Europe is in the process of quickly catapulting beyond the US when it comes to pedestrianizing urban areas.

While American cities are synchronizing green lights to improve traffic flow and offering apps to help drivers find parking, many European cities are doing the opposite: creating environments openly hostile to cars. The methods vary, but the mission is clear — to make car use expensive and just plain miserable enough to tilt drivers toward more environmentally friendly modes of transportation.

Cities including Vienna to Munich and Copenhagen have closed vast swaths of streets to car traffic. Barcelona and Paris have had car lanes eroded by popular bike-sharing programs. Drivers in London and Stockholm pay hefty congestion charges just for entering the heart of the city. And over the past two years, dozens of German cities have joined a national network of “environmental zones” where only cars with low carbon dioxide emissions may enter.

Is it a matter of courage, intelligence, vision, or some combination that is inspiring this trend? What has to happen to urban planning principles to support the effort?