Fakultät für Maschinenbau und Sicherheitstechnik

Modelling mixed urban traffic

In a city, the street network is heterogeneous in terms of composition but also of infrastructure due to the adaptation of the layout to more and more different users. Current urban traffic  flow in European city centers are composed of road vehicles, pedestrians, bicycles, scooters, and other motorized or not personal mobility devices (PMD). The conception of intelligent transportation systems is generally based on simulation analyses. Numerous models exist for the different types of users, e.g. car-following models for traffic flow or force-based models for pedestrian crowds. However, only few studies address the interactions between agents of different types (e.g., pedestrians and cyclists). These questions rely on modeling the flow heterogeneity and associated interaction mechanisms.

Static heterogeneity in the agent characteristics

We consider in the first heterogeneity model two agent types and attribute statically two parameter settings to the two agent types. We aim here to model different agent types (for instance, pedestrians and bicycles) with specific characteristics in terms of desired speed, agent size, etc. This kind of heterogeneity is usually called quenched disorder in solid-state physics. It refers to static heterogeneity features remaining constant (i.e., quenched) over time. Such a mechanism results in the formation of lanes.

Dynamic heterogeneity in the interactions

In the first heterogeneity model, we attribute dynamically the two parameter settings according to the type of the closest agent in front. The parameter setting is the first one if the agent in front is of the same type, while it is the second in case of interaction with another agent type. Such a mechanism may be realized in mixed urban traffic where cyclists or electric scooter drivers adapt their behaviour, e.g., increasing the time gap or reducing their desired speed, when following a group of pedestrians. The heterogeneity features are time-dependent. They are usually called annealed disorder in the literature. Interestingly, such a mechanism results in the formation of bands.


B. Khelfa, R. Korbmacher, A. Schadschneider and A. Tordeux, (2022) Heterogeneity-induced lane and band formation in self-driven particle systems, Scientific Reports, vol. 12, no. 1, pp. 1-11. Nature Publishing Group.

B. Khelfa, R. Korbmacher, A. Schadschneider and A. Tordeux (2022) Initiating Lane and Band Formation in Heterogeneous Pedestrian Dynamics, Collective Dynamics, vol. 6, pp. 1-13, 2022.

NetLogo online simulation module for the formation of lanes and bands


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