Response Phase Behaviours and Response Time Predictors of the 9/11 World Trade Center Evacuation

The evacuation of the World Trade Center (WTC) Twin Towers on 9/11 is one of the largest full scale high-rise emergency evacuations to date and provides an opportunity to learn from survivor experiences. Here, quantitative and qualitative data extracted from the UK WTC High-rise Evacuation Evaluation Database (HEED) study were used to: (i) calculate more fine-grained response times useful for evacuation modelling; (ii) investigate Response Phase behaviours; and (iii) see which of these behaviours and other factors predicted the response times. Analyses revealed that the majority of participants’ response times were within 0 min to 1 min of WTC1 being hit (rapid responders) and 1 min to 4 min (moderate responders). Logistic regression indicated that rapid responders were more likely to be participants in WTC2 than participants in WTC1, the tower that was currently under attack. Higher perceived risk and undertaking fewer if any tasks prior to evacuation also significantly predicted rapid response times. Conversely, response times beyond 1 min from WTC1 impact were significantly predicted only by increased numbers of Information Tasks being undertaken prior to evacuation. These tasks appeared to be undertaken more frequently prior to evacuation than were Action Tasks.