Driver Heterogeneity in Car following and Its Impact on Modeling Traffic Dynamics

A dedicated trajectory data collection method using a helicopter enabled a range of in-depth empirical studies of car-following behavior. These studies found a high degree of heterogeneity in car-following behavior; that is, drivers' driving styles turned out to be highly different because different modeling approaches were needed to model these behaviors satisfactorily. Therefore the impact of heterogeneity in car following on modeling traffic dynamics is examined to gain insight into the effect of incorporating different types and degrees of heterogeneity in car-following behavior on the dynamics of a simulated traffic flow. The microsimulation approach that was adopted focused on two case studies: the first case study focused on heterogeneity in parameter values by comparing stability results for heterogeneous platoons and homogeneous platoons, which could in fact be seen as a solid preparation for the second case study. The second study was a simulation of a fixed stretch of road on which, from a certain point on, a speed limit was imposed for the drivers. In this case study the link between the empirical results and the simulations was strengthened as several types of heterogeneity (e.g., different model specifications for different drivers and different parameter settings and combinations of them) were explored and compared with the empirically estimated parameters. Both analyses show clear differences between simulations with homogeneous drivers and simulations with heterogeneous drivers.