In November 2003 architect Michael Arad learned that his proposal for the World Trade Center Memorial was among eight finalists selected by the 911 Memorial jury. In a series of meetings with the jury, he was encouraged to refine the design of the memorial and to collaborate with a landscape architect. Arad turned to PWP Landscape Architecture to assist in the design the memorial. Many sketches over the next several weeks led to it being selected the winner on January 5, 2004. The winning features include two gigantic voids, centered on the locations of the destroyed twin towers, in a language similar to Michael Heizer's “North, East, South, West”, the voids render absence visible and give permanent presence to the overwhelming losses of September 11th. The square voids measure two-hundred feet along each side, and cut thirty feet into the site with dramatic waterfalls. The names of those lost in the 1993 and 2001 attacks are displayed at the perimeter of the two voids.
The plaza surrounding the voids is designed to accomplish four main objectives: to deepen and enlarge the visitor’s perception of the level plane into which the voids are cut; to participate in the procession, both physical and spiritual, that is essential to the visitor’s experience of the memorial; to separate the reverential mood of the memorial from the busy life of the surrounding city streets; and to provide a quiet, beautiful, and human-scaled public open space for Lower Manhattan. The coupling of the ever-evolving grove of majestic oak trees, with Arad’s deeply symbolic (but severe) memorial pools is a mixed marriage. This design pairing—and the inherent tension between life and death—of a historic memorial together with a future renewal at the heart of it, is the foundation of the success of the memorial. The trees make it habitable and human. Very simply, the basic notion is that of a forest in downtown Manhattan to communicate rebirth.
To accomplish these goals on a relatively small and irregular site, a forest of hundreds of deciduous white oaks with elongated trunks will be planted irregularly along a regular series of east-west lines. The design establishes an ordering system that originates from the inside of the park. The layout of the trees themselves is at once cultivated and naturalistic, formal and organic. Viewed east-to-west, the oaks are arrayed along a tightly defined grid punctuated by granite slabs to create a boulevard feel. Viewed north-to-south, however, the planting is randomly placed as in a natural forest. Above the limbed-up trunks, a canopy of leaves provides the rebirth in spring, welcome shade through the heat of the summer, and seasonal color in the fall. In the winter the sun casts shadows through a light tracery of bare branches. The flat plane of the park is visible in its entirety through the trunks of the trees. Their mass extends the apparent depth and size of the plane, yet softens the view of the immense buildings and the street life beyond. Over time, the trees are expected to reach a height of sixty-five to seventy-five feet with their soaring canopies growing together to create a cathedral-like appearance when viewed east-west and a fulsome forest from the north and south. The species chosen creates a vaulted ceiling structure, evoking a religious architectural feel, while also mimicking the archways or tridents of the first three stories of the fallen World Trade towers themselves. By stopping before the voids, the trees reinforce the aspect of emptiness and loss.
The plane is defined by paving bands running east-west with large stone slabs, one-foot by five feet in dimension, alternating with small stone cobbles of the same material amid low plantations of grasses, mosses, and groundcover. At the entry points to the plaza as well as around the voids, the ground will be almost entirely paved in stone, providing a smooth, safe, and comfortable surface. Beyond the heavily trafficked areas, the ground will gradually open up, giving way to predominantly planted surfaces, soft to the eye and identifying the memorial’s second nature as a park. The site will always remain a memorial, but as 9/11 fades beyond living memory, it will increasingly serve more as an urban park than a memorial.
The entire plaza surface and drainage infrastructure is designed to function as a large self-sustaining cistern. Water from rainfall and snow melt is channeled into large holding tanks and re-used to support the memorial forest via a specialized drip irrigation system. The forest of over four hundred white oak trees also introduces over 40,000 tons of new soil on the seven-acre memorial site and surrounding streets.
Well in advance of the establishment of a streetscape team, PWP was commissioned by Silverstein Properties to establish a design framework for the entire World Trade Center District’s public spaces. With the design for towers 2, 3, and 4 well ahead, we nonetheless established detailed elevations for all of the future streets and sidewalks, building lobbies and the Memorial. Existing and proposed underground utilities and infrastructure, including the existing subway box, were analyzed and negotiated to create a final surface design for use of the team being selected by Port Authority of New York and New York.
As an important example of this rebuilding effort, PWP developed a complete design for Cortlandt Way to be an important pedestrian connection aligned with the Memorial. The significant grade change leading down to the Memorial has been incorporated to amplify the view through the Memorial trees and into the South Tower Pool. Built with finely detailed stone pavements, stone seat walls with retail and dining terraces, it will service the needs of office workers, and visitors to the Memorial.
Collaborating Firms: Architect: Michael Arad (Handel Architects) Architect of Record and Associate Architect: Davis Brody Bond Pavilion Architect: Snøhetta Arborist: Paul Cowie & Associates Civil Engineer: Parsons Brinkerhoff Concrete and Structural Soil Contractor: Navillus Electrical Contractor: Five Star Electric Fountain Designer: Dan Euser Waterarchitecture Geotechnical Engineer: Mueser Rutledge Irrigation Designer: Northern Designs (Mike Astram) Lighting Designer: Fisher Marantz Stone Mechanical/Electrical/Plumbing Engineer: Jaros, Baum & Bolles Paving Consultant: Mark Smallridge & Associates Plumbing Contractor: 4 J’s Site Metal Supplier: Skyline Soil Scientist: C.R. Dixon & Associates Stone Supplier: Port Morris Tile & Marble Structural Engineer: WSP Cantor Seinuk Sustainability Consultant: Viridian Energy & Environmental Tree Care Consultant: Bartlett Tree Experts Tree Installation Consultant: Kelco Landscaping Tree Relocation Consultant: Environmental Design Vector Control (rodents): Global Environmental Options (Stephen Frantz)