Modeling Duration of Lateral Shifts in Mixed Traffic Conditions

Abstract

Traffic on urban roads in developing countries is characterized by wide mix of vehicles with loose lane discipline, which results in parallel movement of vehicles in the same lane. Hence, vehicles not only interact longitudinally with the vehicles ahead but also laterally with vehicles to the sides. Lateral movements have a significant impact on the characteristics of traffic flow and therefore are of great importance in microscopic traffic simulation models. Existing simulation models for mixed traffic conditions model lateral shifts (lateral movements) as an instantaneous process but neglects detailed modeling. However, the duration for lateral shifts is generally in the range of .5–15 s. The omission of lateral shift duration from simulation models may have a significant impact on simulation outputs. Also, different vehicle types may have different lateral shift durations due to variations in their physical and operational characteristics. This paper attempts to develop a vehicle-specific lateral shift duration model by considering different explanatory variables such as direction of lateral shift, available space gaps, speeds of subject vehicle and surrounding vehicles, vehicle types, and clearance. The models were estimated using trajectory data collected during medium-flow conditions from an urban arterial in Chennai city, India. The findings from this study have direct implications on modeling lateral shifts in microscopic traffic simulations to be developed specifically for mixed traffic conditions.