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Landscaping collects, processes, and filters runoff from impervious areas and trackways to ensure no stormwater leaves the site of TriMet's new light rail terminus. Photo: Ambient Light

PROJECT: South Terminus turnaround

OWNER: TriMet, provider of bus, light rail, commuter rail, and streetcar services for metropolitan Portland, Ore.

DESIGN TEAM: Hennebery Eddy Architects, Lango Hansen Landscape Architects, and public artist Bill Will

CONSTRUCTION COSTS: $2.6 million

When it was built in the 1970s, Portland's transit mall was studied and imitated nationwide. It consolidated regional bus traffic serving the city and the surrounding tri-county area on a one-way couplet of two major streets running through the densest area of downtown. While some automobile traffic was permitted, the mall was predominantly reserved for buses and transit stops. It was also at the center of Fareless Square, an area of downtown where bus transit was free to encourage short trips by bus rather than personal vehicles.

The design was a key part of a larger strategy that, along with limiting parking in downtown and the availability of lower-emission vehicles, permitted the EPA to lift air quality sanctions it had placed on the city.

Thirty years later, residents and visitors are able to reach downtown Portland by light rail as well, via a new route — the Green Line — that runs over the Willamette River and along the transit mall before ending at the South Terminus. A little larger than a city block, this train turnaround area includes two structures housing equipment, a power traction substation, and a signal communications building. Highly visible from the hills surrounding the city, the new rail line delineates Portland State University's campus from downtown proper.

Designed to generate 50 kW of energy from the sun and another 10 kW from wind, the terminus is TriMet's experiment in integrating renewable energy into transit infrastructure. Just as the original mall did, this project could spawn imitations in other cities.

The project posed significant design challenges, however, which included city guidelines that don't permit prefabricated structures, providing space for the agency to add new rail lines, and allowing for future development of adjacent sites by the university.

For example, TriMet usually locates power traction substations, which power the trains, and signal communications equipment, which controls train operations, in two separate buildings made of brick or concrete masonry with metal roofs. Rather than commit project funding to embellishing two small buildings on the site, the design team led by Hennebery Eddy Architects suggested incorporating the equipment into a single larger structure: a sculptural steel framework covered with photovoltaic panels and coil drapery that would screen the equipment from public view while supporting the photovoltaic installation.

This solution serves two purposes: It generates renewable energy while doubling the agency's investment in solar technology by using the photovoltaic panels as an architectural element rather than in the traditional rooftop application.

The form of the photovoltaic structure footprint is based on the layout of future rail alignments. Arranged in seven facets and totaling approximately 350 panels, the panels are a hybrid bifacial module on a semitransparent surface that allows light to filter through. The eastern edge of the screen will cantilever over the sidewalk and provide opportunities to explore the inner workings of the support system while forming a pedestrian gateway at the downtown edge of the site.

Funding for the overall photovoltaic structure is being provided through the American Recovery and Reinvestment Act of 2009. Because the project's renewable energy components were conceived and developed after most of the mall's renovation had been designed, budgeted, and contracted, funds for the entire South Terminus project weren't allocated in the original budget. After exploring several funding strategies, including cost-sharing agreements with third-party energy developers and local utilities, TriMet decided to develop and own the renewable energy components itself.

Thus, design, construction documents, regulatory approval, and final construction pricing for the framework and drapery were complete — but not funded — when the stimulus package was signed. The agency successfully applied for a $1,106,043 grant through the Federal Transit Administration's Transit Investment in Greenhouse Gas Reductions (TIGGER) program, which funds capital investments that reduce the energy consumption or greenhouse gas emissions of public transportation systems. The money is enabling the sculptural framework and coil drapery screening material to move forward in 2009.