A model evacuation

Researchers are using computer modelling to study how to best evacuate the disabled when masses of people are fleeing a building.

“September 11 really brought up some huge concerns,” says Judith Holt. “There were many people in the two towers with disabilities. In past decades we’ve been worked hard so disabled people can get into buildings, but we haven’t dealt much with how to get them out, especially in emergency situations.”

Holt and Keith Christensen, with Utah State University’s Center for Persons with Disabilities, are researching how well accommodations for getting disabled people into buildings work when lots of people are trying to get out.

“In an emergency situation, the pedestrian dynamic changes when 40 or more people are trying to get out of one door at once, said Christensen.” “We are looking at what happens in that type of situation, he said”

One difficulty during building evacuations is that disability-accessible entrances seem like the best route - for everyone. So, in an emergency, many people will choose the most accessible exit, making it unavailable for the people who have no other alternative.

“The main problem with this study is that you can’t practice with people,” says Christensen. “You can’t put 10,000 people in a stadium, declare an emergency, and then watch what happens. Getting large groups out of a building fast can’t be studied in real time with real people.”

Instead of studying actual building evacuations, Holt and Christensen are using computer models to predict how big groups of people will act in an emergency.

The research uses a method called ‘agent-based modelling,’ which creates thousands of individual computer people, or agents, each with their own tendencies and behaviours, such as how fast they move, whether they will follow a crowd or not, how they perceive exits, and their aversion to narrow hallways. Some of these agents are programmed with disabilities, and their exits are watched especially closely.

Accessible evacuation does not affect the 10 percent of the population with diagnosed disabilities, says Holt. “As we get older, we will all end up disabled. It’s a population everyone gets to belong to if they live long enough.”