Emergency evacuation

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For other uses, see Evacuation.
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Evacuees on Interstate 45 leaving Galveston during Hurricane Rita in 2005.

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.

Contents

[edit] Reasons for evacuation

Evacuation route sign on Tulane Avenue in New Orleans.

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

Other reasons include:

[edit] Planning

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.

[edit] Evacuation sequence

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 refuge 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.

[edit] Small scale evacuations

A sign mandatory for buildings in the United States, showing the way to the nearest exit, with two emergency lights for electrical failure.

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 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.

[edit] Large scale evacuations

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.

[edit] Improvements in evacuation systems

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[edit] Public transportation

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.

[edit] Registries

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.

[edit] Enforcing Evacuation Orders

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[1], and refusing to provide government services in the affected area, including emergency services.

[edit] Hurricane evacuations

 It has been suggested that this section be split into a new article entitled Hurricane Evacuations. (Discuss)

[edit] Sociology of hurricane evacuations

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]

[edit] Reasons people do not evacuate

[edit] Experience

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]

[edit] Traffic

Even if one does have a car, it may not be an efficient means of evacuating. The traffic jams that thousands of motorists experienced in South Carolina while fleeing Hurricane Floyd and Texas while fleeing Hurricane Rita exemplify the frustration of people trying to evacuate. Some jurisdictions have implemented contraflow lane reversal plans in an attempt to increase outbound traffic capacity from coastal areas, but traffic jams remain a fact of life in these situations. [2]

[edit] Limited social capital

Social capital refers to the connections between people: social networks and the reciprocity and trust within them. The social systems of communities can have a large impact on their ability and willingness to evacuate. Weak social networks within a community can make evacuation difficult. If people don't trust each other, then they are likely to fear that their homes or stores will be looted if they evacuate. Communities that have the physical capital, such as cars, to evacuate everyone may not have the social capital to facilitate sharing these resources. However, strong social networks within a community can also hinder evacuation by increasing the ties to the neighborhood and refusing to evacuation. [3]

[edit] Evacuation Zones

Some jurisdictions, such as Pinellas County, FL use the output from the SLOSH storm surge model developed by FEMA to create their evacuation zones. These zones loosely correspond to the maximum expected storm surge expected during a category of a hurricane. Since these evacuation maps are used by the general public and a more static nature is desirable, some minor averaging or ranging of data is performed before creating the maps. Changes in variables such as mean high-tide, forward speed and direction of the hurricane, and central pressure all affect the output of the SLOSH model.

[edit] See also

[edit] References

  1. ^ "Magic Marker strategy" New York Times 9-6-05
  2. ^ "New Orleans rescues continue, but some won't go" NPR 9-6-05
  3. ^ "Rescuers urge residents to leave New Orleans" NPR 9-6-05
  • Abrahams, John: "Fire escape in difficult circumstances", chapter 6, In: Stollard, 1994, "Design against fire".
  • Gershenfeld, Neil, Mathematical Modelling. OUP, Oxford, 1999.
  • Hubert Klüpfel, A Cellular Automaton Model for Crowd Movement and Egress Simulation. Dissertation, Universität Duisburg-Essen, 2003.
  • Stollard, P. and L. Johnson, Eds., "Design against fire: an introduction to fire safety engineering design", London, New York, 1994.

[edit] External links

Retrieved from "http://en.wikipedia.org/wiki/Emergency_evacuation"
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