Building at World Trade Center is a showcase of terrorproof technologies

Architects around the world are erecting skyscrapers that use a hollow concrete core surrounded by bomb-resistant glass and other security innovations.

from the February 4, 2008 edition

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Old Wall Street buildings, forming the "canyons" of 1930s-era high rises, often choke off the signals for legions of BlackBerrys, and just aren't built for the high-tech business needs of today. In 10 years, Mr. Silverstein believes, Wall Street firms will head a few blocks west to Greenwich Street, near the World Trade Center site, leaving the historic business district to the luxury loft renovators. But first he must convince them these state-of-the-art buildings are state-of-the-art safe.

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The sense of security architects tried to build into the hollow spine of 7 WTC, which has tenants on 30 of 42 available floors, starts with the glow-strip lined stairs. Stadiumlike in size, the stairwells allow a space where evacuees can rest or the wheelchair-bound can wait for assistance. They are also pressurized to force out smoke, and engineers have incorporated dual standpipes and extra water storage for the sprinkler system.

But beyond the concrete core, 7 WTC has a host of other security features. The building's skin is made almost entirely of glass, and since the foundation is designed like a diamond parallelogram, the structure gives off a crystalline appearance – hardly the look of a concrete bunker in the sky.

The glazing process incorporates new bomb-resistant technologies into the glass that eliminate flying shards – and actually shield the structure from an explosion, deflecting the energy of a blast. Windows are double-paned, laminated, and layered with a new plastic polymer. The windows near the lobby are reinforced with inner cables that would, like a rubber band, absorb a blast and snap back.

The lobby features another use of "new" glass. A 65-by-14-foot art installation behind the reception desk doubles as a bomb shield for the elevator lobby. The installation has two laminated glass walls. Each wall is a series of vertical panes that tilt inward, like a giant hinge, and spring back in the event of an explosion. Designed by James Carpenter and conceptual artist Jenny Holzer, the display flashes illuminated poetry and prose.

"It's quite robust in its strength, although it's relatively delicate in terms of its visual presence," says Mr. Carpenter, a sculptor and architect at James Carpenter Design Associates here.

Throughout 7 WTC, architects have tried to convey openness and optimism rather than a fortress mentality. Even the first eight floors, which are windowless and house a utility substation, are wrapped in a stainless-steel screen that glows a faint blue after dusk. The wall contains light sensors that create a drifting illumination whenever a pedestrian walks near it. "We're always trying to harness two things," says Carpenter, "performance and visual aesthetics."

Indeed, as four larger towers begin to rise at Ground Zero, architects in a post-9/11 world must balance safety with art, commerce, and community interests. "There's no doubt in anyone's mind that as they're building these towers," says Hauser, "somebody overseas is thinking about how to take them down again."

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