The true story of the twin towers blown up in New York, and what they actually symbolized

Fifteen years ago, on September 11, 2001, the World Trade Center complex was blown up in New York. 2996 people died, over 10 thousand were injured of varying severity. Both twin skyscrapers (Twin Towers) ceased to exist. Another building of the complex - the Marriott Hotel - was buried under the rubble of the first tower. The frames of the four others survived, but they were deemed irreparable and demolished.

Idea

The idea of \u200b\u200bbuilding the World Trade Center (WTC) in Manhattan back in the late 1950s was made by the famous billionaire brothers David   and the former mayor of New York Nelson Rockefellers. They were supported by the local Port Authority. The construction of the complex began in 1966 and, according to some estimates, cost $ 1.5 billion.

WTC Skyscrapers Designed by American Modernist Architect Minoru Yamasakiwho is believed to have won the competition because he offered to build towers quickly and cheaply. He worked with Antonio Brittaiochi   and Emery Roth & Sons. Before proceeding with the construction of two giants of steel, glass and concrete, Yamasaki created hundreds of models. Perhaps he felt that the most grandiose and modern construction in the world at that time would become his swan song and therefore tried to express his idea in it. “The WTC should be a symbol of faith in the power of man,” the architect said more than once.

When creating the project, Yamasaki mixed his Gothic addictions and architectural and ethical ideas of the great Le Corbusier. Subsequently, some critics called the architecture of the WTC towers limited and boring, and the scarcity of form, in their opinion, served as an "indicator of an internal catastrophe." Someone considered these buildings the personification of the existing social system in the United States.

When the first of the colossi appeared in New York, critics called him "the biggest finger in the sky." A specialist in technical history Lewis Mumford regarded Twin Towers as "an example of unintentional gigantism and technological exhibitionism, which is now gutting the living tissue of every big city." Many did not like the narrow (only 46 cm wide) windows of the office premises of the towers. According to the then prevailing judgments, the architect made them so, because he was terribly afraid of heights.

However, it was believed that the skyscrapers of the World Trade Center personified a man and a woman. In confirmation of this, it was pointed out that Yamasaki emphasized the male tower with an elastic antenna, and the female one with a gateway to the observation platform. He and She were, as it were, moving towards the Hudson and all of America. The woman, as always, was half a step behind. Perhaps it was an architectural image of Adam and Eve leaving Paradise? The architect himself definitely did not speak out about this.

Design

To clear a place for grandiose construction in the area of \u200b\u200bthe city port, dozens of low-rise buildings were demolished. 1.2 million cubic yards of land was taken out and taken out to create a foundation under the skyscrapers of 21 meters deep and Plaza - an underground space where later there were shops, restaurants, banks, airline ticket offices, travel agencies, a new metro station, workshops for serving twin towers , warehouses and underground garage for 2 thousand cars.

When constructing the skyscrapers, an engineering idea was used, which was first applied when creating the IBM office center in Seattle. In this case, the designers also applied a structural model of a rigid "hollow pipe" from closely spaced columns with a diameter of 990 mm, with trusses of floors 83 cm thick expanding to the central part. Many steel columns were inside the building and became the supporting part that held the entire building. In this case, complex steel floors served as stiffeners. Such a concept made it possible to create inside the spacious, not cluttered with unnecessary constructions of space.

The facade of the buildings with a width of 64.5 m was a prefabricated steel grate with columns with a width of 476.25 mm. They protected the entire structure from wind and other external overturning loads. The location of the "wind supports" outside the surface of the building prevented the transfer of forces through the membrane of the floors to the center. On each of the four sides of the building along the entire height was 61 steel beam. Between them along the entire height of the cables were pulled. They, as well as a package of cables inside the elevator shafts, provided design flexibility. In general, the towers were a combination of steel cages from the modules produced at the plant with a size of 10x3 m and a weight of 22 tons. The external columns of the buildings were finished with silver aluminum alloy. This gave the impression that there were no windows at all in the skyscrapers. Although there were as many as 43 thousand.

The twins were the first ultra-tall buildings designed without masonry. They developed a special “dry-wall” system, fixed in a reinforced steel base. The floors were supported by a series of light trusses on rubber panels located between the outer columns and the elevator part. Both "brothers", according to the designers, were able to withstand a hurricane wind and had to withstand even in the case of a ram with a medium-sized aircraft, such as a Boeing 707.

They were built mainly of glass, steel and concrete using duralumin and durable titanium. In total, about 400 thousand cubic meters were needed for construction. m of cement, 200 thousand tons of steel and 20 thousand square meters. m glass.

Exploitation

The first tower was built by 1970. But officially the WTC in New York was opened only on April 4, 1973 after the second was commissioned. The complex included five more ground facilities. Among them are the high-rise Marriott Hotel, the commodity exchange and the 8-story American Customs Palace. Eight floors in both high-rise buildings (7–8, 41–42, 75–76 and 108–109) were technical. All the rest, with a total area of \u200b\u200bmore than 1 million square meters. m, rented out.

The height of the WTC skyscrapers (North Tower - 110 floors, 417 m, South - 104 floors, 415 m) was at that time a constant topic of jokes and jokes. Here is one of them. At a press conference after the WTC opening ceremony, Yamasaki was asked: “Why are there two buildings with 110 floors? Why not one in 220? ” His answer: "I did not want to lose the human scale."

In the 1990s, 10% of all lower Manhattan offices were located in the towers of the World Trade Center. There were offices of almost 500 companies. So, in the South Tower, 25 floors under the head office were rented by Morgan Stanley, the investment company of $ 487 billion, the Oppenheimer fund with "modest" $ 125 billion was managed over 5 floors. Four floors housed Fuji Bank . 3 floors were occupied by the New York Stock Exchange, AON insurance company, Verizon telecommunications company (capitalization of $ 17.5 billion), Manciani Duffi architectural firm (recognized as the best interior designer in 2000) and Thacher, Proffit & Wood Law Firm .   Modestly, only 2 floors each, had the Sun Microsystems computer corporation, the New York State Department of Tax and Finance, and the Frenkel & Co insurance agency.

On a typical day, 50 thousand employees and 200 thousand visitors and tourists came to work at the WTC. On the 107th floor of the North Tower there was a fashionable and expensive restaurant “Windows to the World”. There, Americans loved to celebrate weddings and celebrate various significant events. In the 1990s, tens of thousands of tourists daily climbed the observation deck of the South Tower. On a clear day, through the fence from suicides, they could survey the surroundings within a radius of 78 km.

The system of 99 elevators in the skyscrapers was arranged in such a way that from below the high-speed elevators went to the beginning of the 2nd and 3rd sections of the building, starting on the 44th and 78th floors. From there, "local" elevators lifted passengers to the desired floor. Each intersection elevator could lift 55 people at a speed of about 8.5 m per second. In total, the WTC complex had 239 elevators and 71 escalators, which were controlled by a computer center. Window washing in two towers took place automatically 3 times a week using special machines on steel movable cables.

Destruction

The great constructive advantage of the New York twins was that the steel beams of the buildings were connected to the supports located less than a meter from each other, forming the exterior walls of the building. While the vertical supports of most other American skyscrapers are located at a distance of 6 m from each other, and the main load in them is transferred to the combined diagonal racks, the damage of which, as a rule, leads to the immediate destruction of the entire building.

And the disadvantage was the lack of foam fire systems that could cope with burning aviation fuel. Concrete is guaranteed to withstand flames for an hour or two. But 91 thousand liters of aviation fuel, which were used to fuel both aircraft sent by the terrorists to the WTC buildings, turned winged cars into thermal bombs. When the combustion temperature exceeded 800 ° C, the steel supports began to melt. However, later it was discovered that the main reason for the collapse of the Gemini was not this.

A few years after the tragedy, experts unequivocally established that the cause of the collapse was a gradual displacement as a result of a fire in the buildings of the center of gravity. External columns could not withstand extraordinary stress.

Oleg Klimov

(based on foreign press)

REFERENCE: Minoru Yamasaki —   American architect who combined international style with neoclassical features. Born in Seattle, USA, December 1, 1912 in a Japanese family that had American citizenship.

In 1949 he founded his own company. In 1951, he received an award from the American Institute of Architecture for a residential complex in St. Louis, USA. True, already in 1972, these buildings were destroyed as "morally obsolete and socially burdensome."

