A C E C 2 0 0 4 E N G I N E E R I N G E X C E L L E N C E AWA R D W I N N E R S GRAND CONCEPTOR AWARD WINNER WEIDLINGER ASSOCIATES, INC. New York, N.Y. World Trade Center Forensic Study FORREST MACCORMACK Of the countless uncertainties and fears generated by the tragic events of September 11th, the question of why the World Trade Center Towers collapsed was in need of definitive answers, not just theory. A multi-disciplinar y project team studied original engineering drawings, assembled thousands of photos The Grand Conceptor Award and videos and generated sophisticated computer simulations to reconstruct the exact manner in which is presented annually to honor the buildings collapsed. Among the study's conclusions was the determination that the towers were robust the best overall engineering enough to resist the airplane impacts, but were fatally weakened by subsequent fires in the impact zones. achievement by a design firm. The team also determined that each tower collapsed in a unique way, and the collapse of the South Tower neither caused nor contributed to the collapse of the North Tower. The study serves as a bench- mark for the construction of safer buildings, especially in dense urban environments, and promises to influence change to current building code standards throughout the nation. l June 2004 2 8 E N G I N E E R I N G INC. M a y