Development and Implementation of Conflict-Based Assessment of Pedestrian Safety to Evaluate Accessibility of Complex Intersections

Abstract

This paper develops and implements the Conflict-based Assessment of Pedestrian Safety (CAPS) methodology for evaluating pedestrian accessibility at complex intersections. In past years, a significant research has been done on pedestrian access to modern roundabouts and other complex intersection forms, including a significant focus on the accessibility for pedestrians who are blind. A majority of these studies have relied on actual street crossings by study participants under supervision of trained Orientation and Mobility (O&M) Specialist. These crossing studies were used to evaluate risk from a measurement of intervention events, where the O&M specialist had to physically stop the participant from crossing. While providing arguably the most accurate data for the crossing risk at a particular intersection, actual street crossings can be dangerous to the study participants, and are further very time consuming and expensive to conduct. The CAPS method presented in this paper emphasizes the use of conflict-based safety factors to quantify risk. The CAPS method relates pedestrian crossing decisions to advanced measurements of vehicle dynamics to estimate lane-by-lane conflicts. CAPS identifies the grade of conflict based on a score generated on a five-criterion rating scale. Each of these criteria or factors has different severity levels, and when combined, provides an overall risk rating of the crossing decision. The CAPS framework was applied to a study of blind pedestrian crossings at a multi-lane roundabout. The resulting risk scores were calibrated from actual O&M interventions observed during the study to give confidence in the CAPS performance. The calibrated CAPS framework correctly matched all (high risk) O&M intervention events, and further identifies other (lower risk) pedestrian-vehicle conflicts. The resulting method has the potential to allow for a faster and most importantly safer evaluation of complex intersections for pedestrian access. Since all factors are measured prior to the pedestrian stepping into the roadway, this approach is compatible with crossing indicator studies, where the participants merely indicate when they would cross, rather than actually stepping into the roadway. The CAPS framework therefore allows for a more objective and consistent safety assessment of pedestrian crossings in a research context without having pedestrians physically step into the roadway.

Developing evasive action‐based indicators for identifying pedestrian conflicts in less organized traffic environments

“…Salamati et al . investigated pedestrian evasive actions in terms of gait changes for pedestrian–vehicle conflicts . In contrast with the proposed research, they used qualitative observational scores in terms of the deceleration magnitude to describe gait evasive action changes.…”

Analysis of Pedestrian–Vehicle Traffic Conflicts in Street Designs with Elements of Shared Space

“…This section, therefore, performs a step-by-step assessment of the PVCA method and makes the necessary additions and amendments in order to refine the methodology and prepare it for application in shared space. It should be noted that a complete description of the original PVCA and CAPS methods can be found in (12,31) and is therefore omitted here; instead, the focus is on the modifications to the issues identified.…”

“…These include: (24), where a method categorising vehicle-pedestrian conflicts at crossings into one of 13 types was derived with a view of identifying potential safety hazards; (25), where pedestrianvehicle conflicts along with traffic characteristics data were used to perform automated assessment of the safety of Pelican crossings in the UK; and (26)(27), in which an automated video analysis system to classify road users as vehicles or pedestrians, identify conflict situations between them and categorise them according to their severity was developed. Also, there are several instances of methods adapted from well-established vehicle-vehicle methods to monitor pedestrian-vehicle conflicts, such as: the application of the STCT in (28) and (29); the use of the USDoTCT in (30); and the adaptation of the CIHTCT in (12) and in (31).…”

Behavioural analysis of interactions between pedestrians and vehicles in street designs with elements of shared space

“…A wide range of traffic conflicts techniques have been developed, many of which are based on well-established vehicle-vehicle methods and adapted so as to account for pedestrian movement. Notable examples include: the ''Swedish Traffic Conflicts Technique'' (STCT) from Lund University in Sweden (Hydén, 1987), applied by Svensson (1998) and Chen, Meng, and Wang (2009) to vehicle-pedestrian conflicts; the ''US Department of Transportation Conflict Technique'' (USDTCT) from the Federal Highway Administration in the US (Parker & Zegeer, 1989), used by Lord (1996) in a vehicle-pedestrian conflicts context; and the ''Institute of Highways and Transportation Conflicts Technique'' (IHTCT) from the Transport and Road Research Laboratory in the UK (Swain, 1987), adapted by Kaparias et al (2010Kaparias et al ( , 2013 and by Salamati et al (2011) to consider the movement of pedestrians. Further techniques have also been developed for the purposes of their respective studies: Cynecki (1980) derived a method categorising vehicle-pedestrian conflicts at crossings into one of 13 types with a view of identifying potential safety hazards; Malkhamah, Tight, and Montgomery (2005) used vehicle-pedestrian conflicts along with traffic characteristics data to perform automated assessment of the safety of Pelican crossings in the UK; and Saunier.…”