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Model Building: An Examination of the Pre-evacuation Period of the 2001 WTC Disaster



Erica D. Kuligowski


This paper presents two models developed to describe the pre-evacuation period of the 2001 WTC Disaster. The first model is a conceptual model developed from performing a qualitative study of occupant behavior in response to the September 11, 2001 World Trade Center (WTC) disaster was performed. Through analyses of transcripts from 245 face-to-face interviews with survivors from both WTC towers, collected by Project HEED, a conceptual model was developed to describe the pre-evacuation period in what became the largest full-scale building evacuation in history was investigated. The objectives of this study were to understand the types of actions performed before occupants began evacuation via stairs and elevators and why those actions were taken to improve techniques used in evacuation modeling tools. On September 11, 2001, occupants consistently developed new social norms and lines of action based upon the meanings that occupants assigned to the situation, including perceptions of risk, familiarity with the building and others in the building, and responsibility for others. These meanings were dependent upon the receipt of environmental cues as well as on pre-existing norms, experiences, training, and social roles. The second model is a quantitative model, developed based upon the conceptual model, which can be used by current computer evacuation models to predict the evacuation decision-making during the pre-evacuation period of the 2001 WTC disaster. The quantitative model is built on the main assumption that risk perception is the key factor to simulate when predicting the timing of the evacuation decision, and uses this value to predict whether the simulated occupant is in the “normal” stage, “investigating” state, or “evacuating” state.
Fire and Materials


evacuation modeling, World Trade Center, egress, pre-evacuation, risk perception


Kuligowski, E. (2015), Model Building: An Examination of the Pre-evacuation Period of the 2001 WTC Disaster, Fire and Materials (Accessed May 24, 2024)


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Created June 8, 2015, Updated February 19, 2017