Capacity estimation is an important tool for the design and dimensioning of pedestrian facilities. The literature contains different procedures and specifications that show considerable differences with respect to the estimated flow values. Moreover, new experimental data indicate a stepwise growth of capacity with width and thus challenge the validity of the specific flow concept. To resolve these differences, we experimentally studied the unidirectional pedestrian flow through bottlenecks under laboratory conditions. The time development of quantities such as individual velocities, density, and individual time gaps in bottlenecks of different widths is presented. The data show a linear growth of flow with width. The comparison of the results with experimental data from other authors indicates that the basic assumption of the capacity estimation for bottlenecks has to be revised. In contrast to most planning guidelines, our main result is that a jam occurs even if the incoming flow does not overstep the capacity defined by the maximum flow according to the fundamental diagram.

A series of well-controlled laboratory experiments with up to 350 test persons were performed to investigate the pedestrian flow through wide bottlenecks. The density and velocity inside the bottleneck do not depend on the bottleneck width, while those in front of the bottleneck change with the width. A linear dependency is found between the flow and bottleneck width (up to 5 m) by comparing our results with the data from literature. However, differences appear only if the data from steady states are used. These differences indicate the effects of other factors like bottleneck length et al. on the flow