A pedestrian merging flow model for stair evacuation

Pedestrian merging flows on stairs are defined as the confluence of a flow of pedestrians from a stair and pedestrians from each floor of a multi-storey building. This paper introduces a novel simplified mathematical model for the calculation of evacuation times on stairs which takes into account the impact of merging flows. The model allows calculating the impact of merging ratio (people accessing the stair landing from the floor and from the stair) on pedestrian flows and evacuation times at each floor in congested situations. The assumptions and implementation of the model are presented. A hypothetical model case study of a 10-floor building evacuation is investigated, where the results of the new model are compared with the results of an evacuation simulation model using SimTread. Advantages and limitations of the new model in relation to the existing methods adopted for the simulation of merging flows on stairs are discussed.