Among the most famous buildings designed by Minoru Yamasaki are the US Consulate in Kobe, Japan (1955), Lambert Airport in St. Louis, USA (1956), McGregor Memorial Community Center in Detroit, USA (1958), and Dahran Airport, Saudi Arabia (1961) and the airport of the Eastern Province in Riyadh (1985).

He built skyscrapers and at the same time was panicky afraid of heights. Working on the WTC buildings, Minoru Yamasaki divorced his wife, married another, then divorced again and married, then again. In the end, he divorced again and returned to his first wife.

Construction thursday August 25, 1966 - Wednesday April 4, 1973 Using wednesday April 4, 1973 - Tuesday September 11, 2001 Height Antenna / Spire 1 WTC: 526.3 m. Roof 1 WTC: 417 m.

2 WTC: 415 m.
  3 WTC: 73.7 m.
  4 and 5 WTC: 36 m.
  6 WTC: 32 m.
  7 WTC: 186 m.

Top floor 1 WTC: 413 m.

2 WTC: 411 m.

Technical specifications Number of floors WTC 1 and 2: 110 floors

3 WTC: 22 floors
  4 and 5 WTC: 9 floors
  6 WTC: 8 floors
  7 WTC: 47 floors

The area inside the building WTC 1 and 2: 400,000 m 2

4, 5, and 6 WTC: 50,000 m 2
  7 WTC: 170,000 m 2

Number of elevators 239 Architect Minoru Yamasaki

Emery Roth and Sons

Owner Port Authority of New York and New Jersey

World Trade Center   (eng. World trade center), abbr. The WTC is a complex of seven buildings designed by Minoru Yamasaki, an American architect of Japanese descent, and officially opened on April 4, 1973 in New York (USA). The architectural dominant of the complex was two towers, each of 110 floors - Severnaya (417 m high, and taking into account the antenna installed on the roof - 526.3 m) and Yuzhnaya (415 m high). September 11, 2001 the WTC complex was destroyed as a result of a terrorist attack. For some time after the construction was completed, the towers were the tallest skyscrapers in the world (before that, the highest building was the Empire State Building, which, after the destruction of the WTC, again became the tallest building in New York). Sometimes these towers are called "a symbol of US world domination."

History and construction

View of the window of one of the twin towers. It can be seen that the entire outer skin consists of huge steel rods.

Minoru Yamasaki conceived the World Trade Center project in 1962, in January 1964, an architect commissioned Port Authority to create drawings of buildings, a little later that year he presented for discussion a model in 1: 130 full size, and two years later (5 August 1966) powerful excavators began to dig a pit.

Before the twins, skyscrapers in New York were erected on a natural stone base. Manhattan is really stone, it has stone and granite under a layer of earth, this is seen when you observe the construction of new houses: pits here are not dug up, but they are cut down and gnawed out with steel teeth of cutting hammers.

The first problem that the engineers encountered was that there wasn’t any stone at the place where the twins were supposed to stand. Instead, they discovered artificial, alluvial soil that used to “belong” to the Hudson River. This soil was a large amount of artificial land, mixed with layers of cobblestone, sand, gravel, naked, even old ships came across in artificial soil. The builders were desperate: additional difficulties, additional costs, additional concrete.

This was not the only problem that awaited the architect and engineers. The next problem that befell them was 164 large and small, narrow and wide buildings, most often stone, which stood on the site of the future World Trade Center and had to be demolished. It was not difficult to demolish them, but the problem still remained after that. It was much harder to leave intact and then transfer the rich and complex underground communications system, fire alarm system, multi-core telephone and electric cables, gas, heat, pneumatic and water pipes, not to touch the expressway passing nearby and save numerous pedestrian roads and transitions.

Another problem was the underground railway station, from here starting an underwater route in New Jersey, which takes to work and takes hundreds of thousands of people out of work. If the road were closed, New York and the entire United States expected inevitable economic problems. The underground transported people until a new underground station was built in the lower tier of the complex.

This is not to say that the work of the builders was easy. That only costs 1.2 million cubic meters. yards of land that had to be dug up and taken out. Instead, under the twins, the so-called Plaza was created - an underground space where numerous restaurants and banks, travel agencies, airline ticket offices, shops, a new station of the New Jersey road, much better than the previous one, storage rooms, technical workshops for servicing twins and an underground garage were located for two thousand cars.

Faced with the difficulty of building a building of unprecedented height, the engineers applied a progressive structural model: a rigid "hollow pipe" of closely spaced steel columns, with trusses of floors expanding to the central part. On the outer surface of each of the four sides of the building, 61 steel beams ran along the entire height, between which cables were also stretched along the entire height. The columns, trimmed with silver aluminum alloy, were 476.25 mm wide and were installed only 558.8 mm apart, which made it seem like from a distance that there were no windows in the towers. The bearing walls were assembled from prefabricated steel blocks, each weighing 22 tons, 36 feet high (4 floors high), 10 feet wide. Two hundred thousand tons in total weighed steel, laid in Gemini.

As the twins grew, installers laid the floors between the special corrugated steel and strong concrete slabs prepared in advance at the plants. The ceilings were attached to the outer load-bearing walls from the outside and to the internal, the only twin steel columns with a purely useful function - they were erected to fix the internal elevators.

The elevator system used in the buildings was also unique. The twin towers were the first ultra-tall buildings designed without masonry. Concerned that the intense air pressure created by high-speed elevators could bend standard shafts, engineers developed a solution using a “dry-wall” system mounted in a reinforced steel base. Elevators with a standard configuration for serving 110 floors could need half the area of \u200b\u200bthe lower rooms for the location of the shafts. Otis Elevators developed a fast and compact system in which passengers had to take turns in the “heavenly vestibules” on the 44th and 78th floors, which halved the number of mines. In total, the World Trade Center complex had 239 elevators and 71 escalators, which were controlled by a computer center from Port Authority. Each elevator with a lifting capacity of 4536 kilograms could lift 55 people with a lifting speed of about 8.5 meters per second.

The foundation laying in the dug pit began from the north tower in August 1968, including by the Italian workers, who started work at 8 in the morning and worked until 15:30 with a 40-minute lunch break at the normal rate, and after half past three they worked at a double tariff: the team leader received $ 40 per hour or $ 80 per hour in the evening, respectively, and overtime was the rule, not the exception. Construction went quickly, despite the difficulties encountered with financing. The budget of New York in 1965-1970. amounted to 6 billion dollars. In order to raise money for investment in the construction of the Shopping Center, the city issued bonds with a guarantee of their repayment. But in 1970, New York suffered a financial crisis. The maturity date for bonds came up. The construction was almost frozen. To save the situation, it was necessary to introduce new, increased taxes in the field of entrepreneurship. Another source of money was found: they began to rent future Gemini premises for offices. And they were expected to be huge - 100 thousand square meters. m. Of all the difficulties finally managed to "get out." The north tower was completed in 1971, the south - in 1973. The grand opening of the World Trade Center took place on April 4, 1973.

The towers were square in cross section, with a side of 65 m. Each tower is 110 floors. The foundations of the structures went 23 meters underground. 200 thousand tons of rolled steel were spent on building frames, and electric network cables, with a total capacity of 80,000 kilowatts, stretched 3 thousand miles - half the distance from New York to London, across the Atlantic. The structure of the buildings was simple and reasonable. The facades are made in the form of steel frames and mounted on them modular aluminum sections 3.5 × 10 m in size, manufactured by the factory stamping method. This design is earthquake-resistant and able to withstand the pressure of the wind, very strong at high altitude. According to the architects, each tower of the World Trade Center could withstand collisions with several aircraft, but on September 11, 2001 both towers of the WTC collapsed to the ground.

Fire February 13, 1975

On February 13, 1975, three fire alarms rang out on the 11th floor of the North Tower. The fire spread through the central empty pipes to the 9th and 14th floors due to the fire of telephone wires in a shaft located vertically between floors. Those areas where the fire penetrated through the wires were extinguished almost immediately, they managed to cope with the fire after a few hours. Most of the damage occurred on the 11th floor, where a fire began in an office filled with paper, liquid for printing machines and other office equipment. The fire treatment of steel against melting saved the skeleton itself, and no structural damage was done to the tower. In second place for the damage caused were the lower floors, which were affected not so much by fire as by fire foam. At that time, the World Trade Center did not have a fire extinguishing system.

Act of terrorism February 26, 1993

Destruction in the basement

February 26, 1993 at 12:17 pm a truck with 680 kg of explosives drove into the territory of the World Trade Center, which was driven by Ramsey Jozef. It exploded in the underground garage of the North Tower. As a result, a hole with a diameter of 30 m was drilled through 5 underground floors, causing maximum damage to levels B1 and B2 in their entire history and significant damage to level B3. Six people were killed (including during a crush at the exit) and another 50,000 workers and visitors could not breathe due to lack of oxygen on 110 floors of the towers. Many people inside the North Tower had to go down the dark stairs, and some took more than two hours.

Jozef fled to Pakistan shortly after the explosion, but was arrested in Islamabad in February 1995 and extradited to the United States for trial. Sheikh Omar Abdel Raman in 1996 was accused of participating in the organization of the explosion and other conspiracies. Youssef and Ayd Izmoil were sentenced to life imprisonment in 1997 for involvement in the explosion. Four others were also sentenced in May 1994 for participating in the explosion. According to the court, the plotters aimed at completely destabilizing the North Tower, followed by the South Tower - that is, the complete destruction of both towers.

After the explosion, it was necessary to restore the affected floors, especially because they carried a structural load and were supporting. The wall of liquid cement after the explosion was in danger, and metal plates were also lost that impeded the pressure of the Hudson water on the other hand. The cooling unit on the B5 sublevel, which supplied air to the entire World Trade Center complex, was disabled.

After the attack, port authorities installed photoluminescent signs on the walls. The fire warning system had to be completely replaced due to the failure of the wiring and alarm system of the original system. In memory of the victims, a reflecting reservoir was created with the names of those killed in the explosion. As a result of the September 11 attack, the memorial was destroyed. A new memorial, common to the victims of the explosion and terrorist attack, will appear in a new complex under construction on the site of the former World Trade Center.

The destruction of September 11, 2001

On September 11, 2001, terrorists hijacked American Airlines flight 11 and made a deliberate collision with the North Tower at 08:46 (from the north facade, between 93 and 99 floors). Seventeen minutes later, a second group of terrorists crashed into the South Tower (floors 77-85) on the same stolen plane of United Airlines Flight 175 of United Airlines. Due to the damage caused to the North Tower by the aircraft body, all exits from the building were completely blocked above the collision site, as a result of which 1,344 people were trapped. The blow of the second plane, unlike the first, fell closer to the corner of the skyscraper, and one stairwell remained intact. However, few people managed to freely descend it until the collapse of the structure. But nevertheless, despite the fact that the plane’s strike on the South Tower fell lower, it turned out to be blocked between floors or less than 700 people died at once - much less than in the North. At 9:59, the South Tower collapsed due to a fire that damaged steel structural elements, already weakened by a collision with an airplane. The North Tower collapsed at 10:28 a.m., after a fire that lasted 102 minutes.

At 17:20 on September 11, 2001, the eastern penthouse of the seventh building of the World Trade Center (WTC-7) collapsed, and at 17:21 the whole building collapsed due to the fact that spontaneous fires irreversibly destroyed its structure. The third building of the World Trade Center, the Marriott Hotel (WTC-3), was hit by the falling Twin Towers. The three remaining buildings of the complex were severely damaged by the fallen debris and were eventually demolished, since they could not be restored.
  The Deutsche Bank building on the other side of Liberty Street, opposite the World Trade Center complex, was later declared unsuitable for people to stay in it due to the high content of toxic compounds in the premises; Now this building is dismantled. The Fitterman Hall of Manhattan Community College on West Broadway, 30, is also destined for demolition due to extensive damage sustained during the attack.

Already after the terrorist attack, the media reported that tens of thousands of people could be affected, since over 50,000 people could be in the complex during normal business hours. As a result of the 9/11 attack, 2,752 death certificates were issued, including in the name of Felicia Dunn-Jones, whose death was registered only in May 2007; Dunn-Jones died five months after the attack due to the terrible state of her lungs caused by clouds of flying dust during the collapse of the World Trade Center buildings. Two more victims were later added to the official death toll list: doctor Sneha Anne Philip, who was last seen the day before the attack, and Leon Heyward, who died in 2008 from lymphoma, provoked by inhalation of dust-saturated air, rising in the collapse of the Twin Towers. Cantor Fitzgerald L.P. Investment Bank, located on the 101-105 floors of the World Trade Center, lost 658 employees - more than any other institution, even the Marsh and McLennan Companies, located directly under the bank's premises on 93-101 floors (where the plane crashed terrorists) and lost 295 people. In third place in terms of loss of life (175 people) - Aon Corporation (Aon Corporation). 343 New York City firefighters, 84 Port Authority of New York and New Jersey employees, including 37 members of the Port Authority Police Department, the Port Authority Police Department (PAPD) and 23 officers of the New York Police Department, also died. Of all the people who were in the towers at the time of their collapse, only 20 people were recovered alive, including PAPD police officers - Will Gimano and John McLaughlin (the eighteenth and nineteenth survivors).

Effects

As a result, all seven buildings of the complex were destroyed: the three highest buildings (North Tower, South Tower and WTC-7) collapsed, the Marriott Hotel was almost completely destroyed by the wreckage of WTC-1 and WTC-2, the other three buildings suffered such damage that they were found unfit for restoration and later demolished. Also, as a result of the collapse of the WTC-2, irreparable damage was caused to the 40-story building of Deutsche Bank, which is currently dismantled.

A memorial complex was erected on the site of the collapsed twin towers.

Buildings of the new complex

• Freedom Tower 1 )
• 200 Greenwich Street (Tower 2 )
• 175 Greenwich Street (Tower 3 )
• 150 Greenwich Street (Tower 4 )
• 130 Liberty Street (Tower 5 )
• World Trade Center Transport Hub

Notes

1. Builders: WTC towers collapsed due to “pancake effect”
2. 9/11 Commission Report. The National Commission on Terrorist Attacks Upon the United States. Archived
3. Dwyer, Jim, Lipton, Eric et al. 102 Minutes: Last Words at the Trade Center; Fighting to live as the towers die, The new york times   (May 26, 2002). Archived from the original on October 10, 2008. Retrieved May 23, 2008.
4. NIST NCSTAR 1-1 (2005), p. 34; pp. 45-46
5. FEMA 403 -World Trade Center Building Performance Study, Chapter. 5, section 5.5.4 (PDF). Archived from the original on August 27, 2011. Retrieved January 30, 2011.
6. Final Report on the Collapse of World Trade Center Building 7 - Draft for Public Comment xxxii. NIST (August 2008). Archived from the original on August 27, 2011.
7. World Trade Center Building Performance Study. FEMA (May 2002). Archived
8. World Trade Center Building Performance Study - Bankers Trust Building. FEMA (May 2002). Archived from the original on August 26, 2011. Retrieved July 12, 2007.
9. The Deutsche Bank Building at 130 Liberty Street Archived from the original on August 26, 2011. Retrieved July 12, 2007.
10. Fiterman Hall - Project Updates. Lower Manhattan Construction Command Center. Archived from the original on August 26, 2011. Retrieved November 19, 2008.
11. DePalma, Anthony. For the First Time, New York Links a Death to 9/11 Dust, The new york times   (May 24, 2007).
12. Official 9/11 Death Toll Climbs By One, CBS News   (July 10, 2008). Retrieved August 29, 2010.
13. Foderaro, Lisa W.. 9/11 "s Litany of Loss, Joined by Another Name (September 11, 2009). Retrieved August 29, 2010.
14. Siegel, Aaron. Industry honors fallen on 9/11 anniversary, InvestmentNews   (September 11, 2007). Retrieved May 20, 2008.
15. Lung Ailments May Force 500 Firefighters Off Job, The new york times   (September 10, 2002). Retrieved May 23, 2008.
16. Post-9/11 report recommends police, fire response changes (August 19, 2002). Retrieved May 23, 2008.
17. Police back on day-to-day beat after 9/11 nightmare, CNN   (July 21, 2002). Retrieved May 23, 2008.
18. In New York, the premiere of Oliver Stone’s film, Radio Liberty   (August 07, 2006). Retrieved March 5, 2011.

see also

• World Trade Center Memorial
• List of World Trade Centers List of world trade centers )

References

• Official website
• Genis, Alexander. September 11: images of the tragedy (about the book: David Friend, Watching the World Change), Radio Liberty   (September 13, 2006). Retrieved March 5, 2011.
• Genis, Alexander. September 11: "Twins Day", Radio Liberty (September 08, 2008). Retrieved March 5, 2011.
• Kopeikin, Anatoly. I’m all looking somewhere in the sky, as if I’m looking for an answer, or an amazing story, Russian thought   (June 06-12, 2002). Retrieved March 5, 2011.

