Analysis of published accounts relating to the evacuation of the World Trade Center on 11 September 2001

Following the WTC disaster, the Building Disaster Assessment Group (BDAG) of the UK Office of the Deputy Prime Minister, funded the Fire Safety Engineering Group (FSEG) of the University of Greenwich to gather, collate, categorise, electronically store and finally analyse data concerning human behaviour during the WTC evacuation.

Two types of material were collected and analysed, the results for which are presented in two separate reports.

REPORT 1: Collection and Analysis of Human Behaviour Data appearing in the mass media relating to the evacuation of The World Trade Centre Towers of 11 September 2001.

REPORT 2: Collection and Analysis of Emergency Services Data Relating to the Evacuation of the World Trade Centre Towers of 11 September 2001.

REPORT 1 Overview:
Evacuation accounts were gathered from the literature published in the public domain. Material sources ranged from survivor accounts printed in newspapers and newspaper web sites, interviews in the electronic media, survivor web sites and books. Over 250 separate accounts were gathered that described occupant behaviour. Information appearing in print newspapers represents 70% of the accounts while information from websites (news and personal) represents 16% of the accounts. The remainder of the accounts have appeared in books, journals and the electronic media. These accounts provided information concerning 120 people from WTC1 (north tower or WTC1) and 119 from WTC2 (south tower or WTC2) and 21 of unknown origin.

The collected accounts were entered into a specially developed database. The database itself was designed to be a flexible qualitative research tool enabling the categorisation of occupants’ experiences during the data input process. As part of the data entry, the entire verbatim data account was stored. In addition, each individual experience described within the account were stored and assigned specific behavioural references. This is similar to traditional qualitative analysis tools that allow users to categorise portions of textual accounts during the input process. The database contains reference to a total of 3291 experiences from 260 people (1869 accounts from WTC1, 1411 from WTC2 and 11 from unknown locations).

In reviewing the findings of this report, it must be remembered that the data on which the analysis is based was not collected in a scientific manner but from accounts in the public domain, primarily press accounts. As such it is difficult to generalise many of the findings. However, as much of the data was reported days after the incident, it provides a unique and insightful glimpse into the human response to such emergencies. The key findings of this research may be found in Report 1. The results are presented under the following headings:

• OCCUPANT PRE-EVACUATON TIMES:

Of the 115 people who provided information on which a pre-evacuation time could be estimated, 60% responded within an estimated 5 minutes of the assault on WTC1 and some 13% took longer than an estimated 17 minutes to respond. Occupants in WTC2 responded quicker to the assault than occupants in WTC1 - the first tower to be attacked. This occurred in WTC2 despite instructions issued over the PA system in WTC2 instructing occupants that there was no need to evacuate WTC2.

• OCCUPANT PRE-EVACUATION ACTIONS:

(i) State of mind.
(ii) Nature of pre-evacuation actions.
(iii) Knowledge of the event:
(iv) Usage of telephones:
(v) Collecting Items:

• EVACUATION PHASE

(i) Flow conditions within the towers
(ii) Obstructions to flow
(iii) Usage of elevators as a means of evacuation in WTC2
(iv) Group Behaviour
(v) Stair Travel Speeds
(vi) Fire Wardens
(vii) Fatigue

This study has provided insight into the response of people subjected to extreme emergency conditions in high rise buildings. The information is useful in its own right in understanding how the evacuation of the World Trade Centre Towers evolved on 11 September 2001. More significantly, the insight gained will be useful in shaping our building codes and devising emergency procedures for evacuation. Furthermore, the information collected will be invaluable in assisting the development of behaviour models that are key components of evacuation models used in performance based building design and in providing data for model scenario specification.

The data collected and analysed in this study will be used as the starting point for a much larger project into the evacuation of the WTC. The project, called HEED – High-rise Evacuation Evaluation Database – funded by the UK EPSRC (project GR/S74201/01) and involving the Universities of Greenwich, Ulster and Liverpool, aims to interview 2000 survivors of the WTC twin towers evacuation.

Download Report 1: PDF 1.86 MB

REPORT 2 Overview:
Towards the end of 2003, FSEG obtained six PDF documents comprising approximately 5,000 pages of data relating to the WTC evacuation. This information consisted of:

• Four PDF documents of telephone and radio calls and conversations which occurred on the 11 September 2001 between New York and New Jersey Police agencies and callers.
• Two PDF documents comprised letters of commendation for individual Police Officers and an account of the incident by the Officer concerned.

BDAG requested that FSEG should enter this information into the database and analyse the information. The report focuses on the effectiveness of the emergency response and attempts to identify issues which might help future planning. The key findings of this research may be found in Report 2. The results are presented under the following headings:

(i) Recognition of the situation
(ii) Police logistical and tactical response
(iii) Evacuation of tower concourses
(iv) Police ascent of towers
(v) Emergency Equipment
(vi) Command Posts
(vii) Communications
(viii) Decision to evacuate the towers
(ix) Trapped occupants
(x) Locked exit routes
(xi) Telephone calls by and to the Police

This study has provided insight into the response of the rescue services operating under extreme emergency conditions in high rise buildings. The information is useful in its own right in understanding how the emergency services responded to the World Trade Centre disaster of 11 September 2001. More significantly, the insight gained will be useful in shaping our emergency procedures for evacuation.

Download Report 2: PDF 355 KB

Reference:
Collection and Analysis of Human Behaviour Data appearing in the mass media relating to the evacuation of the World Trade Centre Towers of 11 September 2001, Galea E.R and Blake S., University of Greenwich Fire Safety Engineering Group. A report prepared for the Building Disaster Assessment Group of the UK Office of the Deputy Prime Minister. 30/07/04.

Collection and Analysis of Emergency Services data relating to the evacuation of the World Trade Centre Towers of 11 September 2001, Galea E.R and Dixon A., University of Greenwich Fire Safety Engineering Group. A report prepared for the Building Disaster Assessment Group of the UK Office of the Deputy Prime Minister. 31/07/04.

See publications #162, 95