While urban design and planning focuses strongly on actor-oriented and user - oriented design and planning approaches, technologies that give insight into the behaviour of actors and users are rapidly evolving. Especially the use of tracking technologies - of which GPS is best known - is booming in urban research. Most research focuses on the technological possibilities and problems of using tracking devices. Little attention is paid to the questions to what extend and in which manner knowledge developed through the use of new tracking technologies might influence spatial design and planning decisions (Hoeven, 2008). Aim and Methodology.: Using GPS technology to observe walking patterns in city centres replaces old techniques and offers new abilities collecting a broad scale of data: a tool for evaluation and for discovering new insights. With GPS tracking it is possible to gather individual and collective data on routing, whole trip (including access transportation), access points spent time, visited streets (network), visited locations (activities), intensities of use of space. In the Spatial Metro project GPS racking was used to evaluate the actual impact of investments and also to analyse pedestrian movement in the cities: measuring, valuing and predicting the demand for investment in pedestrian facilities (Van der Spek, 2008). Results and Main conclusion: While collecting data using GPS tracking it is possible to get more insight in pedestrian behaviour and pedestrian movement in cities. It is possible to discover e.g. neglected places, qualitative places, gaps in the pedestrian network and main pedestrian routes. This insight should offer new abilities for Pedestrian Oriented Design for the city. Tracking Delft: In this paper the Tracking Delft Pilot will be described. Here, tracking has been used to come to new insights and to define interventions in public space to improve the walkability of the city centre. In November 2009 ten students carried out research in the city centre of Delft: from two parking garages pedestrians were tracked and interviewed during four days. The research consisted of three parts: 1. General evaluation of the tracks ie by layering and making sub groups based trip or personal characteristics; leading to Design Interventions based on the routing and destinations of individuals as well as on collective behaviour. 2. Evaluation of the experience of pedestrians (Preferences research by Ohyoon Kwon) 3. Evaluation of space based on the methodology of Gehl (by Tine van Langelaar) The research lead to two other papers: Tracking Delft from the perspective of preferences of people (Kwon) and comparison of use and influence of design based on behaviour of inhabitants and visitors (Van Langelaar). This paper will focus on the design interventions based on the actual pattern of use of visitors.