When the twin towers of theWorld Trade Center were attacked on September 11, 2001, thousands of people were able to evacuate the complex before the buildings collapsed. This paper describes the evacuation of the two towers, based on an analysis of first-person accounts that began to appear in the media immediately after the incident. In all, accounts from 435 survivors who were present in the towers at the time of the attack were reviewed. Using a questionnaire adapted from a study of an earlier evacuation of the towers in 1993, the accounts were ‘interviewed.’ Results of the analysis provided information on the location of occupants, their initial awareness of events, the conditions and obstacles they encountered during their evacuation and the time taken to evacuate. The evacuation is compared to events in 1993. Other studies of the evacuation in 2001 are described briefly.

1. [1] J. Averill et al., “Federal Building and Fire Safety Investigation of the World Trade Center Disaster – Occupant Behavior, Egress, and Emergency Communication,” NIST NCSTAR 1-7, National Institute of Standards and Technology, Gaithersburg MD, 2005.
2. [2] Federal Emergency Management Agency (FEMA), “World Trade Center Building Performance Study: Data Collection, Preliminary Observations, and Recommendations,” FEMA 403, Federal Insurance and Mitigation Administration, Washington DC, 2002.
3. [3] D. Cauchon, “For many on Sept.11, survival was no accident,” USA Today, December 19, 2001.
4. [4] R. Fahy and G. Proulx, “Federal Building and Fire Safety Investigation of the World Trade Center Disaster – Analysis of Published Accounts of the World Trade Center Evacuation,” NIST NCSTAR 1-7A, National Institute of Standards and Technology, Gaithersburg MD, 2005.
5. [5] J. L. Bryan, “Behavioral Response to Fire and Smoke,” SFPE Handbook of Fire Protection Engineering, Third Edition, Chapter 3-12, NFPA, Quincy MA, pp. 3-315 - 3-341, 2002.
6. [6] R. L. Best, “Reconstruction of a Tragedy – the Beverly Hills Supper Club Fire, Southgate, Kentucky, May 28, 1977,” National Fire Protection Association, Boston MA, 1977.
7. [7] T. J. Shields, K. Boyce, and G. Silcock, “Towards the characterization of large retail stores,” Proc. of the First Int. Symposium on Human Behaviour in Fire, University of Ulster, pp. 277-289, 1998.
8. [8] B. Latane and J. Darley, “Group Inhibition of Bystander Intervention in Emergencies,” J. of Personality and Social Psychology, Vol.10, No.3, pp. 215-221, November, 1968.
9. [9] M. S. Isner and T. J. Klem, “Fire Investigation Report – World Trade Center Explosion and Fire, New York, New York, February 26, 1993,” NFPA unpublished report.
10. [10] R. F. Fahy and G. Proulx, “Human Behavior in the World Trade Center Evacuation,” Fire Safety Science: Proc. of the Fifth Int. Symposium, Int. Association for Fire Safety Science, 1997.
11. [11] R. R. M. Gershon et al., “Preliminary results from the World Trade Center evacuation study-New York, 2003,” Centers for Disease Control and Prevention Morbidity and Mortality Weekly Reports, 55(35), pp. 815-816, 2004.
12. [12] R. R. M. Gershon, “The World Trade Center Evacuation Study: Factors Associated with Evacuation Time and Injury,” Proc. of the 4th Int. Symposium on Human Behaviour in Fire, Interscience Communications, Ltd., London, 2009.
13. [13] E. R. Galea et al., “The UK WTC 9/11 Evacuation Study: an Overview of the Methodologies Employed and some Preliminary Analysis,” Proc. Pedestrian and Evacuation Dynamics 2008, Ed: W.W.F. Kligsch et al, Springer-Verlag Berlin Heidelberg, pp. 3-24, 2010.