The aim of the work is to observe the impacts of structural-spatial conditions on the behaviour of children and adolescents by means of comparing a large urban park and an inner-city quarter, and to quantify how much space or autonomous mobility, respectively, is necessary to satisfy needs of children in the city, such as those for motion, social contacts, acceptance and autonomy. The survey areas Donaupark and Karmeliterviertel in Vienna were chosen to carry out hidden unobtrusive observations and face-to-face interviews on site.

The crucial factor for the satisfaction of needs of children in their leisure time is the closeness of the play site to the apartment. It influences the frequency of visits to the play sites, the type of company and therewith the duration of stays as well as the modal choice.

As far as hours per year are concerned, children in the inner-city quarter stay in public space more frequently, as the distances to the Karmeliterviertel are clearly shorter than those to the Donaupark. In both areas, children who are on their way without the company of adults stay outside for longer periods. Due to the closeness of the play sites in the inner-city quarter, most children come on foot, while the Donaupark is mainly reached by car or by public transport. In both areas, unaccompanied children rather use bicycles, scooters, skateboards and roller skates than walking or using public transport.

The importance of playing in an inner-city environment is reflected by the number of social contacts with other children. In Karmeliterviertel, the larger number of children is not accompanied by adults and mainly plays with other children, as normally there are always the same children on the same sites, while in Donaupark children are very much tied to adults.

In both areas, the activity space, defined as the distance children are allowed to move away from adults, rises exponentially with the age. Girls have a smaller action radius than boys. Unaccompanied children have a larger activity space than children in company of adults. Depending on the type of company, the action radius in the Donaupark is larger than in the inner-city quarter. Children who arrive by car have less activity space than children who travel by public transport, by bicycle or on foot.

It has been analysed which streets children use within their activity radius in the inner-city quarter. On car-free places, the activities of children adjust to the size of the space, in all other categories, the action radius rises with age. The analysis also showed that small lanes are still barriers for children up to eight years, as some are not allowed to cross them on their own.

In both areas, mainly active games, rule games and exploration games are of importance; in addition, communication games are often played in the inner-city quarter. Except for the latter group of games, children in Donaupark use more space for their activities than those in Karmeliterviertel. The structure of the play site, including size, location, accessibility, diversity and equipment, influences the type of company of children and therewith their opportunities to acquire space for various games. Children who play with or close to adults use less space than children who are in the area autonomously.

Consequently, the space required for various games presumes a safe network of lanes and sufficiently large places. For the leisure mobility of children and their activity space the closeness to the play site is crucial. It influences the frequency and duration of stay, the type of company and the modal choice.