Surveys and Analyses on Human Behavior in the New York World Trade Center Disasters in 1993 and 2001

Abstract

The World Trade Center in New York (WTC) was attacked by terrorists twice, in 1993 and 2001. In the latter case, it collapsed. In the first case on February 26, 1993, a survey was conducted holding interviews with Japanese business people. The testimonies are analyzed according to the number of occupants, occupants’ awareness of the emergency, pre-escape behaviors, behavior in the stairs, and escape time. In the second case on September 11, 2001, survivors’ stories were collected from the Internet. The remarkable and common event found in two disasters is heavy congestion in the stairs. This paper aims to study measures for life safety design to future tall buildings focusing on a heavy congestion in the stairs caused by simultaneous escape in the whole building. In analyzing a simultaneous escape, it is necessary to deal it with a dynamic method, as human flow in stairs is a feedback system. Analyses ofWTC escape standing on the same position are reported by NIST [1]. The fluid model in this paper was carried out prior to NIST studies and demonstrated necessity of dynamic analysis.

Numerical analysis and validation on the phased evacuation time in high-rise buildings

“…Especially after the disaster of WTC 9/11 that raised concerns about avoiding disorder, improving human life safety and the effectiveness of evacuation strategies in high-rise buildings. [1][2][3][4][5][6][7][8][9] Fire safety requirements in high-rise buildings are usually more challenging than in low-rise buildings since even a single fire may cause massive casualties, 5,10 resulting in raised concerns regarding the need for building fire safety regulations to ensure the timely evacuation of high-rise buildings. In addition, there are various ways of providing fire safety, from complying with regular prescriptive codes (PC) to specific measures such as fire engineering approach, performance-based designs and engineering performance-based fire codes for extraordinary buildings where the PC could be inadequate due to various reasons.…”