Final Report on WTC Towers Collapse Released

Oct. 27, 2005

Safety recommendations included in the National Institute of Standards and Technology report

On Oct. 26, 2005, William Jeffrey, director of the Commerce Department’s National Institute of Standards and Technology (NIST), testified before the House Science Committee on the findings and recommendations from NIST’s building and fire safety investigation of the World Trade Center (WTC) disaster on 9/11. At the same time, NIST released the final report of the 3-year investigation into the probable cause(s) of post-impact collapse of the WTC Towers and WTC 7. The report includes the following information:

  • How impact from jet fuel-laden aircrafts and subsequent fires led to the collapse of the towers.
  • Whether the fatalities were low or high.
  • An evaluation of building evacuation and emergency response procedures.
  • What procedures and practices were used in the design, construction, operation, and maintenance of the towers.
  • Current building and fire codes, standards, and practices that warrant revision.

The final report was compiled by NIST after consultation with private sector technical experts; study of copious documents, photographs, and videos of the disaster; computer simulations; as well as nearly 1,200 first-person interviews of building occupants and emergency responders.

Thirty recommendations are included in the report. These detail areas for improvements in structural integrity, enhanced fire endurance, new methods for fire resistant design, enhanced active fire protection, building evacuation, emergency response, procedures and practices, and education and training.

To read the final report in its entirety or review Dr. Jeffrey’s written testimony from the Oct. 26, 2005, hearing, visit (

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