Modelling Trolleybus Networks: a Critical Review

The trolleybus system is already part of the urban environment of several metropolitan cities. In view of the emergence of smart cities, it appears reasonable to look at how the trolleybus grid can become a more active part of the urban's electricity network. However, the infrastructure design approaches adopted so far make the current trolleybus networks overdesigned to handle the improbable worst-traffic case scenarios. Consequently, the trolleybus electrical supply system is both underutilized and oversized. Through modeling, simulations, and a cluster of measured trolleybus and corresponding network data, various new functionalities may be explored, among which electric vehicle chargers and energization of auxiliary equipment, towards a more sustainable and smart trolleybus grid. This paper merges the authors' engineering knowledge and sources available in the literature on designing and modelling trolleybus networks and performs a critical review of them to lay the foundations for proposing possible optimal alternatives. Being the city of Bologna organized with multiple electrically powered zones with either basic or complex topologies, the respective trolleybus system has been chosen as a case study.