The National Institute of Standards and Technology recently presented findings from its building and fire safety investigation of the World Trade Center disaster of Sept. 11, 2001. The findings include the probable collapse sequence of the towers, updating hypotheses previously released by NIST. The report also contains lessons learned from three other projects: analysis of building and fire codes and practices; occupant behavior, egress, and emergency communications; and fire service technologies and guidelines.

Recommendations for improvements to building and fire codes, standards, and practices derived from these and the other five projects in the investigation have been released for public comment. Copies of the presentation, draft reports, and all previous WTC investigation findings are available at http://wtc.nist.gov.