The hurricane seasons of the past few years produced vivid images of major highways filled to capacity with residents evacuating from coastal areas. Other less-widely publicized evacuations take place on a relatively frequent basis across the United States each year. A January 2005 study commissioned by the Nuclear Regulatory Commission cites that evacuation of 1,000 or more individuals occurs once every three weeks in this country.1 The study, which evaluated evacuation operations over a 12-year period, indicated that most evacuations result from wildfire threats to populated areas, floods, hurricanes and tropical storms, fixed site and transportation-related industrial accidents where airborne releases of gases often dangerous to humans occur, transportation accidents, and malevolent acts. During these scenarios, emergency responder assessments of the situation may prompt the incident commanders to ask law enforcement officials, often supported by transportation agencies, to order nearby residents to leave immediately. These events typically involve the evacuation of small towns or areas around industrial complexes. Dozens to maybe a few thousand people get in the family cars and drive a few miles to a safer location, directed away from the potential hazard area by law enforcement officers and traffic barriers which also prohibit any incoming traffic.
The September 11, 2001, (or 9/11) attacks on the high-profile workplaces of the World Trade Center (WTC) in New York City and the Pentagon, just outside Washington, D.C., made real the impact of an unexpected, or “no-notice,” event in a metropolitan setting. The news coverage of the events of this infamous day showed thousands of people leaving the area of the WTC on foot. The evacuation from the borough of Manhattan included not only the typical traffic congestion expected in an evacuation in the United States, but thousands of pedestrians moving along with, or among the streams of outbound and inbound vehicles. Even though numerous emergency response vehicles arrived at the WTC complex almost immediately, hundreds of others continued to converge on the immediate scene from more distant locations. When the Pentagon also was hit, national news coverage included pictures of the highways near the Pentagon filled with barely moving vehicles, much of it having originated in the District even before the Pentagon was evacuated. That morning the local and federal transportation agencies in the District were first-hand witnesses to the thousands of persons leaving government and other office buildings filling sidewalks to capacity. In places, they were spilling into the gridlocked traffic in order to make better progress or cross to take a different route.
When a large-scale, damaging event has occurred or the imminent threat of one has become known, transportation agencies working with public safety officials have traditionally had two principal objectives:
Evidence that large numbers of pedestrians may be part of an evacuation raised questions within FHWA about what actions are needed to manage pedestrian traffic during metropolitan evacuations and what FHWA can contribute in this area to ensure safe and effective movement of pedestrians while minimizing their impact on vehicular movement. While the U.S. has not experienced large scale, “no-notice” urban evacuations, emergency managers responsible for urban areas understand the potential for this type of evacuation to occur following natural, industrial, or malicious emergency events. Planners continue to look to the limited U.S. experiences of evacuations in response to no-notice events in cities to uncover lessons learned, findings and best practices to use in their efforts to plan for the worst and hope for the best. These instances include the NYC and Washington, D.C., 9/11 evacuations, the Oklahoma City bombing spontaneous evacuations, the Atlanta Summer Olympics bombing, and the movement resulting from the Northeast Blackout of 2003. FHWA is trying to aid planners by studying this often-overlooked component of evacuation to aid metropolitan evacuation planners in their efforts to balance the safety and mobility needs of both vehicle and pedestrian evacuees.
The reader should consider this report a cursory view of the topic. This report addresses what is already known about managing pedestrian traffic in U.S. metropolitan evacuations. Researchers tapped a large variety of information sources for insights. Since this is a very new area of research on evacuation, little actual research on the topic exists. A more complete definition of the issues necessitates further in-depth research on temporary evacuations from large highly urbanized city centers in reaction to a sudden unanticipated event, something that has rarely occurred in the U.S.
The term “metropolitan evacuation” here refers to an emergency evacuation taken as a protective action that is implemented for a portion of a densely built-up downtown area in larger cities in the United States. The basic situation assumed for the discussion of the issues is the following:
The report is organized as follows: