When disaster strikes, selfless heroism may not be good

Putting others first can cost lives in life-and-death disaster situations involving groups of people, a new study suggested.

The University of Waterloo research, which used computer modelling of a flooded subway station, found overall survival rates were substantially higher when strong people in a 30-member group reached safety themselves before trying to help weaker people.

"Foolhardiness is not a good strategy for rescuing," said lead researcher Eishiro Higo. "In very critical situations, we have to be kind of selfish, but we can still help others if we have proper equipment and proper strategies."

In effect, he said, the study showed that when strong members try to help weak members before they are secure themselves, both are dragged down and the group as a whole suffers.

Higo and colleagues built a two-dimensional computer model of an actual three-level underground space in Kyoto, Japan that consists of a subway platform, a parking garage and a shopping mall.

The model simulates severe flooding from a nearby river, with a mix of adults and senior citizens who must reach safety via staircases from the subway platform level to the surface.

Higo repeatedly ran the model using three different evacuation strategies: one in which people only worried about themselves; one in which people immediately worked together as a group; and one in which those capable of saving themselves reached a safe place before trying to save others using a rope.

In most life-and-death scenarios when variables such as the ratio of adults to seniors were adjusted, the rope strategy resulted in the highest overall survival rate.

In a typical scenario that assumed evacuation efforts beginning at a particular point in time, for example, 12 of 30 people survived using the rope strategy, while there were just five survivors using either of the other two strategies.

"We have to identify what is brave and what is reckless," said Higo. "Helping people from a safe location is still good behaviour and the result is actually much better."

Higo hopes his findings stimulate discussion and lead to the inclusion of relatively inexpensive disaster preparedness features such as ropes and resting areas in public spaces.

The study is published in the journal Expert Systems with Applications.