Occupant Behavior, Egress, and Emergency Communication. Federal Building and Fire Safety Investigation of the World Trade Center Disaster.
Occupant Behavior, Egress, and Emergency Communication.
Federal Building and Fire Safety Investigation of the
World Trade Center Disaster.
Averill, J. D.; Mileti, D. S.; Peacock, R. D.;
Kuligowski, E. D.; Groner, N.; Proulx, G.; Reneke, P.
A.; Nelson, H. E.
NIST NCSTAR 1-7; 298 p. September 2005.
World Trade Center; high rise buildings; building
collapse; disasters; fire safety; fire investigations;
terrorists; terrorism; building fires; egress;
communication networks; evacuation; human behavior
2 on September 11, 2001. Multiple sources of information
were collected and analyzed: over 1,000 new interviews
with survivors (including 803 telephone interviews, 225
face-to-face interviews, and 5 focus groups); over 700
published interviews; 9-1-1 emergency calls; transcripts
of emergency communications, historical building design
drawings, memoranda, and calculations; formal complaints
filed with the Occupational Safety and Health
Administration; and other relevant materials. The egress
system, including stairwells and elevators, was
described and compared to requirement of both
contemporary and current code requirements. This report
documents the emergency procedures, both as they were
designed to be implemented, as well as how they were
actually implemented on September 11, 2001.
The population in WTC 1 and WTC 2 on September 11, 2001,
at 8:46:30 a.m. was enumerated and described, where the
characteristics of the population were relevant to the
subsequent evacuation, including training, experience,
mobility status, among others. The progress of the
evacuation of both towers was described in a
quasi-chronological manner from 8:46:30 a.m. when WTC 1
was attacked, until 10:28:22 a.m., when WTC 1 collapsed.
Causal models were built to explore the sources of
evacuation initiation delay (why people did not
immediately start to leave the building) as well as
normalized stairwell evacuation time (how long the
average occupant spent in the stairwells per floor).
Issues identified as contributing to either speeding or
aiding the evacuation process were explored. Egress
simulations provided context for estimating how long WTC
1 and WTC 2 would have taken to evacuate with different
populations, using different models, and subject to
different damage to the building.