News : Cover story
Gordon Masterton, chairman of the ICE structural and building board, was in urgent demand by the national media to comment on the collapse of the twin towers.
On Tuesday 11 September, during a routine Council meeting at One Great George Street, I was called out by the ICE’s communications director. The words he spoke barely sank in, and left a gnawing ache in the pit of my stomach.
Two planes had struck the twin towers of the World Trade Centre.
As chairman of the structural and building board, would I speak to the media who were hungry for information?
The next few hours were spent talking to journalists, science correspondents and radio presenters trying to offer an engineering perspective on the unthinkable events as they unfolded.
In one of the interviews, as I heard my voice describe the likely sequence of events which led to the final catastrophic collapses, I realised I was speaking words which no civil engineer would ever want to speak. This was no ‘whatif’ scenario. This was no simulation for a risk assessment. This had happened. This was real. Two of the largest structures in the world had been rendered into rubble in the space of an hour and a half.
That day, the confidence we placed in our basic building blocks of civilisation - the lasting, permanent achievement we display and celebrate in our built environment - was shaken to the roots. Our peacetime cities, which represent the energy and vibrancy of a flourishing culture, were shown to be vulnerable to a shocking act of terror.
How should we, as engineers, react? What can WE do to help the world come to terms with this attack? I am sure I am not alone in having an instinctive first reaction that we must ensure that our tall buildings are made so robust and impregnable that they will shrug off any such attack in the future. But let us think this through. It was not the first strike that felled the towers.
The planes slammed into the buildings but broke up on impact so that they were almost surreally absorbed. The towers barely flinched. The plane engines would do significant local damage, but the rest of the plane would be sliced into pieces by the steel boxsection columns of the towers.
The fatal damage was done by the plane debris and 30 tonnes of aviation fuel being hurled into the open plan floors of the building in a 1,000degreesC fireball, starting an inferno which was way beyond the capacity of a sprinkler system.
These systems are designed to douse fires fuelled only by furniture and fittings. And burning planes need foam to fight them, not water.
How could we prevent that? By designing buildings with windowless, dense, impermeable armour-plating? But who wants to live or work in a nuclear bunker in the sky? Even if we could, or would, armour plate our tall buildings, what about lower height targets? The Houses of Parliament, Buckingham Palace, St Paul’s Cathedral. All of them powerful symbols of our nationhood. Do we clad these in armour plate?
Living in cities with buildings that we admire and enjoy, and which in turn inspire us, is one of our basic freedoms. We cannot and should not rush in to re-examining our building techniques. We cannot react to the events in New York by cowering away in darkened bunkers. We must not turn our cities into fortresses. That in itself would be a victory for terror.
So, while there may be lessons from the World Trade Centre attack (and this may lie in providing much more robust protection to the means of escape), we should not expect our buildings to perform miracles. Civilian airliners in the hands of suicidal fanatics are deadly and terrible weapons capable of delivering mass destruction.
But even if we developed buildings impregnable to Boeing 747s, would not terrorists turn to other means of delivery of whatever warped message they want to deliver? Poisoning the water supply? Biological warfare?
As engineers our best response is to keep a measured, calm perspective on the events of Tuesday. Skyscrapers have served us very well indeed. They are a success story. Hundreds of thousands of people live and work in them throughout the world, and deserve to continue to feel secure.
The measured approach to this particular risk is not to try to anticipate targets of a future terrorist attack and make them impregnable. The targets and nature of attacks would simply then be changed. Terrorists attack the soft underbelly of civilisation. The measured approach is to minimise the risk of recurrence of any trigger event to as close to zero as we can. This is an issue of security, of politics, of the resolution of deep conflicts.
Fortress cities are not the answer to terrorism. For humanity’s sake, let’s hope we find one.