Sandia LabNews

Sandia study looks at large-scale emergency evacuations

Sandia study looks at large-scale emergency evacuations

Refusal to evacuate is relatively common for hurricane evacuations, as opposed to other types of disasters, according to a recent Sandia study.

The study, conducted by Lori Dotson and Joe Jones (6874), is considered the most comprehensive study of large-scale evacuations in the US in more than 15 years.

“Interestingly enough, there were no refusals to evacuate for the terrorism-related evacuations that we studied,” says Lori.

The research, funded by the Nuclear Regulatory Commission, examined a total of 230 large-scale evacuations of more than 1,000 people during a 13-year period. It included evacuations due to natural disasters, technological hazards such as chemical spills, and terrorist events. Of these, 50 were studied in greater detail.

Lori says that even though the Sandia study primarily focused on the evacuations themselves, Hurricane Katrina has shown that the US needs to be better prepared for the aftermath of any event, whether it is natural, man-made, or terrorism-related. This includes properly planning for re-entry of the public following the event.

Data for the study were collected via questionnaire, a common method for this type of analysis, and advanced statistical methods were used to analyze the questionnaire responses. The research identified that community familiarity with evacuation alerting methods and door-to-door notification were key factors contributing to more effective evacuations.

Factors associated with the least effective evacuations included traffic accidents, deaths from the hazard, injuries during evacuation, people evacuating before being told to do so, people refusing to evacuate, and looting and vandalism.

One of the major conclusions of the study is that large-scale evacuations in the US, whether preplanned or ad hoc, are very effective and successfully save lives and reduce the potential number of injuries associated with the hazard. The research showed that in 26 (52 percent) of the events studied, a portion of the affected community refused to evacuate. This was quite common in hurricane events where residents live in the area and believe they understand the risk and want to stay through the storm. However, in general, less than 1 percent of the population refused to evacuate. Cooperation from evacuees was cited as contributing to safe, efficient, and effective evacuations. Public awareness of the hazard, of evacuation procedures, and especially of alerting methods was often cited as contributing to the efficiency and effectiveness of an evacuation.

Katrina evacuation

“The initial evacuation of New Orleans was actually very successful [as Hurricane Katrina approached],” says Lori. “Approximately 80 percent of the population evacuated the city and many tens of thousands more were able to reach the designated shelters. Unfortunately, the shelters were ill-prepared for the sheer volume of evacuees.”

Joe says an important lesson from Katrina should be that emergency management does not end with the evacuation.

“Tens of thousands of individuals were successfully evacuated from their homes to the Superdome and Convention Center,” he says. “The movement of individuals to these shelters was successful, but there were obvious breakdowns in the planning and management for the safety and well being of the public once they reached the shelters.”