On the transformation of public mobility services toward more sustainability

Dirks, Nicolas Bernd Frank; Walther, Grit (Thesis advisor); Kuhnimhof, Tobias Georg (Thesis advisor)

Aachen : RWTH Aachen University (2021, 2022)
Dissertation / PhD Thesis

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021


In the fight against climate change, poor air quality in inner cities, and the finite nature of fossil resources, the world is undergoing a cross-sector transformation toward more sustainability. As the transportation sector relies to a large extend on the combustion of fossil fuels, a transformation of this sector is crucial. In particular, public mobility services need to transform in order to reduce the inherent global and local emissions, but also to counter the dependence on private car ownership. Against this background, this cumulative dissertation consists of four publications that all contribute to the transformation toward (more) sustainable public mobility services. All publications are either already published or are under review in peer-reviewed academic journals in the field of transportation planning. The dissertation is divided into two major parts with each two publications. The first part addresses a transformation path of public mobility services in urban areas, namely the integration of battery electric buses into urban bus networks, as they contribute to the reduction of harmful pollution concentrations in inner cities. With energy by renewables, battery electric buses also reduce global greenhouse gas emissions and the consumption of fossil resources. The second part addresses a transformation path of public mobility services in rural areas, namely the integration of multimodal mobility hubs, as they link on-demand modes with public transportation, in particular to overcome the last-mile and to reduce the reliance on private car ownership. The two parts are framed by a preface and a conclusion. The first publication is a concise guide on designing decision-support tools for the integration of battery electric buses into urban bus networks for both practitioners and academics. In a first step, practitioners' requirements for integrating battery electric buses are derived from state-of-the-art specifications, project reports, and expert knowledge. In a second step, the fulfillment of the identified practitioners' requirements by state-of-the-art scientific approaches is analyzed. Based on this analysis, the gap between practice and research is outlined. The second publication includes a novel optimization-based model for determining a cost-optimal transformation plan for the integration of battery electric buses. Among others, it covers fleet planning, positioning of charging infrastructure, and operational planning. The planning model is suitable for real-world applications and narrows the gap of a strategic transformation planning model that anticipates the operation, while accounting for partial recharging at charging stations within the bus network. Based on a real-world case study, valuable managerial insights, e.g., regarding the feasibility and competitiveness of battery electric buses as well as beneficial technical specifications, are derived. The third publication presents a new (intuitive) methodology to identify critical connections within (public) transportation systems, especially for decision-makers in rural areas. The approach bases on a comparison of the indicators travel demand and travel velocity. Any connection is classified based on these two indicators in order to derive needs for action. For example, improving a connection with a high travel demand and a low travel velocity is considered to promise high improvements regarding the accessibility to points-of-interest and workplaces. The methodology is applied to a real-world case study in a rural region. The fourth publication introduces a novel decision support tool based on an optimization-based model for installing multimodal mobility hubs, while aiming at improving the accessibility to points-of-interest as well as to workplaces. The model covers decisions on locations of multimodal mobility hubs, the available on-demand modes, the required parking spaces, and the newly enabled travel itineraries. Based on the enabled travel itineraries, the overall accessibility to points-of-interest and workplaces is improved. Among others, the impact of direct car sharing itineraries on the accessibility improvements is analyzed within a case study for a rural region.


  • Chair of Operations Management [813510]