Delft University of Technology has recently carried out experimental pedestrian flow research to assess the design of walking infrastructure, support planning of timetables for public transit and to identify the tools to aid the designer . The main objective of such an action was to calibrate and validate the microscopic and macroscopic pedestrian flow models. Interesting first results pertain to the way in which the narrow bottleneck is used under saturated flow conditions, and the use of the space (or rather,width) upstream of the bottleneck in case of congestion. For the purpose of investigation the pedestrians were observed using a digital video camera mounted at the ceiling of the building in which the experiments were carried out. The resulting video footage was analyzed using specially designed pedestrian detection and tracking software, yielding detailed microscopic pedestrian data. Having considered the narrow bottleneck situation only, it was found that during near-capacity and capacity flow situations, the bottleneck is used differently than in case of free flow conditions. While at free-flow conditions, pedestrians will walk in the center of the bottleneck, thereby maximizing the distance between themselves and the walls. During capacity conditions, two trails or lanes are formed: pedestrians tend to walk diagonally behind each other, thereby reducing the headways and thus maximizing the use of the infrastructure supply. Another interesting result pertains to the use of the available space in case of congestion. It turns out that only a small amount of the width is used at the location of the bottleneck (namely, the width of the bottleneck itself). Further upstream, the pedestrian stream 'spreads out' covering more or less the entire available width.