Cell Transmission Modeling of Heterogeneous Disordered Traffic

Several macroscopic approaches exist for modeling the flow of the vehicular traffic in the developed economies, from kinematic wave models using first-order or higher-order systems of partial differential equations to spatially and temporally discretized models like cell transmission models and noncontinuum models that treat traffic as a collection of dynamic systems. The adaptation of these modeling approaches to the traffic in developing economies is made difficult by the latter’s high levels of heterogeneity and weak lane discipline. However, most of the existing studies on heterogeneous or multiclass traffic implicitly assume lane discipline. In the present article, the notion of heterogeneity in the contexts of developed and developing economies is discussed. It is argued that the differences in their aggregate traffic behaviors are a direct result of the presence of the small-sized, highly maneuverable vehicles like motorcycles and auto-rickshaws. In addition, vehicles are classified into two types: car-following and gap-filling, and two different forms of fundamental relationships are derived using some simplifying assumptions. Finally, a heuristic cell transmission model that is capable of reproducing the vehicle creeping phenomenon that is a salient feature of the heterogeneous, disordered traffic is presented, and its results are compared with those of a numerical scheme for a multiclass Lighthill-Whitham-Richards model.