distinguish from the more common "low car development") is based mainly on experience in Northwestern Europe, where the movement for car-free development began. Within this definition three types are identified: Vauban model Limited Access model Pedestrian zones with residential population Vauban Vauban, Freiburg, Germany is according to this definition, the largest car-free development in Europe, with over 5,000 residents. Whether it can be considered car-free is open to debate: many local people prefer the term "stellplatzfrei" – literally "free from parking spaces" to describe the traffic management system there. Vehicles are allowed down the residential streets at walking pace to pick up and deliver but not to park, although there are frequent infractions. Residents of the stellplatzfrei areas must sign an annual declaration stating whether they own a car or not. Car owners must purchase a place in one of the multi-storey car parks on the periphery, run by a council-owned company. The cost of these spaces – €17,500 in 2006, plus a monthly fee – acts as a disincentive to car ownership. Limited access type The more common form of car free development involves some sort of physical barrier, which prevents motor vehicles from penetrating into a car-free center. Melia et al. describe this as the "Limited Access" type. In some cases such as Stellwerk 60 in Cologne, there is a removable barrier, controlled by a residents' organizations. In others cases, such as in Waterwijk, vehicular access is only available from the exterior. Pedestrian zones Whereas the first two models apply to newly built car free developments, most pedestrianized areas have been retro-fitted. Pedestrian zones may be considered car-free developments where they include a significant population and a low rate of vehicle ownership per household. The largest example in Europe is Groningen, Netherlands which had a city centre population of 16,500 in 2008. Benefits and problems Several studies have been done on European car free developments. The most comprehensive was conducted in 2000 by Jan Scheurer. Other more recent studies have been made of specific car-free areas such as Vienna's Floridsdorf car-free development. The main benefits found for car free developments (summarized in Melia et al. 2010) found in the various studies are: very low levels of car use, resulting in much less traffic on surrounding roads high rates of walking and cycling more independent movement and active play amongst children less land taken for parking and roads –