Occupant egress simulations that impact codes fall short, researchers say

Simulations of mass evacuations of buildings are inadequate, according to two European researchers, and resulting designs put occupants at risk.

Modern safety engineering aims to make it so occupants can exit a structure during a fire or other disaster before it collapses. But variables complicate egress simulations that influence codes and designs. “It depends on the building and the escape routes, but crucially also on how people behave,” the researchers write.

“The problem is that the simulations aren't good enough – that's what we have learned from detailed behavioral studies based on recent fires and terrorist attacks including 9/11 and the Mont Blanc tunnel fire of 1999 in which 41 people died,” they say.

Evacuees decide whether and when to start moving, in which direction, whether to respond to other evacuees, and which exit to use. “Each choice also depends on how various factors interact with one another. Is the decision maker bold or risk-averse? Is there smoke in the room? How far away are the exits? And of most interest for our research purposes, what are the other evacuees doing?”

“Herding” behavior, when large groups follow the crowd, is typically discouraged in designs; but safer alternatives may derive from understanding and possibly exploiting this tendency.