The experiment is not unique. Tom Vanderbilt wrote an excellent piece in The Wilson Quarterly a few years ago on traffic revolutionary Hans Monderman (see also this NYTimes piece) who has redesigned a number of city centers:

At the town center, in a crowded four-way intersection called the Laweiplein, Monderman removed not only the traffic lights but virtually every other traffic control. Instead of a space cluttered with poles, lights, “traffic islands,” and restrictive arrows, Monderman installed a radical kind of roundabout (a “squareabout,” in his words, because it really seemed more a town square than a traditional roundabout), marked only by a raised circle of grass in the middle, several fountains, and some very discreet indicators of the direction of traffic, which were required by law.

As I watched the intricate social ballet that occurred as cars and bikes slowed to enter the circle (pedestrians were meant to cross at crosswalks placed a bit before the intersection), Monderman performed a favorite trick. He walked, backward and with eyes closed, into the Laweiplein. The traffic made its way around him. No one honked, he wasn’t struck. Instead of a binary, mechanistic process—stop, go—the movement of traffic and pedestrians in the circle felt human and organic.

A year after the change, the results of this “extreme makeover” were striking: Not only had congestion decreased in the intersection—buses spent less time waiting to get through, for example—but there were half as many accidents, even though total car traffic was up by a third.

Alex Tabbarok comments that, while interesting in their own right, these experiments are also very good illustrations of spontaneous order: how order is possible without orders.