Ultra-tall buildings (see also list of buildings above 100 floors)
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During   building	23 Marina 175 Greenwich Street Ahmed Abdul Rahim Al Attar Tower   Al Hamra Tower Al Yaquob Tower APIIC Tower Central Market Project China 117 Tower DAMAC Heights Diamond Tower Gift D1 Tower Dubai Towers Doha Elite Residence Emirates Park Towers Faros del Panamá

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World Trade Center. New York Twin Towers - Fallen Brothers

New Yorkers called the Twin Towers (Twins Towers) World Trade Center skyscrapers, which were destroyed on September 11, 2001 by a terrorist attack. This event has become a national tragedy for the United States. It was not in vain that the terrorists chose the Twin Towers as their goal, because they were the country's national pride, a symbol of democracy and a symbol of the greatness of the American people. Today, the Twins Taueras reminds us of a huge memorial built on the site of the tragedy. In many Hollywood films released before the events of September 11, we can see the panorama of the City of New York Dream, which is sure to have the towers of the World Trade Center. On tourist postcards of those times, gigantic "twins" were also traditionally depicted. And how many souvenirs were made related to these towers! Unfortunately, now these trinkets are more likely to remind us of the sad:

However, this article was planned not in the form of an essay in memory of the fallen colossi, but rather as a story about an architectural masterpiece that went into oblivion, but nevertheless retained a good memory. It is logical that the project in exactly copying the WTC is not in the plans of the American urban planners. Why strive to repeat success? May the Towers “live” in our hearts.

However, in addition to the memorial in the area once occupied by the WTC, it was decided to build several high-rise buildings. Indeed, not to empty such a tidbit in Manhattan? Already at the construction stage is the skyscraper Freedom Tower, which will have a height of over 500 meters. It will be approximately completed by 2013. In addition to this office building, there are 4 more projects, but so far they only exist on paper. Developed 3 high-rise towers and one residential building. These giants will grow next to the memorial on Greenwich Street.

Before starting the story about the Twins Towers, we give a little explanation. The World Trade Center was actually a complex of seven buildings, which included the unfortunate North and South Towers. Each of the towers contained 110 floors, but the height varied - at the South Tower it was 415 meters, and the North - 417. Nearby was the 22-story Marriott Hotel, which had the short name WTC-3. Three more buildings of WTC 4-6 consisted of 9 floors, and in WTC-7, located across the road from the rest of the complex, contained 47 floors.

Construction history

The idea to build a grand skyscraper was born in the postwar years. The US economy was actively reviving after the recession caused by World War II. In the 50s, most large companies had their offices in New York, namely in Manhattan. An influential businessman David Rockefeller, taking advantage of the guarantee of his brother Nelson (who served as governor of the city), suggested starting here the construction of the World Trade Center. The project was supported by the Port Authority of New York and New Jersey. The entire project was led by the Manhattan Creative Association, whose head was just David Rockefeller. It was assumed that at the WTC, upon completion of construction, there will be about 4% of the city’s office property.

  For some time, the project remained only in the minds of its associates, but at the end of the 50s the WTC began to work closely. This was mainly due to the political situation in the country. The citizens of the United States in those years markedly diminished belief in the further development of democracy and the country's prosperity. It was then that the authorities decided to bring to life Rockefeller’s ideas, taught the World Trade Center “under the sauce” of a national project. According to authorities, a gigantic complex could rally the entire people of America around itself. Famous architects vied to offer their designs, but gave preference to the development of Minor Yamasaki. This American architect of Japanese origin was the author of many beautiful rear, including: the airport in St. Louis, the Concrete Institute, the Institute of Arts and Crafts in Detroit. Together with Minoru Yamasaki, architect Antonio Brittechi, as well as Emiri Roth and Sons, worked on the WTC concept.

In 1964, commissioned by the Port Authority, the first drawings of future twin towers were created with a 130-fold decrease, and on August 5, 1966, construction of skyscrapers began.

From the very first days at the construction site, various technical problems began to arise. On the site of future construction was not stone, but artificial soil, which is a mixture of cobblestones, sand, and naked. Therefore, the construction of the Twins Tower foundation required much more concrete than originally planned; this circumstance resulted in a sharp increase in construction costs.

Then it was necessary to solve a difficult engineering and technical problem. At the site of future skyscrapers, it was necessary to demolish about 160 buildings, but at the same time preserve all engineering communications (gas pipeline, water supply, sewage, electric cables, etc.), as well as the nearby high-speed highway and road network.

Another important problem was the underground railway line running at this place. It was impossible to close it, because every day tens of thousands of people traveled through the subway to work and home. The authorities decided not to lay alternative transport routes, as this would further increase the cost of building towers. Therefore, the line of the New York subway functioned until a new one was launched, with a station in the lowest tier of the WTC complex.

During the construction of the Twins Tower, more than 1.2 million cubic yards of land had to be removed from the ground. The educated foundation pit became not only the foundation of the twin towers, but also the Plaza was organized in it, which is a huge space that housed a car park for 2000 cars, a new underground railway station, restaurants, offices of various companies, banks, warehouses, shops and etc.

According to the plan proposed by Minor Yamasaki, the Twins Tower were to become not only the tallest skyscrapers in the United States of America, but also the world. And this meant that the Twin Towers should be given a higher height than the Empire State Building, which at that time firmly held the palm of the largest building on the planet. An interesting engineering solution was invented for this. In fact, the towers were a very strong hollow metal pipe created from columns with trusses for floors. Along the walls of the building was located 61 beams of special steel. Each column had a diameter of 476.25 mm, they were installed tightly to each other. The distance between the beams was only 558.8 mm. The weight of each such steel block was as much as 22 tons, and the height was 4 floors of the future building! In total, about 210,000 tons of heavy-duty steel were consumed in the construction of skyscrapers. The floors between the floors were made of concrete slabs and corrugated steel, which were attached to the supporting elements of the entire structure. Inside the buildings, steel columns were erected for future elevators.

  The twin towers were the first building in the world without the use of masonry, and engineers were afraid that high air pressure could disrupt the normal operation of elevator shafts. Therefore, a special engineering system was developed for elevators, which later became known as “dry-walled”. For the standard system of elevators serving the skyscraper, it would be necessary to use almost half of the entire floor space of the lower tier in order to place elevator shafts in it, which was not economically viable. Therefore, the specialists of Otis Elevators developed a special system called “fast” and provides for the transfer of passengers on the 44th and 78th floors of buildings. Such a system of elevators allowed to reduce the number of elevator shafts in half, compared with the traditional system. As a result, the Twins Tower complex operated 239 elevators, as well as 71 escalators. Each elevator was designed for a carrying capacity of 4535 kilograms, that is, it could lift 55 people at a time. The speed of the elevators was 8.5 meters per second. By the way, engineers also used this system of "transplants" when designing other skyscrapers, which were born much later than Gemini.

During the construction of the facility more than once financial difficulties arose, but, despite this, the construction not only did not stop, but also continued rapidly. In the years 1965-1970, the authorities in New York could not fully finance the construction, so loan bonds were issued. In 1970, a major economic crisis erupted, as a result of which payments on bonds by the authorities were discontinued. First, the administration decided to freeze the construction for several years. But then this seditious idea was abandoned, because the prestige of the United States could greatly suffer from these measures. Then economists developed another way of financing and money was found. Taxes for entrepreneurs were increased, contracts for the lease of office space in the WTC skyscrapers (prepaid), etc. were concluded.

The construction of the North Tower was completed in 1971, and two years later the South Tower was also commissioned. The official opening date for the World Trade Center in New York is April 4, 1973.

Characteristics of the WTC Towers

As a result, the twin towers became the highest skyscrapers in the United States. Each "giant brother" had 110 floors. The height of the 1st WTC building was 526.3 meters along with the antenna. The last floor in the South Tower rose 411 meters from the ground, and in the North - 413! The depth of the foundation was 23 meters below the ground. The length of the power cables exceeded 5,000 kilometers, and the total power of the electric network amounted to about 80,000 kW. Thus, the builders really managed to realize the "Project of the Century", which became one of the symbols of the USA, the pride of the American people.

In the last years of the Complex's existence, about 50,000 people came to work at the WTC every day, and another 200,000 people visited the World Trade Center a week as tourists.

