Traffic waves

Identical drivers on a ring road. Each one copies the car in front, a moment late. Tap the brakes once and watch what happens behind.

← all systems
stopped
desired speed · red tail = brake lights · white = your car (click a car to pick it)

Space-time diagram

position on the ring → (cars drive this way)newest at the bottom ↓

Each row is a snapshot of the whole ring; time runs downwards. A car's path is a line slanting right. A braking wave is a red stripe slanting left: it travels backwards while every car drives forwards.