NEW YORK: One World Trade Center, under construction here, has not yet emerged from below ground, but its facade has 
already survived earthquakes, hurricanes and an explosion that shook the ground a quarter-mile away.

In recent months, two full-size  mock-ups of a few floors of the glass and aluminum facade have been built and tested. One is 
outside Los Angeles, in Ontario, California. The other was at a site in central New Mexico that can be reached only over dirt roads 
in four-wheel-drive      vehicles.

At 1,368 feet, or 417 meters,  with 23 acres, or 9 hectares, of glass-clad  surface area, 1 World Trade Center will be subject  to 
tremendous natural forces. The building, also known as the Freedom Tower (at a symbolic 1,776 feet, when its mast is counted), 
will be the tallest in New York City and as the skyscraping phoenix on the site of ground zero, it may be the target of terrorist attacks, 
too.

The Port Authority of New York and New Jersey, which is building 1 World Trade Center, and Skidmore, Owings & Merrill, which 
designed it, said both mock-ups had performed well.

The first was subjected to a blast test in Socorro, New Mexico, at the Energetic Materials Research and Testing Center,  a division 
of the New Mexico Institute of Mining and Technology. Because details might arm a prospective attacker officials would say almost 
nothing about the test of this mock-up. "The simple answer is, yes, it passed," said John McCullough, the project executive for the 
Port Authority.

He was more forthcoming about the tests last month at Construction Consulting Laboratory West in California. There, a $537,000 
mock-up was built to represent a corner of three typical tower floors, with laminated glass panes 1.5 inches, or 3.8 centimeters, thick. 
The largest are 5 feet by 13 feet and weigh half a ton.  An enclosed steel chamber was constructed behind  the glass and aluminum 
cladding.

The goal was to find out how  much air and water leakage could be expected under storm conditions that could be expected at least 
once in 50 years. Water jets simulating winds of 74 miles per hour, or 119 kilometers per hour, were sprayed at the facade.

An earthquake was simulated by jacks pulling the mock-up in different directions.

McCullough said the mock-up met all the performance criteria. Fox said: "Sometimes on these tests, you have to do forensics and 
do corrections. Here, we had no failure at all."