The effects of upstream guardrail layouts on regulating pedestrian merging flow

Pedestrian merging flow in public areas may create disorder as a potential bottleneck raising fatal crowd accidents. However, research on understanding pedestrian merging behaviors to improve the performance of existing merging scenarios is limited. In this study, controlled experiments were conducted to explore pedestrian interactions of merging flow and regulatory effects of upstream guardrails (guardrails set before merging). Key variables considered include the spacing between guardrails, the distance of guardrails to the merging area, and the desired velocity of pedestrians. Findings reveal that properly setting up guardrails facilitates stable lane formation, optimizes space utilization, and improves merging efficiency. The maximum increase in merging velocity and outflow is 17.3 % and 15.2 % respectively. However, excessive guardrails might increase merging pressure in terms of higher local density. The effectiveness of guardrails is sensitive to the distance to the merging area, and some observed special self-organization phenomena like zipper effect, lane avoidance, and lane fusion, also greatly affect the effectiveness of guardrails. The modified Simpson Diversity Index quantifies the disorder level and shows that the lane status before merging is important to promote the formation of orderly paths during the merging process, thus ensuring merging performance. Besides, setting up guardrails at higher desired velocity is notably effective in alleviating density. Above findings highlight the importance of balancing the efficiency with crowding status in the merging area by reasonably regulating the upstream inflows. The results propose an in-depth understanding of pedestrian dynamics in merging flow and valuable insights for improving crowd safety management strategies in public spaces. © 2025 Elsevier Ltd