Warning and evacuation: answering some basic questions

In this paper we address five questions that are frequently asked in the con-text of emergency planning for various accidents and disasters. These ques-tions are commonly voiced by emergency managers or planners wanting a bet-ter basis for developing emergency response plans. The questions are frequently answered by people who have an image of how people behave in an emergency; often, however, their observations are inaccurate and misleading. The ques-tions are as follows. First, how long does it take to warn a population about a crisis? Second, how many people evacuate in an emergency situation? Third, when do people evacuate? Fourth, do people evacuate unnecessarily? Fifth, where do people go when they evacuate? The major findings are as follows. First, most emergency response systems, which typically consist of law enforcement, firefighting and other civic employ-ees, and sometimes volunteers, coupled with emergency use of available elec-tronic media, can issue an effective warning given three or four hours of lead time. In some situations, when the threat is urgent, a warning can be dissemi-nated in a much more rapid fashion. In situations with less than one hour of available warning time, some, and perhaps a substantial portion of the popu-lation will not receive a warning. Second, the speed of warning dissemination, particularly in urgent situa-tions, is increased by informal warning processes. People seek information fol-lowing the receipt of the warning and one common way to do so is to contact