What Is a Mandatory Evacuation?

Emergency management officials use mandatory evacuations as a protective action to help save lives in certain emergencies. Because of their complex nature, a safe and efficient mandatory evacuation depends on the efforts of both authorities and evacuees themselves.

Mandatory Evacuation Causes

• Authorities call for mandatory evacuations only when a disaster has the potential to cause severe loss of life and damage to property and when safety can be found at a distance from the emergency. Examples of emergencies meeting these criteria include floods, toxic gas releases, wildfires and mudflows.

Evacuation Warnings

• Emergency management officials most often rely on commercial media sources to alert communities about evacuations. However, this method fails to notify people not tuned in to the radio or television, the homeless, speakers of foreign languages and disabled populations such as the deaf. Alternate warning methods include face-to-face contact, broadcasts from moving vehicles and sirens. Some emergency management offices also have reverse-911 capabilities, which allow officials to send alerts and information into the community through the phone system.

Evacuee Numbers and Transportation

• For smooth evacuations, authorities must consider the number of individuals evacuating and how they will leave the area. As explained by Lindell, Prater and Perry, "research has identified the household as the basic unit of evacuation." Therefore, officials can use population figures to estimate the number of households in the affected area and judge how many evacuees will be involved in the evacuation. While most households will evacuate using personal vehicles, many households lack personal transportation or have mobility limitations that require transportation assistance. Therefore, authorities must also provide public transportation for these evacuees, up to 1/3 of the population in some cities.

Spontaneous Evacuations

• Because most disasters affect only limited areas, authorities may call for mandatory evacuations only from the affected areas or request evacuations from the most severely impacted areas first and other areas at a later time. Ideally, the entire population in the mandatory evacuation areas will actually leave and people in low-risk areas will stay at home. Spontaneous evacuations---people leaving low-risk areas against official recommendations---range from 20 to 50 percent of some communities. They complicate evacuations by increasing the number of evacuees and vehicles, crowding evacuation routes and reducing the number of available shelter alternatives.

Evacuation Routes

• Given a choice, evacuees will use the most familiar routes during a mandatory evacuation, especially interstate highways. However, authorities may request they use alternative routes to reduce congestion and improve evacuation speeds. Evacuees should always cooperate and follow official instructions to prevent difficulties during the evacuation.

Mass Care

• When officials call for a mandatory evacuation, they also call on pre-existing shelter arrangements in outlying areas. Most evacuees prefer to stay with friends or relatives or in hotels, but between 3 and 20 percent will require mass care. Volunteers and staff members of various organizations such as the American Red Cross, Salvation Army and United Way set up reception centers, housing locations and feeding schedules for evacuees and their pets as soon as possible after learning about the evacuation.