A cellular automaton simulating city traffic. Red cars only move right; Blue cars only move down. They take turns moving. A car can only move if the space in front of it is empty.
This model is famous for its sharp phase transitions. Below a critical density (around ~35%), traffic perfectly self-organizes into diagonal free-flowing bands. Above the critical density, a single macroscopic traffic jam suddenly forms, freezing the entire city.
Use the slider to change the density and see how the system collapses from order into chaos.