Pedestrian Flow Characteristics at Upstream and Downstream of Bottleneck for Unidirectional Flow under Normal Conditions

Abstract

The study of pedestrian flow characteristics at upstream and downstream of bottlenecks is important from level of service and evacuation perspective. Many controlled laboratory experiments have been conducted to study pedestrians’ behavior at bottlenecks. However, it is unclear whether experiments can reproduce real crowd flow characteristics. In this paper, real field data was collected at normal conditions for unidirectional pedestrian movement at Mahakaleshwar, a Hindu temple at Ujjain, India during Mahashivaratri, a festival day on which a large number of pilgrims visited the temple. Along the corridor there is a width reduction at a U-turn which creates a bottleneck. It is necessary to study pedestrian flow characteristics at bottlenecks to ensure desired level of service at temple premises during heavy flow. The speed-density relationships of upstream and downstream sections were compared and it was found that flow behavior at both the sections of bottleneck severely differ from each other. Pedestrians in the upstream are either at free flow speed for very low density values or moving slowly for intermediate to high range of density values. From the speed-density relationship, it can be concluded that pedestrians at upstream had visual clues of congestion ahead at bottleneck (pedestrian could also see the downstream flow through barricades). Therefore, pedestrians wait at their position, stay in their comfort zone and do not push each other. Thus, even at intermediate local density, pedestrians have such low speeds. This violates the general assumption that pedestrians change their speed only at the shockwave boundary. The movement of pedestrians at upstream is governed by local density and information of congestion status ahead, whereas pedestrian movement at downstream is governed by factors like density, side friction and pedestrians’ willingness to compensate for the delay at bottleneck. This study is expected to have application in planning and operation of pedestrian facilities.