Integrated Urban Mobility Policies in Metropolitan Areas: A System Dynamics Approach for the Rhine-Ruhr metropolitan region in Germany.

In today's world, urban systems play an important role in sustainable economic development. In particular, urbanisation trends and the increasing demands of urban mobility place additional pressure on existing transportation infrastructure, and this creates new challenges for urban planners in terms of developing integrated and sustainable urban mobility policies. Here, we take a novel and holistic approach to analysing transformative pathways towards sustainable urban mobility, considering the complex dynamics in metropolitan regions. To achieve this, we develop a toolset to assess the impact of potential measures to be taken by decision makers. Our innovative approach is based on the introduction of a new system framework to link the interrelated sector parameters of mobility systems by considering the effects of innovative mixed methods (both qualitative and quantitative) on scenario development and evaluation on the basis of global trends at the macro scale and their specific influences on the mobility sector at the local scale. To this end, we used a participatory modelling approach to develop scenarios and evaluate them as integrated simulation runs via a comprehensive and holistic system dynamics (SD) model. Thus, we estimated dynamic interdependencies between all of the factors relating to the mobility sector and then assigned business decision-making criteria to the urban systems. Furthermore, we introduced a sustainable net present value framework to estimate the sustainability outcomes of government investment in urban mobility infrastructure. A case study relating to the Rhine-Rhine-Ruhr metropolitan region in Germany was applied in order to simulate four scenarios co-created with stakeholders involved in our study, namely, Smart City, Sustainable/Healthy City, Deurbanisation and Business-as-Usual (BaU), which served as a solid basis from which to quantify path dependencies in terms of policy implementation. At the same time, recommendations were derived for sustainable mobility transformation within metropolitan regions.