A Decision-based Criterion for Selecting Parameters in the Evaluation of Pedestrian Safety Problems with the Traffic Conflict Analysis Technique

This article discusses and applies methods for developing diagnostic parameters for pedestrian traffic safety problems using the traffic conflict analysis technique (TCT) to a study of pedestrian crossings at urban signalized intersections in São Paulo, Brazil. The development of parameters has two tasks: the selection of an adequate classification of conflicts and/or segmentation of crossings, and the determination of parameters for the classes (including recommended confidence levels). Based on the US Federal Highway Administration guides for the study of vehicular conflicts, the pedestrian conflict count limits (abnormally high level of counts for problem detection) and the ratio of accidents per million conflicts (risk index and accident forecasting rate) are developed for the types of urban crossings observed in the signalized intersections of the study. Statistical methods are applied with a new decision-based criterion that could select the best classification/segmentation and the recommended confidence level to be used in applied work. Results obtained from the application of such methods to the case study are presented and discussed as an example application.