Analysis of Overtaking Behaviour on Undivided Two-Lane Roads in Hilly Region

Indian roads experience heterogenous traffic conditions with variations in static and dynamic features of vehicles. The major problem that the roads face is that the vehicles do not adhere to the strict lane discipline and readily occupy the lateral spaces on the road. Overtaking process involves lane changing maneuvers, acceleration and deceleration actions and also estimation of speed and distance of the oncoming vehicles. The analysis of vertaking maneuvers revealed distinct trends among vehicle pairs. Predominantly, the highest frequency of overtaking instances occurred between cars and two-wheelers, accounting for 26.49% of occurrences with cars being the prevailing overtaking vehicles. Following this, car-car pairing exhibited 20.51% of overtaking occurrences. Moreover, the study underscored that overtaking times is influenced not only by the type of vehicles overtaken but also by the road gradient. Generally, overtaking durations correlated positively with increased road gradient, except notably at site 4, where a 1.343% gradient showcased an unexpected trend. Furthermore, the outcomes derived from the Multiple Linear Regression (MLR) model underscored the significant impact of road gradient, type of overtaking vehicles, speed of overtaking vehicles and acceleration on overtaking duration, reflected in their respective coefficient values of 1.122, −0.25, −0.16 and 0.13 respectively. This highlights their substantial role in shaping overtaking dynamics on roadways. Overall, this research underscores the substantial impact of road gradient on the calculation of overtaking sight distance, emphasizing the crucial need for Transportation Engineering to prioritize the inclusion and analysis of road gradients in their assessments.