Assessing the Safety Benefits of In-Vehicle Warning Information by Vehicle Interaction Analysis in C-ITS Environments

The cooperative-intelligent transport systems (C-ITS) shares useful real-time traffic information including upcoming hazards in support of vehicle-to-vehicle (V2V) and vehicle-toinfrastructure (V2I) wireless communications. The safety applications provided in the C-ITS environment allow the driver to respond quickly to unexpected hazardous situations and to prevent accidents. This study aims to quantitatively evaluate the safety benefits of C-ITS when the in-vehicle warning information is provided. A novel feature of this study is to use a multi-agent driving simulation method capable of analyzing vehicle interactions between a subject vehicle and a preceding vehicle in terms of crash risks. The crash potential index (CPI) is adopted to evaluate rear-end crash risks, and various compliance levels of C-ITS drivers are further taken into consideration in the analysis. In case the subject vehicle received the warning information was defined as the “With” scenario, and the case that the subject vehicle did not receive the warning information was defined as the “Without” scenario. In addition, to analyze the impact of providing alert information on traffic safety from compliance rates, it is defined in this study that drivers comply with given warning information in the case where the speed and CPI decrease after the warning message is displayed. And the changes in the probability of accidents caused by the subject’s compliance rate were compared. Results showed that the driving speeds and CPIs of the “With” scenarios were lower compared to the “Without” scenario, and 55.81% of CPI reduction was achievable due to the warning information provision. According to the CPI effectiveness analysis on the compliance rate, the average CPI decreased as the compliance rate increased. When all the drivers complied with the warning information in the C-ITS environment, the crash potential was reduced by 67.86% compared to the case that all drivers did not comply with the warning information. The outcomes of this study are expected to be useful as a fundamental for developing effective policies to fully exploit the benefits of C-ITS applications.