Modeling of shared mobility services - An approach in between aggregate four-step and disaggregate agent-based approaches for strategic transport planning

Shared mobility services are slowly penetrating European cities. Hence, transport models that are capable of modeling them are fundamental, to support policy-makers for making informed decisions. Many European cities, especially the small- and the medium-sized ones, continue to use the traditional four-step modeling approach. This approach does not have the necessary capacity to model the shared mobility services and there is a need to extend them. Hence, this research proposes an extended framework, which includes modules for synthetic population generation and fleet management. Furthermore, modules are also suggested for the estimation of emissions, car-ownership and induced demand, as such measures are increasingly expected by cities. Multiple equilibrium checks between the aforementioned modules are avoided in the design of this development, to reduce model complexity and convergence issues. The models and the algorithms used for the additional modules in this study can be replaced with alternative equivalent models, provided the inputs and outputs are consistent with the framework. As such, the framework is software agnostic. Based on a case study on the city of Thessaloniki, a proof of concept is provided. The intermediate modeling framework, proposed in this study, provides an opportunity for cities to evaluate and integrate shared mobility systems and form long term planning strategies. Besides, it acts as a bridge between the worlds of simple and complex modeling approaches and pave the way for reducing the reservations of the cities toward complex approaches, while preparing them for a smoother transition in future.