Most of the world's tall buildings, called skyscrapers, are in the United States. However, the recent terrorist attacks have caused some Americans to worry about the safety of these extremely tall buildings. I'm Steve Ember. And I'm Sarah Long. We tell about the future of skyscrapers today on the VOA Special English program, THIS IS AMERICA.
For almost thirty years, the World Trade Center stood more than four-hundred-ten meters above New York City's financial center. The two towers of the Center were the tallest buildings in the city. They had more than one-hundred levels. Then on the morning of September Eleventh, two hijacked airplanes struck the buildings.
Many people died immediately in explosions and fires. Others ran down many levels of steps in an effort to escape the buildings. Others waited for help in their offices. Then, one after another, both buildings fell. The collapse of the towers killed thousands of people. It also wrecked or damaged surrounding buildings.
Engineers from the state of Illinois soon will investigate the collapse of the buildings for the Federal Emergency Management Agency. Their early study, however, shows that the buildings held up well. One tower remained standing for about forty-seven minutes after the plane hit it. The other tower stayed up for about one hour and forty minutes after it was struck. The fact that the towers stayed up as long as they did permitted many people to escape.
Several experts have said no building could have resisted the attacks. The terrorists meant to cause the largest explosions and the hottest fires possible. So they hijacked planes heavily loaded with fuel. The heat from the burning fuel weakened the steel structure of the towers. These fires burned far hotter than fires used to test building materials. They also burned longer. The intense heat caused the upper levels of the buildings to fall. Then the lower levels also fell.
Some pieces of building wreckage caused destruction in the area. Mainly, however, the towers imploded – fell down in their own space. Several engineers praised the World Trade Center for this. Many more people would have died if the buildings had fallen to the side.
Officials say the wreckage will take months to clear. After the attacks, broken glass and smoking metal lay twelve meters above the ground. The World Trade Center had contained two-hundred-thousand tons of steel. It also had forty-three-thousand windows.
About fifty-thousand people worked in the World Trade Center. Some estimates say as many as ninety-thousand people passed through it on some days. The towers represented business and trade in the biggest city in America. Many people throughout the world recognized pictures of the World Trade Center against the skies of New York.
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People in New York are discussing ways to remember the World Trade Center and the people who died in the attack. Several artists and building designers suggest a memorial called "Towers of Light." The arts group Creative Time proposes forming two towers of light in the shape of the fallen buildings. These lights would reach toward the sky. The artists currently are researching methods that could produce lighting with such power.
Businessman Larry Silverstein currently controls use of the World Trade Center property. Mr. Silverstein says he will rebuild the Center. However, it is unclear what the new Center will be like.
Some architects have suggested creating four shorter buildings. These structures would have about fifty levels. A park between the buildings would contain a memorial to victims of the attack.
Other New York citizens called for rebuilding the World Trade Center as it was. For example, former Mayor Ed Koch urged replacement of the two skyscrapers. He said this would show the terrorists that New York remained undefeated.
However, some city planners believe such extremely tall structures should not be replaced. Instead, some experts advise copying other New York buildings that are not as tall.
The Urban Land Institute is a research and educational organization for planners and building designers. Some members believe skyscrapers waste space. These experts say some buildings use their lower levels mainly to get people to the upper levels.
Some experts also believe the office needs of businesses are changing. Most large companies now have their headquarters in skyscrapers. This permits their employees to work together in one place. However, employees today can communicate easily though electronic mail and other technology. So some planners believe there will be less need for skyscrapers in the future.
The Empire State building is now the tallest building in New York City. It was built in Nineteen-Thirty-One. It was the tallest building in the world for more than forty years. It still is one of the most popular. Thousands of millions of visitors have seen New York from observation areas in this building.
Some Americans now say they are worried about the Empire State Building. However, a wealthy New York property owner has offered as much as fifty-seven-million dollars to buy it. He says he believes fear of skyscrapers will be temporary.
Many of America's skyscrapers have increased safety measures since the terrorist attacks. Owners have placed barriers around the buildings at street level. Security devices and guards examine people who enter the buildings. Building occupants are receiving information about what to do in an emergency.
Skyscrapers were invented in the United States. As early as the Eighteen-Eighties, two new technical developments made these taller buildings possible. One development was the mechanical elevator. It meant that people would not have to climb many steps to reach the upper floors of tall buildings. The development of steel also helped make taller buildings possible.
The first skyscraper was built in Chicago, Illinois in Eighteen-Eighty-Five. The Home Insurance Building was almost fifty-five meters tall.
Chicago became home to the world's tallest building in Nineteen-Seventy-Three when the Sears Tower was built. It is four-hundred-forty-two meters tall. The Sears Tower was the tallest building in the world for twenty-three years. Then, in Nineteen-Ninety-Six, two taller buildings were completed. They are the Petronas Towers in Kuala Lumpur, Malaysia. They are about four-hundred-fifty-two meters tall.
Recently, businessman Donald Trump proposed another very tall building for Chicago. Mr. Trump and the owners of the Chicago Sun-Times newspaper wanted to build a structure four-hundred-fifty-seven meters high along the Chicago River. Mr. Trump and the newspaper owners have been seeking more money for the project. Now, however, it is unclear if they will continue proposing such a big skyscraper.
Developers in China want to build the tallest skyscraper ever. They are planning an International Financial Center for Shanghai. The Center is to be more than four-hundred-eighty-seven meters tall.
The building would have several safety measures not included in the World Trade Center buildings. For example, the areas containing steps would be wider than those in the World Trade Center. Areas called refuge floors would be placed every ten to twelve levels. These open-air places are designed to protect people from smoke. They are legally required in China and some other Asian countries.
Experts say there is almost no engineering limit to the height a skyscraper can be. Still, people's feelings may limit the size of skyscrapers in the future.
For example, a New York City stock trader works in an office high in a skyscraper. He says he once liked to look out his office window and see the other tall buildings of the city. But his feelings have changed since the terrorist attacks.
Now, he says, he would like to work much closer to the ground.
This program was written by Jerilyn Watson. It was produced by Cynthia Kirk. I'm Sarah Long. And I'm Steve Ember. Join us again next week for another report about life in the United States on the VOA Special English program, THIS IS AMERICA.