MEGATOWER EVACUATION procedures will have to rely more heavily on the use of lifts as a result of last month's World Trade Center (WTC) disaster, a leading tall building designer claimed this week.
Connell Mott MacDonald managing director John Leuchars said that escape stairs in many towers were unable to cope with mass evacuations after major disasters.
'Increasing the size of the stairwells is neither practical nor economically viable, ' he added.
'Instead, we will have to consider doing what has always been seen as unsafe - using lifts as the prime means of escape.'
Many survivors of the 11 September tragedy are reported to have owed their lives to the unusual three tier lift installations in the two WTC towers.
Lifts serving the lower floors were initially unaffected by the aircraft impacts. As a result some office workers ignored official emergency procedures and used the lifts to escape.
Leuchars said that Connell Mott MacDonald was researching the potential for lift assisted escape using an in-house developed computer programme which models human behaviour in emergency situations. 'There is a huge escape capacity in the lifts, provided they are properly protected, ' he said.
'With fire-rated lift doors at every floor, fire doors in the ground floor lobby and enhanced protection to the lift motor rooms, the lifts should be a safe escape route.'
Protecting the building's core was the key principle, Leuchars added. If the lifts and the escape stairs are kept clear of debris and smoke, and the fire risers were able to keep on functioning, mass evacuations would be much more risk-free.
Newcastle University professor of structural engineering John Knapton said: 'If you provided enough stair capacity to get everyone out of a very tall building in a short time the entire ground floor would be stairwells.'