Evaluation of Saturation Condition of Signalized Midblock Crosswalks under Mixed Traffic Conditions

Abstract: Pedestrians are subjected to higher pedestrian-vehicle interaction and are most vulnerable to road crashes while crossing a road. Mid-block crosswalks have been reported to be the most hazardous ones among all types of crossing locations. The absence of appropriate crossing facilities for pedestrians at mid-block crossing locations further adds to their vulnerability. In India, Indian Road Congress code i.e, IRC: 103-2022 titled “Guidelines for Pedestrian Crossing Facilities in India” is the formal document which reports the guiding criteria on pedestrian crossing warrants (PCW). It was first published in 1988 and revised in 2012 and 2022. The warrants for the installation of Grade Separated Pedestrian Crossing Facilities (GSPCF) were based on the PV2 (P = Maximum hourly pedestrian flow; V = Maximum hourly vehicle flow) criteria and other microscopic parameters like pedestrian delay and psychological gap size which were calculated at the uncontrolled midblock crosswalks. The IRC:103 doesn’t consider the traffic signal characteristics and saturation condition of signalized midblock crosswalks (SMC) in defining the warrants for GSPCF. Considering these limitations, the current study aims to define the saturated condition of SMC based on pedestrian and vehicle delay. Initially LOS of SMC was defined based on the pedestrian and vehicle delay using k means clustering analysis. The optimal k value was identified based on the elbow and silhouette index method. The pedestrian LOS thresholds were defined from 33 seconds to 70 seconds whereas vehicle LOS were defined from 15 seconds to 32 seconds. Following the development of LOS criteria, multi objective optimization of pedestrian and vehicle delay was carried out using Depth-First-Search algorithm. The objective of the optimization is to identify the pareto optimal solution for pedestrian and vehicle delay for the given traffic signal and traffic flow conditions. A pedestrian delay of 48.081 seconds and a vehicle delay of 25.525 seconds were found to be optimized solution at the existing study areas. The results of LOS criteria and optimal delay values were further used in defining the saturated condition of SMC and the development of pedestrian crossing warrant chart. The current study also suggested a methodology to redesign the traffic signal in such a way that pedestrians and drivers do not encounter a delay beyond the threshold delay values. The proposed PCW chart in the current study can be a useful tool for traffic engineers and urban planners to evaluate the performance of SMC based on vehicle and pedestrian delay. It also aids further in improving safety at SMC by redesigning the traffic signal to minimize the delays of pedestrians and vehicles.