December 2003 Public Update on the Federal Building and Fire Safety Investigation of the World Trade Center Disaster (NIST SP 1000-4)
Summarizes World Trade Center (WTC) investigation activities since the May 2003 progress report. Access has been obtained to nearly all of the important information needed for the investigation. The selection process for all major contractors and experts is completed. Progress has been made toward building comprehensive models for analyzing the most probable structural collapse sequences. Progress has also been made in the collection and analysis of images to document the evolution of fire and smoke conditions and damage to the WTC buildings. A status is provided of the first-person data collection effort involving WTC occupants, families of victims, and first responders. Status is also provided on the analysis of building and fire codes and practices as well as on the installed active fire protection systems. An update is given on the research and development related to the WTC investigation.