Simulating Dynamical Features of Escape Panic Dirk Helbing, Illés Farkas, and Tamás Vicsek Alex Turek

Stampedes People trying to move faster than normal Physical interactions between people Uncoordinated passing of bottlenecks Arching/clogging at exits Dangerous pressures within jammed crowd (up to 4,450 N/m) People move or try to move considerably faster than normal. Individuals start pushing, and interactions among people become physical in nature. Moving and, in particular, passing of a bottleneck becomes incoordinated. (iv) At exits, arching and clogging are observed. (v) Jams are building up. (vi) The physical interactions in the jammed crowd add up and cause dangerous pressures up to 4,450 Newtons per meter,2,5 which can bend steel barriers or tear down brick walls. (vii) Escape is further slowed down by fallen or injured people turning into “obstacles”. (viii) People show a tendency of mass behaviour, i.e., to do what other people do. (ix) Alternative exits are often overlooked or not efficiently used in escape situations.

Stampedes (cont’d) Injured/fallen people turn into obstacles Tendency of “mass behavior,” i.e. herd instinct Alternative exits are overlooked or underused People move or try to move considerably faster than normal. Individuals start pushing, and interactions among people become physical in nature. Moving and, in particular, passing of a bottleneck becomes incoordinated. (iv) At exits, arching and clogging are observed. (v) Jams are building up. (vi) The physical interactions in the jammed crowd add up and cause dangerous pressures up to 4,450 Newtons per meter,2,5 which can bend steel barriers or tear down brick walls. (vii) Escape is further slowed down by fallen or injured people turning into “obstacles”. (viii) People show a tendency of mass behaviour, i.e., to do what other people do. (ix) Alternative exits are often overlooked or not efficiently used in escape situations.

Studying Stampedes Mostly social psychology (mentality of herd behavior) Helbing et al. attempted to model them using self-driven particle systems Combine socio-psychological and physical forces

A Single Particle Affected by multiple forces: Desired Velocity and associated acceleration Interaction forces

Desired Velocity Force Helbing et al. specified these parameters: vi0 (Desired velocity) 0.6 m/s – Relaxed 1.0 m/s – Normal 1.5 m/s – Nervous >1.5 m/s – Panic (transition to uncoordinated bottleneck behavior)

Interaction Forces Psychological desire to have room between you and another person Psychological desire to not be too close to the walls F F

Interaction Forces Body force – counteracting body compression Sliding friction force – counteracting movement tangential to something you’re in contact with F F F

Measured Effects: Transition to uncoordination due to clogging Arch-like bunching, with avalanche effect when arches break (demo)

Measured Effects: Faster-is-Slower Effect Attempting to have too high a vi0 High interpersonal friction becoming the dominant force at a bottleneck Buildup of forces causing extremely high pressures, and injuries (demo) Asymmetrical columns can improve outflow and prevent buildup of fatal pressures (demo)

Measured Effects: Faster-is-Slower Effect Jamming can occur at widening of escape routes (demo)

Measured Effects: Mass Behavior Individualism vs. Herd behavior Each pedestrian may either select individual direction, follow avg. direction of his neighbors in a certain radius, or a mixture of both, weighted by panic parameter pi. (demo) Desired direction at time t

Measured Effects: Mass Behavior Both have drawbacks: All individualistic means no one will learn from anyone else (demo) All herding means no exploration for other exits (demo)

Leaving time vs. Desired velocity Measured Data Leaving time vs. Desired velocity

Measured Data Leaving time for 80 people, given different combinations of individualistic and herding behavior

Questions? Cited Paper: Helbing, Farkas, Vicsek. “Simulating Dynamical Features of Escape Panic”. 2000 http://www.eecs.ucf.edu/~lboloni/Teaching/EEL6938_2007/papers/Helbing-EscapePanic.pdf Presentation by Alex Turek