New Traffic Conflict Measures Using Potential Outcome Models

Abstract

We propose new measures for assessing traffic conflicts, called “Potential Response Inspired Conflict (PRIC)”, taking the counterfactual sentence “there is a risk of collision if their movements remain unchanged” into account, based on the potential outcome models. Such a counterfactual sentence is used in the widely acceptable definition of traffic conflict given by ICSTCT (Amundsen and Hyden, 1977). First, we point out that most of existing traffic risk evaluation measures may not take such a counterfactual sentence into account.To solve this problem, we introduce the potential outcome model into traffic conflict technique, in order to formulate the PRICs. In addition, we provide three identification conditions for the PRICs, and show that the existing traffic risk evaluation measures can statistically reflect the definition of the traffic conflict through the PRICs under certain conditions. Furthermore, when the proposed identification conditions do not hold, we formulate the bounds on the PRICs under certain causal assumptions.Finally, through the application of the PRICs to numerical examples and “The 100-Car Naturalistic Driving Study (Dingus et al., 2006)”, we discuss the usefulness and limitation of the traffic conflict measures.