Safety problems in urban cycling mobility: A quantitative risk analysis at urban intersections

Abstract

The attention to the most vulnerable road users has grown rapidly in recent decades.The experience gained reveals an important number of cyclist fatalities due to road crashes; mostof which occur at intersections. In this study, dispersion of trajectories in urban intersections hasbeen considered to identify the whole conflict area and the largest conflict areas between cars andbicycles, and the speeds have been used to calculate exposure time of cyclists and reaction timeavailable to drivers to avoid collision. These data allow the summary approach to the problem,while a risk probability model has been developed to adopt an elementary approach analysis.A quantitative damage model has been proposed to classify each conflict point, and a probabilisticapproach has been defined to consider the traffic volume and the elementary unit of exposure.The combination of damage and probability, permitted to assess the risk of crash, at the examinedintersection. Three types of urban four-arm intersection, with and without bike paths, wereconsidered. For each scheme, the authors assessed the risk of collision between the cyclist andthe vehicle. The obtained results allowed the identification of the most hazardous maneuversand highlighted that geometry and kinematics of traffic movements cannot be overlooked, whendesigning an urban road intersection. The strategy proposed by the authors could have a significantimpact on the risk management of urban intersections. The obtained results and the proposed hazardestimation methodology could be used to design safer intersections.