Provides details of the technical progress made since the May 2003 progress report on the World Trade Center (WTC) Investigation. The report includes a comprehensive summary of interim findings and accomplishments for each of the independent investigation objectives. Highlights include key visual observations on building, fire, and smoke conditions in the WTC towers and WTC 7 from the large collection of photographic and video images; progress on building and fire code analysis; major progress in building comprehensive models for analyzing the most probable collapse sequence from aircraft impact to collapse initiation. Progress has also been made in experimental/field work to analyze the recovered WTC steel, fire dynamics and thermal modeling, and fire endurance testing as well as the investigation of the design, capabilities, an dperformance of the active fire protection systems for the towers and WTC 7. First-person interviews have been completed, and early results of data analysis are presented; an analysis of emergency communications is also included. Interim reports are included on the inventory and identification of the recovered steel from the towers and on the study of the contemporaneous structural steel specifications.
Special Publication (NIST SP) - 1000-5
building research, building technology, collapse, evacuation, fire research, fire service, metallurgy, World Trade Center