  An observatory was organized in the South Tower on the 107th floor. A magnificent view of the city opened from the observation platform. In the North Tower at a level between 106 and 107 floors there was a chic restaurant “Windows to the World”, which was opened in 1976 and was the most “high-altitude” food center in the world.

At that time, no one could have thought that these towers would once fall. Indeed, the frame of the building, according to engineers, could withstand the blow of tremendous power, for example, when rammed by plane. The towers were all the more unafraid of the strongest gusts of wind that raged at an altitude of 400 meters. The design of the skyscrapers was characterized by high strength and stability, thanks to the facades made in the form of steel frames and aluminum modular sections mounted in them. These elements had dimensions of 10x3.5 meters. All technical tricks turned out to be in vain, since not the destructive force of the collision, but the high temperature played a decisive role in the fall of the aircraft. As a result of the explosion of fuel tanks containing more than 5,000 liters of gasoline, there was an instant heating of steel to 1000 degrees Celsius! This provoked the collapse.

  reference

Currently, construction of new three skyscrapers is underway on the site of the twin towers, under the working names Tower No. 2, No. 3, and No. 4 and a tower 541 meters high, which received the symbolic name Freedom Tower. All new buildings will be very different from the first towers that fell during the attack. The ceremony of starting the construction of the new World Trade Center was held in July 2004, and the construction itself began on April 27, 2006. The development of the site is carried out by Larry Silverstein, a real estate entrepreneur. According to the plan, the construction of the Freedom Tower should be completed before 2013. In addition to this tower, the new World Trade Center in New York will also include a residential skyscraper, three high-rise office buildings, a museum and a memorial to the victims of the September 11, 2001 tragedy, as well as a concert and exhibition center. Many Americans have christened the 540-meter high skyscraper the Tower of Fear, as during its construction, innovative technologies will be used that prevent destruction during a terrorist attack of any force. In particular, it is planned to clothe the first 52 meters of the building in a concrete frame, and use prismatic glass for exterior decoration, the only way to avoid the notorious visual effect of a “stone bag”.

The construction of this complex was a symbol of the postwar prosperity of the United States of America. Its destruction 11 years ago became a new reference point, dividing the history of the planet into regular “before” and “after”. Behind these events of gargantuan proportions, the fact that the buildings built in the early 1970s were an outstanding engineering structure of their time is practically not noticeable. The blogger Darriuss tells about the World Trade Center, which lasted only 30 years, but managed to become one of the architectural icons of New York.

The United States emerged from World War II as a superpower. Its largest city, New York, having become the capital of world diplomacy with the United Nations headquarters here in 1945, was seriously preparing to turn into the most influential center of international trade. However, the initial plans for the construction of the necessary infrastructure for this, which included the construction of a complex of 21 buildings in the early 1950s with a total value of $ 150 million, were frozen in 1949.

Again to the so-called project The World Trade Center returned at the end of the next decade, tying it to redevelopment of Lower Manhattan, initiated by billionaire David Rockefeller. He attracted the largest US architectural firm to create the WTC concept. -   Skidmore, Owings and Merrill from Chicago, which presented in 1960 a preliminary design for the new complex in the eastern part of the island, along the East River. World Trade Center in SOM view consisted of 50 - 70-story high-rise building in the "international style", reminiscent of the UN headquarters (office premises and a hotel were supposed to be located here), and the long (275 meters long) exhibition center adjoining it. Variant of 1960.

A year later, an option was proposed with several high-rise buildings.

In 1961, the developer of the project became the so-called Port Authority, the New York Port Authority, an organization responsible not only for the port facilities of the metropolis, but also owned its entire coastal infrastructure (land, tunnels, roads), and not only the city of New York itself but also the state of New Jersey in its area. After consultations between the Port Authority and the US authorities, a conceptual decision is made to move the WTC construction from the shores of the East River to the opposite, western side of Manhattan. The original World Trade Center site is highlighted in orange, red - new, where the project was eventually implemented.

This site (already on the banks of the Hudson River) was much more beneficial for the state of New Jersey, located on the opposite side of the river. In accordance with the mutual agreements, the New York Port Authority bought from New Jersey the unprofitable high-speed underground railway Hudson and Manhattan Railroad, which connects the state with Manhattan. After -   demolished its main Manhattan terminal (Hudson Terminal), without affecting the actual tunnels of the road, and started the construction of the WTC in its vicinity. In this 1919 photo showing the skyline of a city still in Art Deco style, Hudson Terminal -   these are two dark buildings to the left of the center of the picture. The WTC is located on the site of low-rise buildings in the lower left corner.

The demolition of these quarters caused a considerable scandal at the beginning of the construction of the Center. Its skyscrapers were designed on the site of Radio Row (Radio Series), a Manhattan area where hundreds of small shops, offices and warehouses selling radio and other electrical equipment were located. So Radio Row looked in the 1930s, some buildings here date back even to the 1850s.

So this area looked like a bird's eye view. The white line marks the site that the WTC complex eventually occupied.

Many shop owners at Radio Row and about a hundred people who owned apartments there, as often happens, categorically refused to move anywhere, even for compensation. Pickets, demonstrations and lawsuits, however, were not particularly successful. This project was too important for municipal authorities; the amount of mastered investments was too large.

Resettlement of Radio Row began in 1965 and by 1967 basically ended.

Five years later, modern skyscrapers will grow here.

New York skyline from the opposite, New Jersey, coast of the Hudson. In the center -   low-rise Radio Row, behind it -   Hudson Terminal. Please note that the train station looks like the symbolic predecessor of the WTC. Also two towers (1909, architect James Hollis Wells, Clinton and Russell bureau), at one time high-rise (22 floors), almost twins, served as a business center located above the railway terminal hidden underground.

On September 20, 1962, having finally decided on the site and got involved in the battle for the resettlement of the site, the Port Authority chose the main architect of the project. He became an American of Japanese descent Minoru Yamasaki. He lived in the vicinity of Detroit, pc. Michigan, and therefore, to provide him with technical assistance, a local New York workshop Emery Roth & Sons was appointed. The customer posed the following task for Yamasaki: to place 930,000 square meters on a 16-acre (65,000 sq. M) site. m of office space. The architect went through several dozen conceptual options: a single skyscraper, a smaller set of “skyscrapers”, but in the end he settled on the option of building two 110-story twin towers surrounded by several relatively low-rise buildings. 1964 sketch

In January 1964, a mock project was presented to the city and the world.

So, the plan of the World Trade Center. Its main elements were two identical “skyscrapers”, the so-called North and South towers (1 WTC and 2 WTC on the plan, respectively). The perimeter of the building spot was completed by 4 buildings with complex configurations, which received numbers 3-6 and were built in 1975 - 1981 years. A large area was created in the center of the site (“plaza” in American terminology), which served for the recreation and distribution of pedestrian flows into the buildings of the complex. All six buildings formed one giant “super quarter” (superblock), which took the place of a dozen previously existing here. Finally, in 1987, the WTC included a high-rise business center (7 WTC), which formally went beyond the original site.

The twin towers were designed square in plan with a side length of 63 meters. The fundamental innovation of Yamasaki was the proposal to build them with a supporting outer frame that forms a rigid "pipe", which would be complemented by an inner core standing on the rocky base of Manhattan. Such a design, instead of the previously used mass scheme with columns carrying loads distributed over the entire internal area of \u200b\u200bthe building, made it possible to obtain more office space. In addition, the latter were suitable for subsequent free planning at the request of tenants.

Typical floor plan of a skyscraper. The external frame of the building is formed by perimeter metal columns (59 pieces on each side of the building, the length of the side of the column - 36 cm, marked on the plan in small squares). The corners of the square perimeter are beveled. In the center is a rectangular (27 × 41 m) core, the base of which is another 47 steel columns, standing directly on the rocky base of Manhattan Island. The engineering infrastructure is also concentrated in the core: technical mines, elevators, stairs, utility rooms and auxiliary rooms. Office space surrounds the core and is completely free of supporting columns.

The interfloor ceilings connecting the perimeter columns, taking part of the weight load and redistributing the wind load gave additional stability to the building frame. Structurally, each of these ceilings consisted of a grid of steel trusses (main and connecting transverse), covered with sheets of corrugated metal and poured on top with a thin layer of concrete.

Interfloor ceilings and the supporting external frame of skyscrapers close-up.

