A Social Force Model simulation where agents navigate toward exits while avoiding collisions. Toggle panic mode to observe clogging at narrow doors — the counter-intuitive 'faster-is-slower' effect.
Dirk Helbing's Social Force Model treats each pedestrian as a particle subject to three forces: a desired-velocity force toward the exit, repulsive forces from other pedestrians, and repulsive forces from walls. In panic, desired speed increases but clogging decreases overall flow.
Watch agents stream toward the exit in normal mode. Toggle panic — desired speed doubles but arch-shaped clogs form at the door, reducing throughput. Add a column obstacle near the exit to see how it paradoxically improves flow.
Adding a pillar in front of a narrow exit counter-intuitively improves evacuation flow by breaking the arch-shaped clog. This finding by Helbing et al. (2000) has influenced building codes worldwide.