Pedestrian lane formation and its influence on egress efficiency in the presence of an obstacle

Due to the inevitability of placing obstacles when designing walking facilities, it is important to understand the influence of the obstacle during pedestrian egress to build a safer and more efficient walking environment. However, previous experimental studies on the influence of the obstacle during egress tend to be controversial: some suggest improving egress efficiency, whereas others do not. This controversy is probably due to the diversified obstacle layouts and pedestrian pushing degree, making the influencing mechanism of the obstacle layout alone dubious. In this paper, we focus on the obstacle layout and explore its influencing mechanism on pedestrian egress efficiency under conditions without intentional physical pushing. Controlled experiments were conducted under various obstacle layouts in terms of obstacle size and obstacle-exit distance. The preliminary analysis revealed that the obstacle layout affected egress efficiency, which we hypothesized was due to the pedestrian lane formation, i.e., the single-files of self-organized pedestrians directed toward the exit. For a quantitative validation, we proposed a novel two-layer k-means clustering method to recognize the pedestrian lanes that are nearly parallel. Accordingly, the deviation parameter, which represented the deviation of pedestrians from the established lane, was proposed to evaluate the lane-formation status. We also found a positive correlation between the deviation parameter and the egress time, suggesting that worse lane-formation status could lead to lower egress efficiency. Moreover, the deterioration of the lane-formation status was mainly caused by the lane-changing behavior, which indicated pedestrian movements from one lane to another. Further analysis showed that the lane-changing behavior was presumably motivated by the tendency of pedestrians to pursue better egress direction before the exit. Results indicated that the obstacle can be used to adjust the pedestrian lane-formation status, thus controlling the egress efficiency. We would also suggest the possibility of stabilizing the egress efficiency through restraining the pedestrian lane-changing behavior. We expect this paper to contribute to the reasonable placement of obstacles in actual walking facilities with diversified obstacle layouts and pedestrian characteristics.