This thesis questions the walk in urban context, its practice, performances, walking behaviours and strategies used by walkers when walking, in more or less comfortable situations / uncomfortable, but also how urban policies apprehend this object.This research interests in the daily practice of walk in a dense urban context, usefulness, trivial walking and sometimes denied because automated.This research captures the pedestrian urban mobility by presenting the results of two main areas, namely:- The "In situ" to understand the "how" of walking in cities, in other words the walkers behaviours depending on more or less comfortable situations- The "Ex situ" to identify the "why" of walking and what walkers say about this object. It was about to study the representations of pedestrian urban mobilities.Is the environment (social, temporal and physical) determining the walker behaviour? In which measure(s) the evaluation of the comfort level of a driving situation is involved in the establishment of pedestrian movement strategies?Are the walking social representations involved in choosing to walk in cities?We will also see in which measures walking and pedestrian users have become issues for urban public policies and particularly in the Parisian context (City of Paris). The aim will be to put into perspective this research, in regards with the political context in which it is registered