Emergency evacuation is the immediate and rapid movement of people away from the threat or actual occurrence of a hazard. Examples range from the small scale evacuation of a building due to a bomb threat or fire to the large scale evacuation of a district because of a flood, bombardment or approaching hurricane. In situations involving hazardous materials or possible contamination, evacuees may be decontaminated prior to being transported out of the contaminated area.
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Evacuations may be carried out before, during or after natural disasters such as:
Other reasons include:
Emergency evacuation plans are developed to ensure the safest and most efficient evacuation time of all expected residents of a structure, city, or region. A benchmark "evacuation time" for different hazards and conditions is established. These benchmarks can be established through using best practices, regulations, or using simulations, such as modeling the flow of people in a building, to determine the benchmark. Proper planning will use multiple exits and technologies to ensure full and complete evacuation. Consideration for personal situations which may affect an individual's ability to evacuate. These may include alarm signals that use both aural and visual alerts. Regulations such as building codes can be used to reduce the possibility of panic by allowing individuals to process the need to self-evacuate without causing alarm. Proper planning will implement an all-hazards approach so that plans can be reused for multiple hazards that could exist.
The sequence of an evacuation can be divided into the following phases:
The time for the first four phases is usually called pre-movement time.
The particular phases are different for different objects, e.g., for ships a distinction between assembly and embarkation (to boats or rafts) is made. These are separate from each other. The decision whether to enter the boats or rafts is thus usually made after assembly is completed.
The strategy of individuals in evacuating buildings was investigated by John Abrahams in 1994.[1] The independent variables were the complexity of the building and the movement ability of the individuals. With increasing complexity and decreasing motion ability, the strategy changes from "fast egress", through "slow egress" and "move to safe place inside building" (such as a staircase), to "stay in place and wait for help". The last strategy that is the notion of using a designated Safe Haven on the floor. This is a section of the building that is reinforced to protect against specific hazards, such as fire, smoke or structural collapse. Some hazards may have Safe Havens on each floor, while a hazard such as a tornado, may have a single Safe Haven or safe room. Typically persons with limited mobility are requested to report to a Safe Haven for rescue by first responders. In most buildings, the Safe Haven will be in the stairwell.
The evacuation of districts is part of disaster management. Many of the largest evacuations have been in the face of war-time military attacks. Modern large scale evacuations are usually the result of natural disasters. The largest peace-time evacuation in the United States to date occurred during Hurricane Gustav.
Despite mandatory evacuation orders, many people did not leave New Orleans, United States, as Hurricane Katrina approached. Even after the city was flooded and uninhabitable, some people still refused to leave their homes. [2][3]
The longer a person has lived in a coastal area, the less likely they are to evacuate. A hurricane's path is difficult to predict. Forecasters know about hurricanes days in advance, but their forecasts of where the storm will hit are only educated guesses. Hurricanes give a lot of warning time compared to most disasters humans experience. However, this allows forecasters and officials to "cry wolf," making people take evacuation orders less seriously. Hurricanes can be predicted to hit a coastal town many times without the town ever actually experiencing the brunt of a storm. If evacuation orders are given too early, the hurricane can change course and leave the evacuated area unscathed. People may think they have weathered hurricanes before, when in reality the hurricane didn't hit them directly, giving them false confidence. Those who have lived on the coast for ten or more years are the most resistant to evacuating. [1]
Since Hurricane Katrina, there has been an increase in evacuation planning. Current best practices include the need to use multi-modal transportation networks. Hurricane Gustav used military airlift resources to facilitate evacuating people out of the affected area. More complex evacuation planning is now being considered, such as using elementary schools as rally points for evacuation. In the United States, elementary schools are usually more numerous in a community than other public structures. Their locations and inherent design to accommodate bus transportation makes it an ideal evacuation point.
Most local communities maintain registries for special needs individuals. These opt-in registries help with planning, as those that need government evacuation assistance are identified before the disaster. Registries used after a disaster are being used to help reunite families that have become separated after a disaster.
In the United States a person cannot be forced to evacuate under most conditions. To facilitate voluntary compliance with mandatory evacuation orders first responders and disaster management officials have used creative techniques such as asking people for the names and contact of their next of kin, writing their Social Security Numbers on their limbs and torso so that their remains can be identified[4], and refusing to provide government services in the affected area, including emergency services.
   | Panic Simulation (Budapest University) - Panic: A Quantitative Analysis |
| | A Cellular Automaton Model for Crowd Movement and Egress Simulation - DuEPublico: A Cellular automaton model for crowd movement and egress simulation |
| | Fire Safety Engineering Group at the University of Greenwich - Fire Safety Engineering Group (FSEG) Home |
| | Dirk Helbing's homepage - ETH - Chair of Sociology, in particular of Modeling and Simulation - Chair of Sociology, in particular of Modeling and Simulation |
| | "Magic Marker strategy" New York Times 9-6-05 - Magic Marker Strategy - New York Times |
| | "New Orleans rescues continue, but some won't go" NPR 9-6-05 - New Orleans Rescues Continue, But Some Won't Go : NPR |
| | "Rescuers urge residents to leave New Orleans" NPR 9-6-05 - Rescuers Urge Residents to Leave New Orleans : NPR |
| | Evacuation routes for the US by state. - USA evacuation routes |
| | A bibliography for pedestrian simulation and evacuation dynamics - TraffGo HT, Pedestrians |
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