Development of Pedestrian Crossing Warrants for Grade-Separated Pedestrian Crossing Facilities under Mixed Traffic Conditions

Abstract

Pedestrian crossing warrants are used to determine when a crossing facility is required and which facility is appropriate for a particular road environment. Existing warrants commonly rely on pedestrian and vehicle volumes, road width, speed and PV² criteria, while the conditions at signalized midblock crosswalks (SMCs) are not always represented adequately. This study examined the conditions under which an SMC operating under heterogeneous traffic should be considered for upgrading to a grade-separated pedestrian crossing facility (GSPCF). Field observations were undertaken at eight SMCs and user-perception surveys were conducted at nine GSPCF locations. Video recordings were used to extract pedestrian and vehicle flow characteristics, queue lengths, crossing times and delays. Pedestrian delay modelling accounted for non-uniform arrivals, signal non-compliance and bidirectional pedestrian interactions; vehicle delay modelling considered mixed traffic and pedestrian influence. The proposed delay models were validated against field observations and the study reported estimation errors below 10%. Delay-based level-of-service (LOS) thresholds were developed using clustering and checked through support vector machine classification and user-perception ratings. The acceptable delays were 45 s for pedestrians and 25 s for drivers. Multi-objective optimization produced corresponding values of 48 s and 25 s, supporting LOS C as the pedestrian saturation threshold and LOS D as the vehicle saturation threshold. The GSPCF preference hierarchy identified by the survey was foot over bridge, hump subway and subway. The findings provide a delay-oriented basis for reviewing SMC performance and considering grade separation, subject to local validation and engineering feasibility.