Assumptions on evacuation times are too optimistic says new study

摘要

People do not react quickly in evacuating a building in an emergency, according to new research conducted with survivors of the 9/11 attack on the World Trade Centre towers. Researchers from the Universities of Greenwich, Ulster and Liverpool have completed a three and a half year study into the evacuation of the twin towers. Interviews with 271 survivors generated 6,000 pages of first hand accounts of what it was like as they tried to leave the buildings. Preliminary findings include: 1. more than half the occupants stayed to carry out tasks before evacuating 2. occupants seeking information about what was happening took between 1.5 and 2.6 times longer to respond 3. congestion on the stairs was the main cause of delay, even though the towers were less than one-third occupied that day 4. computer simulations of the evacuation of the North Tower suggest that had the building been fully occupied at the time of the attack, some 7,592 people would have died in the North Tower alone 5. computer analysis suggests that for buildings above a critical population and height, stairs alone will not be sufficient to safely evacuate the entire building population.