A Vast Invisible Structure to Support a Place of National Remembrance
The site is delineated by a landscaped Memorial Plaza containing two fountain pools, entitled ‘Reflecting Absence’. These 200ft x 200ft pools, which occupy the footprints of the original Twin Towers, are etched with the names of all those who died in the attacks. Beneath the park, descending as far as 70ft below the plaza level, is the museum, which contains hundreds of recovered artefacts. The museum is built up against the original slurry wall that held back the Hudson River on September 11 – this is now designated a federal landmark, and is one of the museum’s most dramatic exhibits.
We provided structural engineering services to deliver the memorial and museum. The design and construction of this hugely significant and sensitive project was a very challenging task, considering the vast scale and complexity of both the plaza and the large space below. The 30ft-deep reflecting pools and waterfalls were designed to very strict standards and are an integral part of the overall structure. The plaza itself rests on heavy steel framing, which also forms the roof of the museum and chiller plant. This structure supports up to 6ft of landscaping soil, allowing the park to be lined with trees. The subterranean museum, meanwhile, required concrete shear walls up to 4ft thick, socketed up to 15ft into bedrock, to resist lateral pressure from the surrounding earth.