480 mONE CONTINUOUS LANE

Traffic Waves

Traffic Waves

One small brake.
A ripple of red.

No junctions. No roadworks. Just cars following cars. See how a little hesitation becomes a travelling jam.

The experiment

Traffic on the road

Changing traffic restarts with even spacing.

The gold-ringed car brakes for 1.5 seconds, then drives normally again.

Traffic is flowing evenly. Add a small disturbance.

01 / WATCH

Cars go forwards.
The jam goes backwards.

Each driver slows for the car ahead. Watch the red cluster pass from one car to the next, against the flow.

Try Light traffic: with more space, the same disturbance fades away.

A simplified car-following experiment on a 480 m loop. Colours show speed; red rear lights show braking.

Traffic readings

The circular road0.0 s

Average speed: 29 km/h
Slow cars (< ½ cruise): 0 / 32
Brake events: 0

The wave, unwrapped

Last 120 simulated seconds

Each trace is a car. A red band slanting left shows a slowdown travelling backwards.

Time ↓

0 m · start of loopCars travel →480 m · back to start

body > main { display: none; }.simulation-fallback { max-width: 720px; margin: auto; padding: 24px; line-height: 1.6; }.simulation-fallback img { width: 100%; height: auto; }← Explore all worlds

Traffic Waves

Cars circulate smoothly until one small brake sends a traffic jam travelling backwards. Add more space and see what changes.

Small cars travelling around a circular road with a pale open centre.

Enable JavaScript in a browser with WebGL 2 to run this interactive simulation.

A traffic jam can appear even when there is no obstacle. Sometimes all it takes is one driver slowing down.

Cars move around one circular road. Each driver adjusts their speed to the gap and the car ahead.
Brake one car briefly slows the gold-ringed car. Following drivers brake in turn, and the slowdown can grow into a jam.
Green cars are near their starting speed. Yellow and red cars are slower. Cars keep going forwards while the jam can travel backwards.
The chart unwraps the road from left to right, with time running downwards. The same car reappears at the left when it passes the end of the loop.

Try this: Brake once in Busy traffic and watch at 3× for about half a minute. Then choose Light and brake again. Does the extra space help the disturbance fade?