In addition to the structural design of the building, Yamasaki also used a number of other advanced solutions at that time. For example, he faced the following problem inherent in all high-rise buildings. The higher the skyscraper, the more elevators are required to serve its inhabitants. With an increase in the number of elevators, the useful area of \u200b\u200bthe tower decreases in direct proportion. The architect found an elegant way out of this situation. He divided the entire office volume of the WTC skyscrapers into 3 equal parts. The floors between them (the 44th and 78th) were given under the so-called "sky lobby" (sky lobby). The role of the third lobby was performed by the reception on the ground floor of the tower, called Concourse. The idea was like that. All elevators in the core of the skyscraper are divided into huge “express elevators” that can accommodate several dozen people, but moving only between interchange “heavenly vestibules”, and several clusters of “local” elevators, each of which served its own set of floors for a particular tower segment. Such a scheme made it possible to evenly provide each floor of the high-rise building with elevators, while without uncontrollably inflating their number (we stopped at the figure of 99 elevators per tower). The traditional scheme would allow only 62% of the area of \u200b\u200beach floor to be used as an office, the interchange lobby increased this figure to 75%. There were direct "express lifts" moving exclusively between the 1st and 107th (last inhabited) floors of the towers, where the restaurant and observation deck were located.

The floors of the Sky lobby were interlocked with the technical floors where the tower equipment was located. On the facade of the skyscrapers, these auxiliary levels are well marked.

The corporate identity of Yamasaki, who loved tall, narrow, almost gothic windows in the profile (as they say, not least because of his own fear of heights), fit perfectly into the design of skyscrapers. A frequent grid of supporting external columns made it possible to make windows only 45 cm wide, which is why from a distance the towers always looked like a solid steel monolith.

Upon closer inspection, the monolith turned out to be not at all continuous, and also not even steel. For better corrosion resistance, the metal frame of the building is lined with aluminum alloy panels.

In March 1965, Port Authority began buying real estate at the WTC promising site. A year later, in parallel with the resettlement of the site, the demolition of its old buildings begins, ending in 1967.

At the excavation stage, architects, engineers and builders face a serious problem. The fact is that the purchased site, formally being Manhattan, was actually a very conditional part of the island. Over the centuries of its development, the original coastline has changed significantly. Faced with a lack of territory for construction, local residents were actively engaged in the reclamation of new areas. In this diagram, the original Manhattan coastline is marked with blue dots, its alluvial territories are highlighted in gray, and a red circle -   WTC location.

The future World Trade Center was located just on the alluvial site, and for the construction of buildings it was necessary to get to the rocky base, hidden 20 meters of alluvial soil.

Already at the end of 1966, to solve the problem, the formation of the so-called “bathtub” began. The WTC site is fenced using the “wall in soil” technology: roughly speaking, a rather narrow trench is dug around its perimeter, which is subsequently poured with monolithic concrete (the whole process took 14 months). After removal of alluvial soil, a huge foundation pit is formed, surrounded by a concrete wall that prevents the entry of groundwater and water from the Hudson River. The foundation pit, which was called the "bath", is the required rock. Photograph of July 1968.

Left -   "Wall in the ground." WTC was one of the first examples of the large-scale use of this technology. The WTC frame is visible on the right.

In the process of forming a “bath”, a million cubic meters of alluvial soil was extracted from it, which had to be disposed of. The architects again acted extremely elegantly: 917,000 cubic meters of excess land moved only a few tens of meters to the west and formed a new alluvial site, which the developers of the project subsequently were also able to use for commercial construction. In this image, the alluvial site in the Hudson is in the foreground. To the left is the former coastline with piers.

The increase in Manhattan's area continues. In the right corner (with the stadium) Battery Park is visible. In honor of him, the area, located on the plains conquered by the river (left), was called Battery Park City.

In this wonderful picture, which demonstrates that New York is also a city of contrasts, the twin towers from the Hudson and the new alluvium are not obscured by anything.

Since 1980, the development of the alluvium began. Ultimately, dozens of residential, administrative and public buildings are located here, including the so-called World Financial Center, which constitutes a single cluster with the WTC. The towers of the VFC and eventually blocked the WTC from the Hudson.

As already mentioned, the World Trade Center was built near the Hudson and Manhattan Railroad subway station. One of the features of the development of the territory was the presence on it of two tunnels of the railway. Amazingly, the construction of skyscrapers did not interfere with her work. During the formation of the bath, the tunnels were excavated and then built into the underground levels of the complex, where a new station was later organized, instead of the demolished Hudson Terminal station. Pay attention to the upper right part of the image - this is a fragment of the tunnel.

In addition to the railway station, a huge shopping mall and parking for 2,000 cars were built in the "bath". The tunnel in the foreground of a 1969 photograph.

And in this picture you can see that the frame of the twin towers was going right around the tunnels.

The lower six floors of the skyscrapers formed huge vestibules. Here the supporting columns were more powerful, but were less frequent, which provided better natural lighting for the lobby and reception area. At the level of the sixth floor, the columns were disordered, forming peculiar tridents, Minor Yamasaki's signature artistic device.

The supporting columns of the external perimeter were made of steel at third-party enterprises and delivered to the construction site in already partially assembled blocks, which allowed to significantly intensify the construction process. Each such element weighed 22 tons. On average, one floor of the tower was built in 5 days, and the assembly of the entire 110-story high-rise took only a year and a half.

For construction, special Kangaroo self-expanding cranes purchased in Australia were used.

The structural diagram of the towers is clearly visible: the inner rectangular core and the external supporting frame.

Particularly spectacular “twins” looked at sunset, when the sun shone through them through.

The north tower was built from August 1968 to December 1970, the south - from January 1969 to July 1971. The entire complex cost the developer $ 900 million in 1971 prices, although it was initially estimated at $ 350 million. The total weight of the steel spent on the construction of the complex was about 200,000 tons.

In color photographs, the characteristic rusty color of the metal structure of the frame is clearly visible. Subsequently, it was treated with special anti-corrosion and fire-fighting compounds, but instead of painting it was lined with aluminum panels.

The process of building (above), processing (behind yellow screens) and cladding (below) of skyscrapers went in parallel.

  The construction of the North Tower was completed in 1971, and two years later the South Tower was also commissioned. The official opening date for the World Trade Center in New York is April 4, 1973.
  WTC Towers Feature:
As a result, the twin towers became the highest skyscrapers in the United States. Each “giant brother” had 110 floors. The height of the 1st WTC building was 526.3 meters along with the antenna. The last floor in the South Tower rose 411 meters from the ground, and in the North - 413! The depth of the foundation was 23 meters below the ground. The length of the power cables exceeded 5,000 kilometers, and the total power of the electric network amounted to about 80,000 kW. Thus, the builders really managed to realize the "Project of the Century", which became one of the symbols of the USA, the pride of the American people. In the last years of the Complex's existence, about 50,000 people came to work at the WTC every day, and another 200,000 people visited the World Trade Center a week as tourists. An observatory was organized in the South Tower on the 107th floor. A magnificent view of the city opened from the observation platform. In the North Tower at a level between 106 and 107 floors there was a chic restaurant “Windows to the World”, which was opened in 1976 and was the most “high-altitude” food center in the world. At that time, no one could have thought that these towers would once fall. Indeed, the frame of the building, according to engineers, could withstand the blow of tremendous power, for example, when rammed by plane. The towers were all the more unafraid of the strongest gusts of wind that raged at an altitude of 400 meters. The design of the skyscrapers was characterized by high strength and stability, thanks to the facades made in the form of steel frames and aluminum modular sections mounted in them. These elements had dimensions of 10x3.5 meters. All technical tricks turned out to be in vain, since not the destructive force of the collision, but the high temperature played a decisive role in the fall of the aircraft. As a result of the explosion of fuel tanks containing more than 5,000 liters of gasoline, there was an instant heating of steel to 1000 degrees Celsius! This provoked the collapse.

  The destruction of the World Trade Center.

Evidence of explosives in the Twin Towers.

Millions of people around the world watched the events around the WTC live on CNN on September 11, 2001 and could hardly believe their eyes. They saw huge puffs of smoke over Manhattan and saw the towers collapse ... in a strange way. They did not fall apart; they “FOUND”, thus, as many saw during the CONTROLLED DEMO: the building does not collapse chaotically, scattering debris over a wide area; rather, it collapses on itself. That is how the towers of the WTC collapsed.
That the destruction of the towers was controlled was immediately noticed by some astute observers:
  Well, is it just me, or did someone else understand that the WTC was not destroyed by aircraft attacks? For me personally, this is the most frightening moment of this morning. ...
  If you look at the timing, you will see that everything happened as follows:
  - The plane crashes into the 1st tower, making a break at the very top. Further quite expected things happen:
  - The tower remains standing. Reinforced concrete building * extremely * solid. Terrorists have already detonated a large bomb * inside * the same building without much damage. ...

