Socialist Worker

How safe are skyscrapers?

by Paul McGarr
Issue No. 1767

AFTER THE horror in the US last week anyone who works in a skyscraper or high rise building will have fears about safety. The way the World Trade Centre towers collapsed was one of the most chilling aspects of the tragedy.

The devastation underlines fears that an accident, rather than deliberate terrorist assault, could lead to the collapse of any skyscraper. As the BBC points out, the World Trade Centre design was one of the best in the world. Many 'newer skyscrapers are constructed using cheaper methods' and could collapse much more quickly.

It is also obvious that evacuation procedures are not central to the way giant buildings are designed. There are not enough escape methods for the numbers of workers. Emergencies lead to confusion and misinformation. When the World Trade Centre was struck, some workers were told that the safest thing was to stay inside the tower-a disastrous error.

The key to the collapse was not the initial impact of the planes. The buildings were designed to withstand the force of even a bigger jumbo jet crashing. What brought the buildings crashing down was fire. That shows you do not need a suicide bomber with a plane to produce a disaster in a skyscraper.

Professor Chris Wise of London's Imperial College says, 'It was the fire that killed those buildings.' The towers, like all skyscrapers, were held up by a concrete-cladded steel core and frame. But steel melts at 800ûC, and weakens at even lower temperatures than that.

The giant fire created by the aviation fuel on the planes raised temperatures in the steel core of the World Trade Centre to over 1,000°C. That melted steel on the upper floors, and when those collapsed onto fire-weakened floors below they too crumpled.

As more floors collapsed, what structural engineers call a 'pancake' effect-the repeated hammering of floors collapsing from above-then crumpled the whole building floor by floor. The design of the World Trade Centre meant, at least, that the buildings collapsed vertically onto their own 'footprint'.

Many, many more people would have died if they had toppled sideways. This, structural engineers argue, is what would happen with most skyscrapers. There are real questions about the details of what happened in New York, and whether some deaths could have been avoided. Many firefighters were sent to certain death because it was inevitable that the fire would mean the towers would collapse. Structural engineer Professor John Knapton of Newcastle University argues, 'Mistakes were made. It sounds hard, but they shouldn't have gone in. If they did decide to take the risk they should have been pulled out after an hour.'

If fire was the cause of the collapse, there is a real question about every skyscraper in the world. One of the world's tallest buildings was almost toppled last year by a fire caused by something as small as an electrical fault. It started in the Ostankino TV tower in Moscow, 100 metres up the 540-metre tower. It blazed out of control, and internal firefighting systems failed. Steel cables melted in the heat and stairs buckled. It doesn't take a terrorist bent on mass destruction and murder to crash a plane into a tall building. In 1992 an Israeli cargo plane lost control of its engines and smashed into a residential tower block on the outskirts of Amsterdam as it approached the city's Schipol Airport. Some 43 people were killed. Hundreds of people living on the estate have also been seriously ill since, because that Israeli plane was carrying deadly Sarin nerve gas in its cargo.

Every day in almost every major city in the world planes loaded with aviation fuel fly over built-up areas and high rise buildings and skyscrapers. London's City airport was closed last week, but it will soon reopen. It is barely a mile away from Canary Wharf, and the giant building is directly on many planes' approach path. Around the world governments and giant corporations are engaged in a competitive rush to throw up ever more giant skyscrapers. That rush has little to with any sane planning of cities and buildings, and everything to do with the symbolism of power and wealth in capitalism.

In the wake of last week's horror those behind this drive have serious questions to answer. Those who work in those buildings and firefighters who may have to deal with emergencies there want answers.


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Article information

Features
Sat 22 Sep 2001, 00:00 BST
Issue No. 1767
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