Containing debris and providing a safe worksite were the key goals of the Despe Top-Down demolition system, a self-contained, six-story metal cocoon that can hydraulically lower itself around a tower as the structure is demolished floor by floor. But when Despe Managing Director Stefano Panseri was approached by a New York City steel erector that wondered if the cocoon could go up instead of down, he and his team rose to the engineering challenge.
Torre dé Roveri, Italy
ENR 12/11/17 p. 8
Engineer adapts tower-demolition cocoon for a tower-construction job, accelerating the project and improving safety.
Today, a Despe Kokoon envelopes the site of One Manhattan West, a tower currently going up in New York City’s Hudson Yards development. The tower eventually will rise to 70 stories over Manhattan’s West Side, and steel erector Metropolitan Walters expects to use the six-story cocoon the whole way up. “Other cocoons I’ve dealt with are a nightmare,” says Metropolitan Walters’ main superintendent, Steve McAward. “This one is, push a button and go.”
The cocoon itself consists of six stories of walkways and steel-mesh fencing, with guardrails and ladders built in. The entire system is suspended from the building’s structural columns; as those columns are erected, the cocoon can hydraulically jack itself up to follow the ironworkers. Walkways automatically retract during the transition, and the cocoon’s 220 hydraulic jacks are run from a single control cabin mounted to the outside. According to Panseri, the system can perform a double-floor jump in only three and a half hours with only three technicians on site.
In addition to the added safety of preventing debris from falling off the site, the cocoon provides a safe staging area: For example, ironworkers can make steel connections while standing on the walkways, rather than leaning precariously over the beams. Adapting the system for steel erection, rather than demolition, has opened up the possibilities for Despe’s cocoon, and Panseri relishes the opportunity to customize it for new situations.”We have to personalize [the cocoon] for each project,” he explains. “It’s like Lego.”