Skip to main content
U.S. flag

An official website of the United States government

Dot gov

Official websites use .gov
A .gov website belongs to an official government organization in the United States.


Secure .gov websites use HTTPS
A lock ( ) or https:// means you've safely connected to the .gov website. Share sensitive information only on official, secure websites.

Active Fire Protection Systems. Federal Building and Fire Safety Investigation of the World Trade Center Disaster (NIST NCSTAR 1-4) ***DRAFT for Public Comments***



D D. Evans, Erica D. Kuligowski, William S. Dols, William L. Grosshandler


The National Institute of Standards and Technology investigation of active fire protection systems in World Trade Center (WTC) 1, 2, and 7 included the design, installation, capabilities, and performance on September 11,2001, of the automatic fire sprinkler, standpipe, standpipe preconnected hoses, fire alarm, and smoke management systems. The purpose and normally expected performance of each active fire protection system in the buildings are described, as well as details about the systems installed in WTC 1, 2, and 7. Using fire protection engineering methods, the capabilities of the installed systems to respond to various fire threats from normal office fires up to and including the extraordinary challenge of the fires ignited by the aircraft impacts on September 11, 2001, were assessed. Information from the Fire Department of the City of New York records was used to document the history of significant fire events in WTC 1, 2, and 7. Findings of the investigation are presented with regard to the fire suppression, fire alarm, and smoke management systems installed on the day the buildings collapsed.
National Construction Safety Team Act Reports (NIST NCSTAR) - 1-4
Report Number


World Trade Center, high rise buildings, building collapse, disasters, fire safety, fire investigations, terrorists, terrorism, fire protection, fire alarm systems, fire protection engineering, smoke detection, smoke management, sprinklers, communication networks, hydraulic calculations, smoke purge, voice communication, fire hoses
Created September 1, 2005, Updated February 19, 2017