Since 9/11 Hundreds of Skyscrapers Have Been Built, But How Safe Are They?

When al-Qaeda carried out the attack on the World Trade Center in New York hundreds of people found themselves trapped on the upper floors of the Twin Towers. They were eventually replaced by a skyscraper - known as the Freedom Tower - which is even taller.

If a 9/11-style attack were to take place again in New York, Chicago, London or Dubai how would you rescue the people trapped at the top of the world’s tallest skyscrapers?

Considering improvements to international aviation security it is unlikely a large commercial airliner could be hijacked and flown into a building like it was on 9/11.

But that does not mean that a fire could not break out on halfway up one of the world’s skyscrapers and spread upwards, trapping hundreds or even thousands of workers or residents.

Despite the horror of 9/11 architects and property developers did not stop building skyscrapers. Quite the opposite.

The Council on Tall Buildings and Urban Habitat published a survey recently which found that 86 of the world’s 100 tallest buildings were constrcuted since 2001.

The CTBUH said: “After witnessing the collapse of the World Trade Center towers due to terrorist attacks, many people, including some in the building industry, believed that we would no longer be comfortable living, working, and socialising in such iconic buildings, given their potential as high-profile targets. Yet 20 years later, the data study below indicates the exact opposite, with more than five times as many tall buildings built since 9/11 than existed before.”

In the immediate aftermath of 9/11 there were a number of articles published which suggested skyscrapers could be built with giant escape chutes.

While no such chutes were ever constructed, several inventors have come up with escape devices which work on the same principle.

But they have a height limit. Most cannot be used above 147 feet, or 13 storeys.

The Freedom Tower is 1,368 feet tall - 104 storeys - not including its spire, while the Burj Khalifa in Dubai has 160 floors.

Another possible means of escape from a towering inferno would be by helicopter.

But neither the Burj Khalifa or the Freedom Tower have a helipad at the top of the building and even if they did, it might not help.

In September 2001 helicopters were sent up to see if they could rescue people from the Twin Towers but the smoke was so thick that they were unable to land safely on either building’s helipads.

Fire damaged cladding is seen on the lower floors of the fire-gutted Grenfell Tower in London, Friday, June 16, 2017, after a fire engulfed the 24-story building Wednesday morning

© AP Photo / Matt Dunham

When the Grenfell Tower fire broke out in London in June 2017, killing 72 people, the fire brigade discovered their ladders could not rescue people beyond the ninth floor.

So, as in 9/11, the only way for firefighters to mount a rescue is by climbing up the stairwell inside a building and physically bringing people out.

The first hijacked plane on 11 September 2001 struck between the 93rd and 99th floor of the North Tower and 15 minutes later Flight 175 hit the South Tower between the 77th and 85th storeys.

FILE PHOTO: 20th anniversary of the September 11 attacks

© REUTERS / STRINGER / FILE PHOTO: 20th anniversary of the September 11 attacks

Hundreds of New York firefighters were deployed to try and rescue people trapped by the ensuing blaze.

When the South Tower and then the North Tower came down they claimed the lives of 343 firefighters as well as 23 police officers and 37 Port Authority employees.

But despite the heroism of the firefighters there is no way they could have saved those who were trapped on the upper floors of either tower.

Dozens of them, trapped by fire and smoke, took the desperate decision to jump, knowing certain death awaited them below.

Ironically the architect who designed the Twin Towers, Minoru Yamasaki, was scared of heights and deliberately designed the buildings with narrow windows in order to make office workers feel secure.

Yamasaki’s towers were finally opened to the public in 1973.

The following year the top-grossing film of the year was Towering Inferno, starring Steve McQueen, Paul Newman, William Holden and Faye Dunaway.

The film tells the fictional story of a fire on the upper floors of a new 138 storey skyscraper, the Glass Tower, in San Francisco.

At the end of the film fire chief Michael O’Halloran (Steve McQueen) tells architect Doug Roberts (Paul Newman): “We were lucky tonight. The body count is less than 200. One of these days it’ll kill 10,000 in one of these firetraps and I’ll keep bringing out bodies until somebody asks us how to build ‘em.”

Paul Newman’s character responds by accepting the offer.

The Freedom Tower has been built with a welter of new safety measures which were drawn up following consultation with the New York Fire Department.

The National Institute for Standards and Technology found the design of the original Twin Towers meant they were not strong enough to withstand the impact of commercial airliners and the fireballs that followed.

Twenty years after September 11th 2001 the Freedom Tower continues to rise from the ashes. We will #NeverForget pic.twitter.com/BRh8Z66064

— NYPDCounterterrorism (@NYPDCT) September 8, 2021

The architect David Childs, of Chicago firm Skidmore, Owings and Merrill (SOM), says the concrete they have used in the Freedom Tower is strong enough to resist fire or even a plane crash.

The main feature of the Freedom Tower is a specially strengthened central core which contains stairwells, liftshafts, water pipes and communication cables.

The architects say that in the event of a 9/11-style disaster it would allow people on the upper floors to evacuate safely.

“Many of the enhancements implemented at the World Trade Center have now been incorporated into the New York City Building Code but these were new ideas at the time,” Nicole Dosso, director of SOM’s technical department told Architecture Magazine.