The second plane crashes into the second tower, lower and at higher speed. He punches a larger hole in it, debris pours into the streets, but the building nonetheless stands and looks quite solid.
  - The second building starts to burn, also up from the scene of the collision.
  - About half an hour later, the fire in the first building * goes out *. It is still smoldering and black smoke is coming, but there is no flame. ...
  - The fire in the second building went out.
  - The second building suddenly crumbles into dust, as if a smooth wave ran from the top of the building (above the burning place) down through all floors at the same speed. The wreckage mostly falls inward. Separate whole pieces do not fall off the building and do not collapse on the surrounding houses. ... The destruction began from the top (above the point of collision). It happens evenly. All structural elements are destroyed sequentially, so that there is no supporting skeleton. Destruction is uniform, symmetrical and absolute.
  To summarize: it all looks like demolition - because that is it.
  - The first tower collapses as a result of a similar "wave".
  There is no doubt that the planes crashing into the towers caused serious damage. But take a look at the photographs - these buildings simply * flattened *. Demolition of the building does not require a lot of explosives, but it needs to be placed in the right places (in direct contact with the structural elements) and undermined in a uniform, synchronized sequence. ...
  This message appeared on the Internet on September 11, a few hours after the destruction of the Twin Towers. From the very beginning, some people were not deceived.

Initially, the theory with explosives had a problem: there were no reports in any media that anyone heard the explosions immediately before the collapse of the WTC. But over the past year, such messages have appeared, there is even a free video recording demonstrating that there were actually explosions inside the Twin Towers before they collapsed.
  Viewers watching the terrible events of September 11 saw explosions before the collapse of the towers. The television images show what looks like a massive explosion that occurred close to ground, close to the 47-story Salomon Brothers building, known as the WTC-7, before the collapse of the first tower.
  ... One witness, whose office is near the World Trade Center, told AFP that he was standing in a crowd on Church Street, about two and a half blocks from the South Tower, when he saw a “series of short flashes coming from inside the building between 10 and 15 floors. " He saw about 6 of these short flashes, followed by a “bang” before the tower collapsed. Each tower had six supporting columns.
  One of the first firefighters in the second attacked tower, Louie Cacchioli, 51, told People Weekly on September 24th: “I lifted firefighters in the elevator to the 24th floor to evacuate employees. During the last climb, a bomb exploded. We believe that in bombs were mounted on the building. "
  Kim White, 32, an employee from the 80th floor, also said she heard an explosion. “Suddenly the whole building shuddered, then it started to swing. We did not know what was going on,” she told People. "We gathered all the people from the floor to the flights of stairs ... at that time we all thought it was a fire ... We went down to the 74th floor ... then there was another explosion."
  (Many testimonies insist on the presence of bombs during the collapse of the WTC).
  The Danish site offers a 4-hour video footage containing evidence of what happened on September 11th and what was silenced or ignored by the mainstream media:
Video clips of the falling Towers were often edited in such a way that did not allow viewers to get a “Full picture” of the entire collapse of the towers. ... During the 1000 hours of my video investigation, I found very few such "full-length images taken from a long distance" that would show the entire tower (top to bottom). Most of the video clips about September 11th that we saw (and over the coming weeks) are edited versions ... [which] do not show at all the numerous “clouds” from the EXPLODING bombs “exploding from the windows” of the WTC façade well below the collision site. ... Someone in the "editorial" did not want to show us the "Full Picture"!
  But some of the most important BOMB video testimonials remain! In my video I will show you 5 significant “DUST CLUBS” from destructive bombs exploding INSIDE the WTC Towers. These "bomb clouds" were located at about 20 and 40 levels BELOW the "collision level" of the falling towers. ... They give full proof of the existence of Destruction Bombs detonated MUCH BELOW "the level of the point of collision."
  ("Bombs inside the World Trade Center").
________________________________________
  The WebFairy 911 Memorial has some very interesting video material. Of particular interest is the clear evidence of the explosions that occurred during the fall of the North Tower.
  In the left picture is a shot of controlled demolition: pay attention to what “WebFairy” calls “firecrackers for demolition,” clouds of debris and dust that are thrown horizontally when an explosion of charges placed at several levels in the building to be demolished.
  Now look at the right shot: this is a shot of the collapse of the North Tower. Two horizontal bursts from explosions are clearly visible before the debris reaches the bottom of the frame.
________________________________________

But not only the Twin Towers were intentionally destroyed, but also the building known as the WTC 7.
  "Not quoted by the monopolized press, some firefighters who survived Black Tuesday insist that there were explosions in the buildings, in part of the twin towers of the World Trade Center, separately and away from the impact of aircraft crashing into the buildings. ... Was the explosives inside the buildings blown up remotely to demolish towers, as they do with old buildings? And there are serious reasons to believe that the explosives inside caused a mysterious collapse, already on Black Tuesday evening, of building number 7 of the World Trade Center complex. "
  (Sherman H. Skolnick: "The Overthrow of the American Republic," Part 14).
________________________________________

The Twin Towers collapsed in a very strange way, there was practically nothing left but metal fragments of the outer wall and a huge amount of fine ash and dust, without central steel columns of the lower sixty floors, standing or falling. It is very strange. Take a look at all this dust (click on the image to enlarge it, and also see the next two photos of dust clouds). As if some kind of high-energy destructive beam was focused on the towers, spraying each concrete block into the smallest particles of ash and dust.
________________________________________

But, although some types of "dark" technology could be used to destroy the Twin Towers, we do not need to prove this, since the fall could well be explained by controlled demolition using explosives. In fact (as Christopher Bollyn was the first to indicate in his Open Letter), evidence of strong explosions was recorded by seismographs located 34 km from the World Trade Center:

  “Sharp peak of short duration” - this is how an underground nuclear explosion looks like on a seismograph.
  The seismograph that recorded this data worked at the Columbia University’s Lamont-Doherty Earth Observatory. The U.S. Geophysical Union published a message in the Eos issue of November 20th, but the authors misinterpreted the data. They speculated and reported that the two biggest signals were caused by the fall of the Twin Towers. But:
  "During the collapse, most of the energy of the falling pieces was absorbed by the towers and surrounding structures, converting them to debris and dust, or causing other damage - but not causing significant earth shake."
  (Dr. Arthur Lerner-Lam, director of Columbia University’s Center for Hazards and Risk Research, as cited in Earth Institute News).
  Thus, if most of the energy of the falling debris was dissipated and was not the reason for the appearance of the main peaks in the seismic record, then what was it? Perhaps the strong explosions at the lowest levels (minus the 7th level) of the Twin Towers foundation, near the bearing steel columns, where they rested on the Manhattan rock? Maybe even small NUCLEAR explosions?
This, together with numerous small explosions at every tenth or so level of the supporting steel columns, may explain the observation, which the official version does not explain: why did not the bottom of the massive steel supporting columns stand after the collapse? If the official version is true that the destruction was the result of collisions and fires, which occurred only on the upper floors, and that the floors then “settled” on each other, it would be expected that the steel columns in the core, say, 20 or 30 lower floors should have remained standing, which did not happen. But this becomes clear if the bases of the steel columns were destroyed by explosions at rock level. With the base destroyed and bearing steel columns interrupted by explosions at different levels of the Twin Towers, the upper floors lost their support and collapsed to ground level in about ten seconds.
  Further evidence of the presence of explosives is provided by a video of how the South Tower collapsed: approximately 30 upper floors tilted at the beginning of the collapse. If the floors "sat down" on each other, as the official version claims, then these upper floors should have fallen directly down. But if the explosions somewhere near the level of the collision killed the steel supporting columns in the center, then it is clear why the upper floors tilted (possibly towards the damaged corner, where the plane crashed).
  Explosive devices could be enclosed in a heat-resistant shell so that they would not explode from a fire. If synchronization was important, then they could be detonated remotely (by radio or microwave) at the right time. Even if the fire had disabled the bombs at the collision level of the aircraft, he could not have damaged the bombs below the fire level. You don’t need wires, processors or clockwork, you only need a method that undermines each device with a unique signal. Even a synchronous sequence might not be needed - the simultaneous explosion of all devices at ground level could be sufficient to achieve the desired result.
The time t required for the object to fall from a height h (in vacuum) is calculated by the formula t \u003d sqrt (2h / g), where g is the acceleration of gravity. Thus, an object falling from the top of one of the towers (take h \u003d 1306 feet (398 meters) and g \u003d 32.174 feet / second 2 (9.81 meter / second 2)), it will take 9.01 seconds before it falls to the ground, if we neglect the air resistance and for a few seconds longer, if we take into account the air resistance. The Twin Towers collapsed in 10 - 15 seconds, which is close to free fall. Immediately after the start of the destruction, the upper floors were to smash into pieces the steel lintels in all 85, or so, floors of the lower levels. Even if it took a second to the floor, the collapse would take more than a minute. But the material of the upper floors collapsed on the lower floors at a speed of at least six floors per second. This is possible only if all the structural elements of the lower 85 floors were completely destroyed before the collapse. Since the lower floors were not damaged in a collision with an airplane and a fire, the removal of structural support on these floors had to happen for another reason - and the most obvious possibility is explosives. T.O. the collapse rate (not particularly exceeding the free fall rate) is strong evidence that the Twin Towers were destroyed in a controlled demolition using explosives (or other destructive technology) at all levels.
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For a week after the collapse of the Twin Towers, there were areas under the surface that remained extremely hot.
  "The AVIRIS data obtained on September 16, 2001, found a number of thermally hot spots at the collapse of the WTC towers. An analysis of the data found temperatures above 800oF (430oC) at these places (some above 1300oF (700oC)).
  ("American Geological Observation Report").
  What was the source of this heat? Maybe residual effects from underground nuclear explosions?

