Emergency evacuation

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Emergency evacuation is the movement of persons from a dangerous place due to the threat or occurrence of a disastrous event. Examples are the evacuation of a building due to a bomb threat or fire and the evacuation of a district because of a flood or bombardment or an evacuation from a city due to a 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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Evacuation preparation

In areas threatened by disasters evacuation plans are established to prepare for an efficient evacuation and to avoid panic. Evacuation simulations, trials, and emergency plans are further measures of preparation.

The duration of an evacuation is called the evacuation time. There are several methods to forecast evacuation times such as full scale trials, calculations based on the flow of persons (hydraulic models) or evacuation simulations.

Reasons for evacuation

Evacuations may be carried out before, during or after natural disasters such as:

  • eruptions of volcanoes,
  • cyclones
  • floods, or
  • earthquakes.

Other reasons include:

  • military attacks;
  • industrial accidents;
  • traffic accidents, including train or airplane accidents;
  • fire;
  • bombings;
  • terrorist attacks.
  • military battles

Sequence of an evacuation

The sequence of an evacuation can be divided into the following phases:

  1. detection
  2. decision
  3. alarm
  4. reaction
  5. movement to an area of refugee or an assembly station
  6. transportation

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.

Evacuation of districts

The evacuation of districts is part of civil defense. Many of the largest evacuations have been in the face of war-time military attacks.

Contraflow lane reversal is a technique for speeding the mass evacuation of a district by road.

Evacuation of buildings

The strategy of individuals in evacuating buildings was investigated by Abrahams (1994). 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 is the one of motion impaired persons, who must be saved by nursing staff or first responders.

Evacuation of ships

The main difference between the evacuation of buildings and the evacuation of ships is the availability of an area of safety. The first phase, i.e., the assembly phase, of a ship evacuation is to some extent comparable to building evacuation. The evacuation to the boats (embarkation) starts after the assembly (at least for one assembly station) is completed.

Psychology of emergency evacuations

Despite mandatory evacuation orders, many people did not leave New Orleans as Hurricane Katrina approached. Most of the people stranded did not have personal transportation out of the city and left as soon as they were able, but others refused to be evacuated even as rescuers in boats tried to convince them to leave. "New Orleans rescues continue, but some won't go" NPR 9-6-05, "Rescuers urge residents to leave New Orleans" NPR 9-6-05

Why do people stay in the paths or wakes of natural disasters? Some people in New Orleans probably thought that as the city had survived decades of hurricanes, it would survive this one too. Others may not have realised how dire the consequences of remaining would be. In coastal Virginia, rescue workers hand markers to people who won't evacuate and tell them to write their social security number on their bodies so they can be identified. "Magic Marker strategy" New York Times 9-6-05

See also

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