PPolySim OS

Traffic Flow

Why does traffic jam for no reason? Watch phantom jams appear and travel backward through a stream of cars — caused by nothing but random braking.

Traffic Flow StudioLive

Controls

A ring road of cars. Random braking alone creates phantom traffic jams that travel backward — no accident needed.

Presets

▶ Run in Python

Data Inspector

Cells160
Avg speed0.00
Density0.30
ModelNagel–Schreckenberg

Governing equation

Reading this result: Above critical density: stop-and-go waves dominate. Average speed drops sharply — this is the falling branch of the fundamental diagram.

Runs locally in your browser — free forever. Scale to the cloud when reality gets heavy.

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How it works

The Nagel–Schreckenberg cellular-automaton model gives each car simple rules: accelerate, brake to avoid the car ahead, randomly dab the brakes, then move. The space-time diagram reveals jams as backward-traveling waves — the emergent congestion real highways show.

Ask the AI about this model

The math, the assumptions, real-world uses, or a code translation — explained for this exact simulation.

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Frequently asked questions

Is this traffic flow simulation tool really free?
Yes. Traffic Flow runs entirely in your browser using your device's own compute, so local use is free forever. You only pay Compute Tokens if you scale a job to the cloud.
Do I need to install anything?
No. Everything runs client-side in a modern browser — no downloads, no license, no account required to start.
Can I save or share my simulation?
Create a free account to save projects, and use a shareable embed or minted DOI to publish a live, interactive version anywhere.
How accurate are the results?
The solver uses established numerical methods, but results are for research and educational purposes and should be validated against experiment or professional review before you rely on them.