New York Times:
Security at Symbol of Resolve: Many Demands on New Ground Zero Tower
By GLENN COLLINS and DAVID W. DUNLAP
Published: June 7, 2005
Once intended as a shimmering, soaring declaration of political resolve and architectural ambition, the Freedom Tower at the site of the World Trade Center is being reimagined as something more impregnable. So the challenge now faced by its designers is to keep it from looking like a high-rise bunker.
The Freedom Tower may end up with a structurally massive base that is distinctly different from the upper office floors. The designers may use stainless-steel cladding, reinforced glass or even translucent concrete, a new material embedded with strands of glass that transmits light and shadow through seemingly impervious walls.
The redesign, ordered by Gov. George E. Pataki last month in response to security concerns raised by the New York Police Department, will add tens of millions of dollars to the building's estimated $1.5 billion cost. Less than four weeks before the governor's deadline of the end of June, details of the redesign are still being worked out, said Silverstein Properties, developers of the Freedom Tower and 7 World Trade Center, and Skidmore, Owings & Merrill, the architects of both buildings....
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If antiterrorist security had been the one and only consideration at the trade center site, the first designs for the Freedom Tower and other projects would seem to flout some basic axioms put forth by the Defense Department, the Federal Emergency Management Agency and the American Institute of Architects.
In publicly available reports, they advise that attention-getting architectural symbols are prime targets and should be located far from potential vehicle-borne bombs; glass facades can be lethal in a blast; train stations and underground garages are especially vulnerable to attack; and spacious, column-free interiors under other structures may be liable to collapse....
http://www.nytimes.com/2005/06/07/nyregion/07security.html?pagewanted=all