Evaluation of Fluctuating Speed and Lateral Movement of Vehicles: Comparison Between Mixed Traffic and Homogeneous Traffic

Abstract

Urban roads in developing countries become congested more often because of the substantial lateral movement of vehicles and fluctuations in speed. Popular microscopic models such as car-following and lane-changing models are not suitable for the analysis of such traffic conditions unless some modifications accounting for heterogeneity are included. However, there seems to be an underlying mechanism behind the fluctuations that needs to be investigated thoroughly. The Hurst exponent concept of chaos theory was used to identify the hidden trends in vehicular movement. Real-life trajectory data from an urban arterial in Chennai, India, were analyzed and then compared with a homogeneous data set in the United States. The Hurst exponent for mixed traffic was found to be significantly less than that for the homogeneous data; this finding indicated the strong trends of lateral movement and speed in homogeneous traffic. The variation of Hurst exponents with vehicle type and average lateral positions was explored in mixed traffic. Results from this study will help modelers propose better microscopic simulation models accounting for the fluctuations in speed and lateral movement.