ANALYSIS OF VEHICULAR DECELERATION CHARACTERISTICS LEADING TO UNSAFE DRIVING SITUATIONS

Abstract

Transportation safety has been recognized as a public health issue worldwide, consequently, transportation researchers and practitioners have been attempting to provide adequate safety performance for the various transportation components and facilities to all road users given the usually scarce resources available. Safety engineers have been trying to make decisions affecting safety based on the knowledge extracted from different types of statistical models and/or observational before-after analysis. It is generally recognized that this type of factual knowledge is not easily obtained either statistically or empirically. Despite the intuitive link between road safety and observed crashes, a good understanding of the sequence of events prior to the crash can provide a more rational basis for the development of engineering countermeasures. The development of more comprehensive mechanistic models for safety assessment is heavily dependent on detailed vehicle tracking data that is not readily available. In this thesis, a parameter which can measure the level of safety in absolute terms known as Severity Index which is combination of deceleration and Post Encroachment time, proximity measure was proposed. Since Deceleration was used to find the severity of an event using threshold values but these threshold values didn’t reflect level of severity along with its frequency. Deceleration cannot define severity alone therefore Severity Index was proposed which could define probability of collision and can relate to its consequence (Fatal, Injuries and PDO). Further Severity Index was classified into 4 group using clustering analysis which suggest non serious and serious events. While Serious events were divided into Higher, Intermediate and low severity. Finally frequency of higher severity was found to be nearer to crashes at different site. Therefore the proposed Severity Index will be useful tool for safety assessment of newly designed Unsignalized Intersection which will measure the level of severity of intersection in absolute term. Overall proposed Severity Index is cost effective method to measure the severity of intersection using only video extraction method