...by making it seem less safe.
Riding in his green Saab, we glide into Drachten, a 17th-century village that has grown into a bustling town of more than 40,000. We pass by the performing arts center, and suddenly, there it is: the Intersection. It's the confluence of two busy two-lane roads that handle 20,000 cars a day, plus thousands of bicyclists and pedestrians. Several years ago, Monderman ripped out all the traditional instruments used by traffic engineers to influence driver behavior - traffic lights, road markings, and some pedestrian crossings - and in their place created a roundabout, or traffic circle. The circle is remarkable for what it doesn't contain: signs or signals telling drivers how fast to go, who has the right-of-way, or how to behave. There are no lane markers or curbs separating street and sidewalk, so it's unclear exactly where the car zone ends and the pedestrian zone begins. To an approaching driver, the intersection is utterly ambiguous - and that's the point.
Monderman and I stand in silence by the side of the road a few minutes, watching the stream of motorists, cyclists, and pedestrians make their way through the circle, a giant concrete mixing bowl of transport. Somehow it all works. The drivers slow to gauge the intentions of crossing bicyclists and walkers. Negotiations over right-of-way are made through fleeting eye contact. Remarkably, traffic moves smoothly around the circle with hardly a brake screeching, horn honking, or obscene gesture. "I love it!" Monderman says at last. "Pedestrians and cyclists used to avoid this place, but now, as you see, the cars look out for the cyclists, the cyclists look out for the pedestrians, and everyone looks out for each other. You can't expect traffic signs and street markings to encourage that sort of behavior. You have to build it into the design of the road."
See also this post
from way back. Social psychology is fun. Too bad our society is too stupid to ever take advantage of it.