By Chelsea Hedquist, HowStuffWorks.com
A Symbol of Hope and Safety
The gaping void left behind when the Twin Towers came down on Sept. 11, 2001, has become as symbolic today as the towering structures that once filled the space. Ground Zero evokes devastating scenes that have been seared into the nation's collective consciousness, but rebuilding Ground Zerooffers New York City and the country a chance to create a new symbol — one of hope and triumph in the face of tragedy. With this weighty task at hand, the Port Authority of New York & New Jersey has taken steps to ensure not only an impressive end result but also a safe construction zone that never echoes the terrifying scenes of 9/11. The safety cocoon — a novel safety system among Manhattan's skyscrapers — plays an important role in this effort.
Snug As a Bug — at 1,776 Feet
It doesn't take a structural engineer to understand why the safety cocoon makes sense. Upon its completion, One World Trade Center will reach 1,776 feet (541 meters) into the air, making it the tallest building in North America. But skyscrapers don't build themselves. Large teams of ironworkers erect the steel framework at dizzying heights. As if the safety of the workers on the building doesn't create enough worry, falling tools and equipment can also present a serious hazard to workers on lower levels or the ground. The safety cocoon aims to lessen fears on both counts.
Made from fire-resistant netting, the fully installed cocoon spans 20 floors. Steel-framed netting encases the top four floors, while protective netting continues to wrap the building for an additional 16 stories. Platforms interspersed throughout the netting offer workspace, as well as enhanced protection in case of falling workers or equipment. The cocoon continually gets raised to the top floors of the building as construction progresses, ensuring the greatest safety at the greatest heights.
As the blue nets of the safety cocoon rose at the site of One World Trade Center in May 2010, Port Authority Executive Director Chris Ward said in a press release, "There are a lot of innovative firsts on this [World Trade Center] site, and this state-of-the-art system ... will set a new standard for workers and public safety in skyscraper construction throughout the city."
But this high standard comes with a hefty price tag — the Port Authority paid DCM Erectors $9 million for the safety cocoon.
Sending a Sky-high Message
Those millions actually get the Port Authority a sky-high billboard, as well as a state-of-the-art safety system. The cocoon provides "a unique communications opportunity," as the Port Authority's director of World Trade Center construction Steve Plate called it at a board meeting. The Port Authority plans to display its logo and the website wtcprogress.com on the netting. But the cocoon's bright blue netting will, itself, provide the clearest message and a visible reminder that the builders at Ground Zero spare no expense when it comes to safety. In a country where, according to the U.S. Bureau of Labor Statistics, an average of five construction workers die on the job each day — and at a site that holds the memories of one of the most frightening episodes in the nation's history — this message will surely resonate with both workers and onlookers.
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