The Complexities Behind Crowd & Pedestrian Movement
04/30/12 11:52AM | Category: Evacuation

Article Quoted from The Economist


Imagine that you are French. You are walking along a busy pavement in Paris and another pedestrian is approaching from the opposite direction. A collision will occur unless you each move out of the other’s way. Which way do you step?

The answer is almost certainly to the right. Replay the same scene in many parts of Asia, however, and you would probably move to the left. It is not obvious why. There is no instruction to head in a specific direction (South Korea, where there is a campaign to get people to walk on the right, is an exception). There is no simple correlation with the side of the road on which people drive: Londoners funnel to the right on pavements, for example.

Instead, says Mehdi Moussaid of the Max Planck Institute in Berlin, this is a behavior brought about by probabilities. If two opposing people guess each other’s intentions correctly, each moving to one side and allowing the other past, then they are likely to choose to move the same way the next time they need to avoid a collision.

Whether stepping aside to avoid a collision, following the person in front through a crowd or navigating busy streets, pedestrians are autonomous yet constrained by others. They are both highly mobile and very predictable. “These are particles with a will,” says Dirk Helbing of ETH Zurich, a technology-focused university.

Messrs Helbing and Moussaid are at the cutting edge of a youngish field: understanding and modeling how pedestrians behave. Its purpose is not mere curiosity. Understanding pedestrian flows makes crowd events safer: knowing about the propensity of different nationalities to step in different directions could, for instance, matter to organizers of an event such as a football World Cup, where fans from various countries mingle. The odds of collisions go up if they do not share a reflex to move to one side. In a packed crowd, that could slow down lots of people.

This article demonstrates the complexity behind crowd and pedestrian movement, one of the various factors that REGAL tools take into account when determining evacuation times. REGAL’s concerns do not necessarily involve the movement of each individual person as an autonomous entity but rather focuses on the movement of a multitude of people forming subgroups of the total population that move in unison to their final destination.

As an example, Michael Dowling, REGAL’s Sr. Analyst, typically calibrates the simulation model to allow pedestrian mobility where applicable (i.e. sidewalks, concourses, etc.) and limits maneuverability in certain areas (i.e. stairs, seating rows. etc). Additionally the model is also calibrated to reflect observed pedestrian behavior in response to a crowd.  Each individual entity is assigned physical attributes and is provided decision making intelligence to make the determination of whether to maneuver through a crowded area or seek an alternate route. Depending on the circumstances, the simulation can be developed to provide the entities that will to choose their path based on their environmental factors or limit them to a specified and pre-determined route.

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