Midnight Crowd: Pedestrian Wave Dynamics

A top-down, simplified social-force crowd of New Year's Eve pedestrians walks both directions along a closed loop avenue toward midnight. Every agent only ever reacts to its own desired direction and the neighbours and lampposts nearest to it — yet at high density the crowd spontaneously splits into directional lanes and develops backward-travelling stop-and-go density waves, the same emergent physics behind phantom traffic jams. Adjust density, desired speed, repulsion strength/range and the bidirectional flow ratio to see how each one tips the crowd between smooth flow and jamming.