Fire experts to examine safety regulations

The focus of the efforts would be designing building so that occupants had sufficient time to evacuate after catastrophic event.

David Sugden, Chief Executive of the Association of Specialist Fire Protection said that structural steelwork in tall buildings was currently required to survive for two hours at temperatures of 900-1000ºC.

The fire at the WTC was a hydrocarbon fire with temperatures reaching 1200ºC. Sugden said: "I would guess the steelwork was not designed to withstand that type of fire."

It is possible to protect steel to these higher temperatures for periods of up to four hours and withstand an initial blast. However, this adds a fire protection cost of anything from 10% to 300%, depending on the fire protection technique chosen.

Meanwhile, Riba president Paul Hyett has called for a joint working group to be set up to examine the implications of the collapse of the World Trade Centre.

Now is the time to think about improvements

Paul Hyett, RIBA president

He said: "Tall buildings have incredible safety records, but the fire that took hold at the World Trade Centre was of an extraordinarily high temperature. Now is the time to think about further improvements to protect against such cataclysmic events".

Hyett is inviting the Institution of Civil Engineers, the Chartered Institution of Building Services Engineers and the Fire Protection Association, among other institutions, to join the group. The ICE said it welcomed the initiative.

A spokesperson said: "The ICE values working with a multidisciplinary group and will endeavour to contribute its expertise to the joint working groups that have been proposed in the wake of the twin towers disaster, including working with the American Society of Civil Engineers".

Engineering consultant Arup is setting up an "extreme events mitigation taskforce". This will take a multidisciplinary approach to examining the structure, fire protection and blast protection of buildings, and establish what can be done in the future.

David Glover, a structural engineer at Arup said that although the fire caused the collapse of the towers, they coped well with the impact of the plane. He said the issues that would be looked at included whether tall buildings should have concrete cores, and the need for greater levels of fire protection.