UNDERSTANDING THE OVERTAKING BEHAVIOR OF MOTORIZED TWO-WHEELERS ON UNDIVIDED ROAD

Abstract

Overtaking is a complex process as it comprises of series of complicated driving maneuvers, especially on non-lane-based mixed traffic conditions, and the presence of oncoming vehicles (on undivided roads) from the opposite direction on Indian roads make overtaking even more challenging from a safety viewpoint. A review of the literature suggests that the overtaking maneuver performed by MTW riders is one of the primary causes of motorized two-wheeler accidents. The overtaking time is a critical parameter to understand as it determines how safe or evasive the maneuver is often overlooked. Overall, the literature review suggests that very few studies have been conducted to model the total overtaking duration, during which extreme hazards are likely to occur for motorized two-wheelers in heterogeneous traffic conditions, especially in the Indian context. The present study aims to fill this knowledge gap by examining the overtaking behavior of MTW riders and identify the factors influencing the total overtaking duration of motorized two-wheelers in heterogeneous traffic conditions. With the aforementioned discussion and objectives, a field experiment using instrumented motorized two-wheelers was performed on a two-lane undivided road of Roorkee, and 250 overtaking was observed. A methodology based on video and GPS analyses was developed to obtain data describing the MTW's behavior. It was found that the mean overtaking duration was 5.27 sec, and the mean overtaking distance was 61.57m. Also, the overtaking duration for single and multiple overtaking was 4.94sec and 7.83 sec, respectively. Finally, the total overtaking duration was modeled using a hazard-based duration model. The Kaplan-Meier curve was plotted and found that the survival probability was almost 100% when overtaking duration was up to 3secs, which reduced to 53% at 7.5sec and became 8% when overtaking time was 14secs. The parametric accelerated failure time with log-logistic distribution was found to be the best suited for modeling the overtaking duration. The covariates number of vehicles overtaken has the major impact on survival probability, and the covariates overtaking distance, initial distance, final distance had the effect of reducing the survival, while covariates such as initial speed of the following vehicle, speed at the beginning of phase-2, oncoming vehicles, and the speed difference had the effect of prolonging the likelihood of survival. The finding of this study will help to better understand the overtaking behavior of motorized two-wheelers under heterogeneous traffic conditions in the Indian context and pave the way for their safe mobility.