Many European cities implement shared spaces or other mixed traffic concepts in order to revitalize city centers and provide alternatives to car-centric road designs. The main idea is to treat all modes of traffic equally and encourage social interaction between road users with the prospect of cooperation over egoism. Furthermore a higher attractiveness of a road for people requires a careful traffic behavior, increased safety and lower speeds and a more attractive urban environment overall. Little research has been done how and if the new road design can also help pedestrians and bicyclists to reclaim previously car-dominated spaces.

The analyses of existing implementations can support planners by objectively showing the effect on traffic behavior. In this paper the traffic situation at the Sonnenfelsplatz in Graz (Austria) is compared before and after it has been redesigned from a complex roundabout to a shared space. The traffic flow in the investigated area is about 1.000 motorized vehicles, up to 600 bicyclists and 3.000 pedestrians in the peak hour (before reconstruction). This location has been chosen because of the diversity of traffic modes and the high traffic volume in general. Therefore, the trajectories of pedestrians, bicyclists and cars have been recorded and analyzed. Among the compared characteristics are: The spatial distribution of road users, the consistency in speed and travel times, length of paths as well as safety aspects.