Since thirty years in France, the accessibility to public urban space became a major challenge for the planning of cities and the improvement of the quality of life of city dwellers. But the approaches continue to be standards approaches and they encourage a proliferation of isolated technical devices for disabled people. This paper suggest to approach the accessibility through the field of the architectural and urban ambiences, from the diversity of the ordinary pedestrian practices. It shows how pedestrian accessibiliy depends on a perceptual and situated achievement. It introduces the idea of "sensory configuration". The pedestrian's configuring activity involves in taking hold of, associating and finally appropriating resources (visual, bright, sound, tactile, thermal… resources) afforded by the sensory environment. This activity enables pedestrians to decode their immediate surroundings, to orient themselves and finally to adjust their behaviour to the urban situations.