Categorical modeling to evaluate road safety at the planning level

Abstract

The most efficient strategy to ensure long-term road network safety is to integrate safety analysis into the planning process of a network or a corridor. Safety planning decision-support tool outcomes should be reliable and realistic, taking into account the main characteristics of this particular level, which is characterized by scant and generalized data. However, the tools developed and presented in previous studies are based on models with a quantitative response. To develop a more suitable tool while maintaining a measure assessment character, this work presents a qualitative response model whose outcome is the risk of occurring three degrees of hazards: low, medium, and high. In this study, an ordered probit model was applied to an urban road network using Porto city data. Hazard categories were defined using accident frequency to reflect a measure of the safety of the road network studied. The developed model provides a safety risk analysis considering road data that are easy to gather or estimate at the planning level. In addition, an analysis of hypothetical scenarios for two sample segments is presented to illustrate an application of the categorical model in typifying an accident risk analysis at a planning level. © 2012 Copyright Taylor and Francis Group, LLC.