Two-Dimensional Following Behavior Analysis of Powered Two-Wheelers Using Copula Approach

This paper reports a comprehensive investigation regarding the staggered following behavior of the powered two-wheelers (PTWs) in multi-class disordered traffic. The real-world trajectory data of such traffic stream was collected for this purpose and processed further to obtain the information on essential characterizing variables. The study adopts a two-layer framework. In the first phase, the spatial variables that characterize such behavior were identified, and their variation pattern was observed. More importantly, answers to two specific questions regarding the movement pattern of PTWs was obtained: (i) Whether the movement pattern of PTWs differ according to the type of lead vehicle they are following? (ii) Does it change according to the side in which the following is done? The second phase aimed at modeling the dependence between lateral and longitudinal descriptors of PTWs following behavior to precisely describe its movement pat-tern. The applicability of the copula approach was investigated for this purpose, and the obtained results indicated that Frank copula could model the joint distribution for almost all leader-follower vehicle pairs. The results also highlighted the importance of considering lateral separation for a realistic representation of multi-class disordered traffic streams. The developed models would contribute to better simulation models to represent the movement of PTWs in such traffic streams.