A way to prove that the supporting steel columns of the Twin Towers were interrupted by explosives would be to study their wreckage for what metallurgists call "twinning." But the WTC ruins were cleared as quickly as possible, and no investigative investigation of the wreckage was allowed by the FBI or another government agency. Almost all 300,000 tons of steel from the Twin Towers were sold to New York scrap merchants and exported to places like China and Korea as fast as ships could be loaded, thus destroying evidence. See “The Mountain of Debris Begins to Decline” for Controlled Demolition Inc. (the world leader in demolition of high-rise buildings) apparently took good care to remove the debris and get rid of it as quickly as possible, and was able to provide a detailed plan for these events 11 days after the destruction of the Twin Towers, which suggests that this company has detailed information about the Towers- Gemini and the entire WTC complex before September 11th.
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It can be argued that hundreds of security guards and hundreds of surveillance cameras (possibly) worked in the WTC. With such a security service, it would be possible to plant a couple of bombs, but to plant many of them (especially powerful enough to destroy the bases of the supporting steel columns) seems impossible. However, the World Trade Center changed ownership 11 weeks before the attack. The new owner was Larry Silverstein. The destruction of the WTC and George Bush’s declaration of the “War against Terrorism” proved (and one could predict) extremely beneficial for Israel in its brutal suppression of the Palestinian people, in its efforts to destroy the Palestinian leadership called “terrorist”, and in its attempts to dominate all Arab neighbors . The new owners of the WTC could well be persuaded to cooperate in terms of such an obvious benefit for Israel. But if 11 weeks is considered insufficient for laying explosives, then what about a few years?

Terrorist attack or controlled bombing?
  According to science, "fire (fire) could not lead to the destruction of the steel structures of the building." Supporters of the official (government) version of the tragic events ignore this fact. Moreover, according to a report signed by the Directorate of the National Institute of Standards and Technology (2005), the steel structures of buildings collapsed allegedly as a result of fires. At the same time, no such fact is known to science.
Interestingly, the towers were designed taking into account a possible air attack and were created with design durability that allows them to withstand a collision with such a colossus as the Boeing 767.
  "They were designed to withstand all kinds of influences, including tornadoes, bombing or collisions with huge airliners," says Hyman Brown, project manager for the construction of twin towers (2001).
  The theory of the destruction of a building by fire and the melting of load-bearing steel structures is also absurd. According to experts, the destruction of skyscrapers resembles a “controlled blasting,” when a certain amount of explosives is placed in the supporting structures and fires in the right sequence.
  During a controlled blast, the destruction of the building occurs suddenly - at first there is nothing, but in the next instant the building breaks up. The steel structure at high temperature cannot suddenly break. This happens gradually - horizontal beams begin to bend, and then the vertical steel columns are deformed.
  But the video recording of the destruction of the towers did not record such processes even on the floors located above the hole left by the plane. In addition, the art of controlled demolition of a high-rise building is to ensure that the blown up skyscraper does not scatter in all directions, but sags so that the wreckage remains exclusively at the construction site. This is what happened with the towers.
  According to Marc Loisier, president of the largest controlled building demolition company, such an explosion "must be fully planned, and the explosives must be placed in a certain order." All 110 floors of the twin towers collapsed very neatly. With an unplanned explosion, construction debris would cover the entire area, but this did not happen.
  With a controlled blast, the remains of the building descend to the surface with a free fall speed, which does not happen in the event of an accident. To do this, the demolition team first lay explosives under the supporting systems of the lower floors, so the upper ones go down, almost without resistance.
According to the commission’s report, the south tower collapsed in 10 seconds, which corresponds to a controlled demolition. Moreover, this technique allows you to "cut" bearing steel structures into parts of a certain length, which was recorded in New York. A huge cloud of dust formed on the site of the towers after the explosion also serves as indirect evidence of a controlled explosion. This conclusion was made by Colonel of the US Engineering Forces John O. “Daoud." It seemed that the air at the site of the WTC explosion was saturated with cement dust. "
  Another proof of a planned explosion is a huge amount of molten steel at the site of the collapse of the towers. So, Peter Tully, the head of the Tully Construction construction company, and Marc Loisier reported on the “molten steel lakes” found on the site of the collapsed buildings in the underground elevator shafts. Meanwhile, the collision of the aircraft with the building and the subsequent ignition of aviation fuel could not lead to the formation of temperatures at which steel structures begin to melt. The mystery of the explosion of the twin towers, according to scientists, is still unsolved. But what about the government? It is inactive, refusing to divulge information contrary to official theory.
  Shortly after the events of September 11, over 500 New York City fire and ambulance officers gave oral evidence, one way or another, indicating some inconsistencies noted during the liquidation of the consequences of the attack. New York City Hall has done everything to not publicize or refute these facts.
  Only in August 2005 did The New York Times and a group of relatives of those killed in a lengthy trial and a series of appeals manage to force the city hall to publish the mentioned evidence of direct witnesses to the death of the WTC.
  The words of witnesses refute government theories, arguing that the events of September 11 are a well-planned act of intimidation.

Unfortunately, American officials do not want to conduct an independent investigation, establish the truth and punish those responsible. Why is this happening? To whom and why is it profitable? These questions remain unanswered, but the public is not satisfied with the position of the Bush administration, and the S9 / 11T group does not intend to cease its activities. Soon, new details await us, revealing the essence of these tragic events and the hypocrisy of officials. If the allegations of American scientists turn out to be true, a “controlled disruption” could well lead to an uncontrolled reaction of society - not only American, but also worldwide. And then the authors of the largest hoax in the history of mankind may not be greeted.

Reference.
  Currently, construction of new three skyscrapers is underway on the site of the twin towers, under the working names Tower No. 2, No. 3 and No. 4 and a tower 541 meters high, which received the symbolic name “Freedom Tower”. All new buildings will be very different from the first towers that fell during the attack. The ceremony of starting the construction of the new World Trade Center was held in July 2004, and the construction itself began on April 27, 2006. The development of the site is carried out by Larry Silverstein, a real estate entrepreneur. According to the plan, the construction of the Freedom Tower should be completed before 2013. In addition to this tower, the new World Trade Center in New York will also include a residential skyscraper, three high-rise office buildings, a museum and a memorial to the victims of the September 11, 2001 tragedy, as well as a concert and exhibition center. Many Americans have christened the 540-meter high skyscraper the “Tower of Fear,” because during its construction, innovative technologies will be used that prevent destruction during a terrorist attack of any force. In particular, it is planned to clothe the first 52 meters of the building in a concrete frame, and use prismatic glass for exterior decoration, the only way to avoid the notorious visual effect of a “stone bag”.