The Case for Designing at Human Speed

In 1961, traffic psychologist Karl Peglau was tasked with a deceptively simple problem: make pedestrians in East Berlin stop and look before crossing the street. His solution had no sensors, no algorithms, no app. It was a small man in a hat — arms spread wide to say “wait,” then stepping forward with jaunty confidence to say “go.” The Ampelmännchen was born not from a design sprint but from a single, clear mandate: a child should understand this signal without being told what it means.

A Silhouette That Stops a City

What makes Peglau’s figure remarkable is not its charm, though charm it has. It is the rigour of the simplification. Every element serves function. The hat distinguishes the head from the body at low resolution and in fog. The outstretched arms of the stop figure create a visual barrier — your eye reads “blocked” before your brain processes the colour. The walking man leans forward at exactly the angle that suggests safe, purposeful movement.