Twenty-five years after the September 11 attacks, two additions to the World Trade Center campus give permanent form to the symbols and ideas that emerged from the site’s destruction and reconstruction.
A 13-foot-tall memorial unveiled Sept. 8 in Liberty Park transforms an image worn on the helmets of Port Authority of New York and New Jersey workers during reconstruction into a three-dimensional monument. A second installation, announced Sept. 9, sits on the floor of the Oculus, the centerpiece of the $4 billion World Trade Center transportation hub, the path of sunlight that helped shape Daniel Libeskind’s original master plan to redevelop the 16-acre site.
From the helmet to the Memorial
The monument’s circular granite base recreates part of a 1995 Port Authority memorial to employees killed in the 1993 attack on the World Trade Center that was destroyed on 9/11.
Image courtesy of HNTB
The Port Authority Employees Memorial, near St. Nicholas Greek Orthodox Church and overlooking the World Trade Center Memorial Pools, honors the 84 agency employees killed on September 11, 2001 and the six killed in the February 1993 World Trade Center bombing. The Port Authority said it is also recognizing those sickened or killed by illnesses related to post-9/11 recovery work.
The non-profit World Trade Center Memorial Fund commissioned and installed the sculpture in partnership with the Port Authority. Its design is based on a perspective image of the Twin Towers that became a symbol of remembrance and recovery among agency workers, appearing on helmets, patches and flags after the attacks.
HNTB served as architect and engineer of record. Project manager Thomas Grassi said the central challenge was to translate the image’s two-dimensional, forced-perspective aerial view into a structure recognizable from below, but also able to “stand alone architecturally and meaningfully” for visitors unfamiliar with the original symbol. The team tested the geometry with digital and 3D printed models.
The towers are constructed of stainless steel, supported by 316L stainless steel plates welded in a box configuration. The 2,300-pound stainless steel segment is attached to granite elements with grouted anchors, bringing the entire memorial to about 25,000 pounds. It rests on a 9-inch thick concrete pad over compacted dense aggregate and existing geofoam. Kearny Sheet Metal Works manufactured the stainless steel and Burns Bros. & McCabe Inc. he made the stone.
“When standing at the monument location, a person feels as if they are on the ground, but this location is actually the roof of a vehicle facility,” Grassi said.
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HNTB studied the framing, capacity and waterproofing of the World Trade Center’s below-grade vehicle security facilities before determining that the memorial could be placed there. The team also evaluated various crane installation locations so that erection could occur during a limited overnight construction window, minimizing impacts to nearby streets and an adjacent hotel.
The granite also links the new memorial to one that stood at the original World Trade Center. It came from the same quarry that supplied stone for a Port Authority memorial inaugurated in 1995 to those killed in the 1993 bombing. This memorial was destroyed on 9/11. The new structure recreates its circular ring with red inscription. According to Grassi, it is the first memorial that brings together the employees of the Port Authority killed in the two attacks in the same place.
Grassi spent 30 years at the Port Authority and was working on the 82nd floor of One World Trade Center when the first plane hit on 9/11. He spent the next 15 years working on recovery and reconstruction, wearing the symbol of the Twin Towers on his helmet throughout that work.
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A design drawn in sunlight
Inside the Oculus, the Port Authority has installed permanent floor markings aligned with Libeskind’s “Wedge of Light” concept.
A Lasa marble and glass centerpiece and inscriptions that stretch across the Oculus trace, according to the Port Authority, the axis and angle of the sun between 8:46 a.m., when American Airlines Flight 11 hit the North Tower, and 10:28 a.m., when the tower collapsed.
The new floor markings on the Oculus trace the angle and path of the sun associated with Daniel Libeskind’s “Wedge of Light” concept for the reconstructed World Trade Center site.
Image courtesy of PANYNJ
An inscription records the sun at an azimuth of 128.45° and an altitude of 41.33° at 10:28 am. An anti-slip glass covers the marble medallion.
When Libeskind’s “Foundations of Memory” concept was selected in February 2003, ENR reported that the plan included a “wedge of light,” then envisioned as a plaza around an intersection within the World Trade Center site.
When Santiago Calatrava unveiled his conceptual core design in 2004, ENR reported that his retractable roof was intended to admit daylight into the structure, including sunlight corresponding to September 11, 2001.
In 2006, ENR reported that Calatrava wanted to change the traffic hall to incorporate part of Libeskind’s Wedge of Light plaza, a change that eventually won agreement from Libeskind, the Port Authority and government officials.
Calatrava told ENR that year that he saw the transportation hub as potentially becoming a “living memorial,” a place where people would arrive at the World Trade Center through light and activity. The center was located within the Wedge of Light garden plaza, with the building sloping along its southern edge.
This emphasis on light extended to an operable roof designed to open annually on September 11, allowing natural light and a portion of the sky to enter the building. The Oculus, which opened in 2016, had fixed wings after a redesign.
The new foot medallion marks the 10:28 AM position with an inscription: “HERE IS THE SUN AT 10:28 SEPTEMBER 11, COMPLETING A WEDGE OF LIGHT.”
