Macroscopic modelling of heterogeneous disordered road traffic flow

Abstract

The groundwork for much of the existing traffic flow theory was laid in the 1950s and 1960s by researchers from developed economies like the United States. The car-following modelling approach, which is arguably the most popular type of microscopic traffic flow models, and the kinematic wave modelling approach, which is still the basis for much of the macroscopic traffic flow theory, were first introduced during this period. Because the object of this and much of the subsequent research it has spawned is the traffic of developed economies, the classical traffic flow theory deals almost exclusively with this specific kind of traffic: lane-disciplined with relatively homogeneous passenger car traffic. However, the traffic in many developing economies have a significant share of two and three-wheeler motorized vehicles and non-motorized vehicles with different static and dynamic characteristics, resulting in a fundamentally different traffic stream. Because of the differences in sizes and manoeuvrabilities, the vehicles in this traffic stream do not follow the lane-discipline. This kind of traffic has been described in the literature as heterogeneous, disordered (HD) or mixed traffic. These developing economies, mostly from Asia and Africa, are rapidly urbanizing and the need to deal with the challenge of traffic congestion is more urgent than ever. Given that these countries are already struggling to keep pace with the rising urban population for providing the necessary road infrastructure, it may be more effective to make the most efficient use of the existing infrastructure through the use of traffic management solutions like real-time traffic monitoring and signal control. As such solutions cannot be formulated using the traditional traffic flow theory, an alternative theory that explicitly considers the characteristics of the HD traffic is urgently needed. In the present study, HD traffic is characterised by the division of its component vehicle classes into car-following and gap-filling types...