An interactive explainer

Google Maps has never counted a car.

The road on your screen is red. Nothing on it has been counted. The map is built from phones that share their location. Each one sends a position and a time, a few seconds apart. The colour is one division: how fast those phones are going, divided by how fast that road normally goes. Watch that number get built from two pings. Then find out why the red road carries fewer cars per hour than the orange one.

Google Maps traffic · GPS probe data · Map matching · Free-flow speed

Systems · Intermediate · 11 min · Why a road turns red without anyone counting a car — an interactive explainer on ViLearn, with a simulation and a knowledge check. All explainers.

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