Appleyard compared three physically similar San Francisco residential streets carrying roughly 2,000, 8,000 and 16,000 vehicles a day, and asked residents whom they knew and which space they counted as their own. People on the light street named about three more friends and twice as many acquaintances as those on the heavy street, and drew their personal territory as reaching across the roadway rather than stopping at the kerb. Traffic, on this evidence, does not merely pass through a street; it consumes it as social space. The book set out protection measures - traffic calming, closures, shared surfaces, planting - together with a claim of right: the street belongs to the people who live on it, not to through-traffic.
It supplied the empirical basis for treating the street as public space rather than as a conduit, and became the standard reference for traffic calming, the export of the woonerf, home zones and 20 mph limits. Replications in Bristol, Toronto and Delhi have found the same gradient between traffic volume and social life.
See it on the timeline →