|ZGF Architects - Portland, Oregon’s Simon & Helen Director Park|
|Tuesday, 17 May 2011 08:48|
Director Park presents the first piece of this vision and sets the benchmark for quality materials, complete street design and urban watershed management. After decades of sitting dormant as an asphalt surface parking lot in the heart of downtown Portland, private initiative stimulated the development of this sophisticated piece of urban infrastructure. By shifting zoned development capacity from the Director Park site to the adjacent site to the north, the City of Portland enabled the design of the first new public park in downtown in more than 25 years.
The design is intended to create new open spaces with a variety of microclimates, amenities, and places for activity that present a unique destination and landmark for residents and visitors. A key feature in the park is an open, glass-and-wood canopy sitting high along the street’s edge, offering covered seating space and views over the plaza.
European piazzas were an inspiration for the design of the park. The concept of an urban hardscape stretching from building face to building face allows the park to engage the active street fronts of the adjoining properties.
With the park’s close proximity to Pioneer Courthouse Square, also known as Portland’s “living room,” the more intimately scaled Director Park was designed to act as a complementary “parlor” or “sitting room.” This juxtaposition provides two public spaces that accommodate a balancing array of functions and programs.
The design concept was the result of a collaborative process among the public, the design team, and the City of Portland Department of Parks and Recreation, the Department of Transportation, and the Water Bureau. The process spanned several months and included significant public input at an open house, multiple visioning sessions, and numerous conversations with the City of Portland Design Review Commission.
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Building on an Existing Structure
The existing garage below Director Park placed a number of constraints on the project. The site’s eleven-foot grade change coupled with a need to maintain six inches of undisturbed gravel over the uneven garage lid (to help ensure the integrity of the existing waterproofing) required innovative solutions to incorporate sub-surface utilities and accommodate the maximum ADA-allowed cross slope of two percent. While the finish grades are nine feet above the lid at the south end of the site, they literally are on top of it along the north edge. The fact that the existing garage was designed to support a 375-pound-per-square-foot maximum plaza load meant that areas requiring more than 36 inches of fill had to utilize a combination of rigid foam block and a lightweight soil mix to stay within limits. Finding a lightweight soil mix that would also support trees added a layer of complexity to the project’s design.
The garage portion of Director Park was completed by TVA Architects under a separate contract. To ensure both projects would ultimately come together as one, ZGF and TVA collaborated on the placement and material selection for the two shafts supporting the garage’s stair and elevator access.
Canopy & Art
The dramatic glass canopy is an organizational element that realizes a number of conceptual and programmatic functions.
The glass canopy is supported by a steel post and beam structure topped with a series of purlins. The purlins are a composite assembly of back-to-back wood glulam beams sandwiched around a series of steel boxes. The patterning created within the purlins emulates the pattern created in the plaza stonework and provides a zone to mount and conceal the LED light fixtures and their associated wiring and drivers. The decision to use wood for the purlins was driven by a desire to reflect the regional architecture of the Pacific Northwest.
Open from breakfast through after-dinner drinks and desserts, the café activates the park from early morning well into the evening, seven days a week. The 1,000 SF café provides both indoor and outdoor seating and features a walk-up window for “grab-and-go” drinks and snacks. Outdoor seating consists of a series of fixed benches crafted from Ipe hardwood along with a number of loose tables and chairs that park patrons can configure as desired.
The café is constructed from an exposed, beadblasted stainless steel structural frame. At the seating area, the frame is clad with clear glass, while the area surrounding the kitchen and support zone is clad with limestone and glass of varying degrees of transparency.
The composition of transparencies around the kitchen provides passersby with glimpses of the workers’ activities without completely displaying the less aesthetically appealing components of a commercial kitchen.
Detailing is accomplished with an unobtrusive style that completely showcases the building’s materiality and assembly. The glazing detail, for example, eliminates the typical window mullion and uses the structural frame to support the glass panels. Structural silicon sealant, hidden from view, is the only attachment between the two.
A number of creative solutions were required to maintain the high percentage of glass at the café’s facades. To meet energy code, cooling is not provided within the building; a combination of passive ventilation and a perimeter rooftop misting system keeps the space comfortable during warmer seasons. During the cooler seasons, a heat pump utilizes waste heat from the parking garage exhaust to warm the space. A perimeter radiant slab and operable windows keep the kitchen functions and the Portland weather from creating condensation on the interior of the glass facades.
