Heterogeneous traffic flow modelling: a complete methodology

A comprehensive methodology for modelling the heterogeneous traffic is presented in this article. Considering the no-lane discipline and the presence of various sizes of vehicles, several microscopic and macroscopic traffic variables are analysed for their suitability in describing the heterogeneous traffic. Applicability in the modelling process and the feasibility in collecting field data are the important criteria used in deciding the suitable traffic variables. In place of occupancy, its variant termed as area occupancy was found to be suitable in describing the heterogeneous traffic. Vehicle size, mechanical characteristics, lateral distribution of vehicles and the lateral gaps maintained by them are found to be more suitable microscopic traffic variables. Data on these variables have been used in modifying the cell structure and the updating procedures of the cellular automata (CA)-based traffic flow model. A customised video image processing-based data collection technique has been used in collecting the field data on these variables. The modified CA model with the relevant parameter values has been used in simulating the flow. Model results are validated using the field data and the results expressed in terms of cells are found to be better in capacity analyses under heterogeneous traffic conditions as well as fit into the established traffic flow theory.