Empirical Study of Pedestrians’ Characteristics at Bottlenecks

Summary

The design procedures of Nelson and Mowrer in the SFPE Handbook of Fire Protection Engineering (Society of Fire Protection Engineers, Bethesda, MD, 2002) and Predtetchenskii and Milinskii (PM) in Planning for Foot Traffic Flow in Buildings (Amerind, New Dehli, 1969) are frequently used for capacity analysis of pedestrian facilities, e.g. egress routes. Both agree that congestion occurs in front of a bottleneck, if the incoming flow exceeds the capacity. However, in case of a present congestion in front of a bottleneck, their approaches differ considerably. Nelson assumes that in this case the flow inside a bottleneck is determined by the bottleneck capacity. PM instead expect that the density in front of the entrance to the bottleneck is significant higher than the density, which is attributed to the capacity, and thus the flow inside is lower than the capacity. Furthermore PM assume that the density inside is generally significant lower than the density in front of the bottleneck.

To resolve these discrepancies we studied the pedestrian flow through a bottleneck (Rupprecht, Diploma thesis, University of Wuppertal, 2006) as well as the density and the jam occurrence in front of a bottleneck (Winkens, Diploma thesis, University of Wuppertal, 2007) by an experiment performed under laboratory conditions. The aim was to get reliable data concerning the density directly in front of and inside the bottleneck and thereby to check the assumptions of Nelson and Mowrer and Predtetchenskii and Milinskii.

We found that during the stationary state the density in front of the bottleneck does not depend on the bottleneck width b for 0.8 m≤b≤1.2 m. In conformance with PM the density inside is significantly lower than in front of the bottleneck. In reference to the continuity equation these results cast doubts on the assumption of Nelson that the flow through a bottleneck maintains the value of the capacity if a congestion appears in front of the bottleneck.