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Details and Materiality
The entire park was crafted with a minimalist approach that often required intricate detailing to maintain an aesthetically simple-yet-appealing expression. This approach was carried throughout the various means of construction, allowing the quality and the beauty of Director Park’s materials to be showcased. The skill and dedication of the project’s fabricators and craftspeople were integral to the success of this expression.
Building-Face to Building-Face Paving
The piazza extends across SW Park Avenue and SW 9th Avenue and includes the neighboring sidewalks. Variations in the paving pattern help delineate areas of different use. The typical paving assembly utilizes Gobi granite pavers, measuring 3x18x1.25 inches, placed in a modified interpretation of a herringbone pattern. Thicker 4x8-inch units are set in a standard herringbone in the pedestrian pathways and rotated 45 degrees to the direction of travel in the roadway. All granite is sand-set with zero-tolerance joints. While this installation provided initial challenges, it simplifies future work that may need to take place within or below the paving system.
To maintain the singular look of the paving pattern, a variety of inventive details were required for a number of atypical items; namely, fountain jets required angled holes so that arcing water patterns would not be affected, vaults called for thin-set bricks that reduced the load on their access panels, and drainage weirs are spanned with custom grates equipped with spacers that hold the pavers in place. These and other custom details required close collaboration between the designers and the installers.
At Director Park all stormwater is filtered on-site using natural vegetation to cleanse and reduce the amount of solids entering the river. This process also slow the rate at which the run-off is allowed into the city’s stormwater system. Beginning with the canopy, the low point of the structure supports a continuous stainless steel gutter perforated by a series of cables that act as rain chains directing water to a flow-through planter. Also, the café is topped with an ecoroof consisting of sedums, grasses and sage plants to cleanse run-off before directing it to the storm sewer. In addition, the plaza and the streets use the natural slope of the site to direct run-off to street planters and tree wells for filtration.
In the future, this stormwater may be collected and stored to support the irrigation needs of plants during dry months. Director Park was part of a redevelopment study that looked at improving nearby O’Bryant Square and Ankeny Plaza. One of the recommendations of the study is to store filtered stormwater for all three parks at O’Bryant Square. Director Park was designed to support this recommendation, should it be implemented in the future.
Director Park presents one of the first implementations of curbless street design in the City of Portland. The curbless environment physically integrates the streets with the adjacent pedestrian zones. Borders of street trees and stainless steel clad bollards keep motorists and pedestrians from wandering into other zones. For special events, the lack of curbs allows pedestrians and adjacent storefronts to utilize the sidewalk and street as one.
SW Park and SW 9th streets are the only elements that connect the three open spaces that currently make up the Mid- Town Park Blocks. In an effort to reinforce this connection it was deemed a priority to give them an identity different than that of the typical Portland street. In addition to the unique materials and drainage systems employed at Director Park, street furniture is updated and a new light fixture has been introduced. The new fixture not only provides a visual cue that this block breaks the status quo, but it also offers improved performance not available in the typical light standard currently used on Portland’s streets. The new fixture is more efficient, provides a better quality of light, and reduces pollution of the night sky by eliminating uplight.
To address the street and support the on-the-move patron, a walk-up counter was included at the southwest corner of the café. To accommodate this function within the vocabulary of the cafe’s architecture, ZGF integrated a custom overhead door. When closed the door is an integral part of the steel-and-glass composition of the facade. When open it becomes an awning that demarcates the counter and provides protection from the rain. Turner Exhibits, with ample experience in designing and fabricating what it terms as “movable architecture,” collaborated with ZGF on the installation of the water-jet cut steel armature powered by electric actuators that rotate and lift a portion of the cafe’s facade.
To encourage alternative modes of transportation and endorse the bike-friendly attitude of Portland, more than 20 bike racks are spread throughout the site. Director Park is also adjacent to a MAX Light Rail stop, making travel to and from Director Park simple for Portland residents and visitors.
Project details and credits:
Owner City of Portland
|Last Updated on Tuesday, 24 May 2011 16:30|