nearby residential neighborhoods as well as the western edge of the Times Square tourist district. To prevent the Transbay building complex from the same fate, PCP plans to subdivide the building into vehicular and pedestrian parts, with different air-change requirements; currently, it is figuring how to integrate HEPA-like filters throughout the bus zone. Moreover, the 5.5-acre roof of the transit center has been conceived as the largest park in San Francisco after Golden Gate Park: It was structurally reinforced to support the intensive plantings—tall broadleaf plants, specifically—that do the best job of trapping pollutants from the air, so it was not a huge leap to allow people to access the roof too. In addition, the building’s hyperbolic paraboloid column clusters serve as five-story light wells. PCP is also studying synergies with the center’s adjacent tower, such as drilling wells underneath the transit center to heat and cool the tower through ground-source heat exchange and reusing graywater from the tower to irrigate the transit-center park. 

The Transbay Transit Center and Tower exemplifies the alacrity with which public-transit clients rally around sustainability today. “Her mandate to us is to explore any and all ideas as long as they are beneficial to the transit center,” Clarke says of Ayerdi-Kaplan. It also underscores the combinations of green strategies that are defining a new generation of train depots. Yet, Clarke says there’s still a ways to go, emphasizing that real sustainability means perfecting vehicles and the buildings that house them.

Tangible projects and near-future dreams, though not dedicated to rail travel, may bring that necessity to fruition. The HOK-designed Santa Clarita Transit Maintenance Facility, for example, features fuel stations for city buses powered by compressed natural gas and straw-bale office buildings. In Norman Foster’s scheme for the new 50,000-resident city in Abu Dhabi called Masdar, people zip around in an underground personal rapid transit system powered by the sun. With greater public will, perhaps achieving Clarke’s vision of unassailably green public transportation is only a matter of time.

David Sokol is a New York-based freelance writer and a regular contributor to Architectural Record and GreenSource magazines.

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This article appeared in the September 2008 print issue of GreenSource Magazine

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