Phased evacuation: An optimisation model which takes into account the capacity drop phenomenon in pedestrian flows

Experiments have been performed to study pedestrian flow through bottlenecks under oversaturated conditions. The data underline a new phenomenon in pedestrian flows: when high-density conditions occur upstream of a bottleneck, the maximum capacity of the bottleneck (i.e. the maximum number of pedestrians that can flow through the bottleneck in a given time interval) can drop. This is referred to as “capacity drop” and should be carefully taken into account when dealing with building evacuation philosophy.