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.

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,
• nuclear accident
• traffic accidents, including train or aviation accidents,
• fire,
• bombings,
• terrorist attacks
• military battles
• viral outbreak

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 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.

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. An emergency evacuation details the situation to be ready for use by all particpants at all times.

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.

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.

• "New Orleans rescues continue, but some won't go" NPR 9-6-05,
• "Rescuers urge residents to leave New Orleans" NPR 9-6-05

Reasons people don't evacuate

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]

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. In response, the Virginia Department of Transportation is currently upgrading Interstate 64 by installing hurricane gates so the east-bound lanes would close and be used as west-bound routes (see contraflow lane reversal) in the event of a mass evacuation of the Hampton Roads area. [2]

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. Weak connections with people in other regions of the country also make evacuating difficult: if you don't have friends or family you can stay with, you'll have to find and pay for a hotel room. However, strong social networks within a community can also hinder evacuation: if a person has strong ties to their neighbors but not to anyone outside that small community, they are more likely to stay where they are, with the people they can rely on, rather than evacuate and leave their social network. [3]

Shelter-In-Place

Sheltering-in-place is an alternative to evacuation that can be cost-effective and save lives.

Suggestions for improving evacuation systems

Public transportation

A bussing plan needs to be in place so that people who don't own vehicles are able to evacuate. These plans need to be worked out and publicized well before the threat of a hurricane. Bussing would be most effective if there was an easy-to-remember meeting place--for example, every elementary school could be a designated pick-up area.

Find out who will need assistance

The city should know who is likely to need help during an evacuation. Before every hurricane season, the city should canvass its citizens to find out who doesn't have a car, who has health problems that would make travel difficult, and who doesn't have a place to go or money to pay for a hotel. People would report where they would be likely to go during an evacuation, so that officials could better anticipate traffic patterns. Those who were elderly or disabled would report whether they had friends who could help them evacuate, so that aid workers would know who was likely to be alone and in need of assistance. Public transportation could be planned for, based on where the need was greatest, and officials would know where they needed to concentrate their evacuation education efforts. The need for shelters and hotel rooms could be predicted, so that the facilities could be prepared to serve evacuees. The older adult, in particular, would need additional consideration during an evacuation in a disaster. Pre-existing conditions such as impaired mobility, diminished sensory awareness and confusion can present major disadvantages in an emergency situation. Therefore, outreach programs that understand and respond to the special needs of the older adult in the area of public health preparedness and disaster readiness are urgently needed.

Help evacuees find each other

In New Orleans, many families were separated and had no way of finding each other. A website made specifically to help people find each other could provide peace of mind for many. A person could post a simple profile listing their location and contact information. Their family and friends could search for their name or home address to find them. Of course, internet access can be hard to come by during emergencies, but this would be better than nothing, and computer stations could be set up at shelters so that people could update within a reasonable amount of time. This website should be highly publicized, so that even people who were not tech-savvy would know about it. It would have to be well-designed so that even people who had no computer experience could navigate it. It would also need a reliable server that wouldn't be overwhelmed during heavy use. After Katrina, there were many places on the internet where do-gooders listed housing offers, but these resources could have been better utilized if they were consolidated into one easy-to-navigate site that evacuees knew about.

Convince people to leave

In coastal Virginia, rescue workers gave hand markers to people who wouldn't evacuate, and told them to write their social security number on their bodies so they could be easily identified. "Magic Marker strategy" New York Times 9-6-05

See also

• Civil defense
• Evacuation simulation
• Historical examples of large/mass evacuations of areas

References

• 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.

External links

• The International Emergency Management Society
• A bibliography for pedestrian simulation and evacuation dynamics
• Fire Safety Engineering Group at the University of Greenwich
• PESOS and BYPASS, reasearch projects concerning the "Evacuation of Passenger Ships" (University Duisburg-Essen, Germany)
• Panic Simulation (Budapest University)
• Dirk Helbing's homepage
• City evacuation study, Tokyo Institute of Technology
• Decontamination - prior to evacuation where possible.
• Evacuation routes for the US by state.