https://www.mdu.se/

Context: As cities grapple with increasing congestion, sustainability concerns, and the need for efficient mobility systems, Mobility Digital Twins (MoDTs) have emerged as promising technology for improving urban transportation. However, the development of MoDTs remains hindered by challenges such as structural complexity, data heterogeneity, lack of interoperability, and limited support for scalability, maintainability, and adaptability. Objective: This work aims to address these barriers by introducing a structured and systematic engineering framework that supports the design development of MoDT, reducing technical debt, development costs and human errors, while promoting long-term evolution. Methods: We propose a Model-Driven Engineering (MDE) approach that organizes the development of MoDTs through models at different levels of abstraction and adopts automated transformations from high-level specifications to executable code artifacts, supporting MoDT life-cycle. Results: The proposed approach is validated through its application in developing a MoDT for the city of Bologna, Italy. To support this, we introduce the M2DT tool, which automates the workflow from high-level models to software code artifacts. The resulting BoMoDT platform is built using open-source technologies and real mobility data. This case study demonstrates the feasibility and effectiveness of our approach, which, to our knowledge, is the first to apply a model-driven strategy for the entire MoDT development. A qualitative evaluation confirms that our framework addresses key challenges in MoDT development. Quantitative experiments further validate BoMoDT's ability to accurately reproduce and monitor real urban mobility conditions. Conclusion: The proposed approach offers a solid foundation for addressing MoDT development challenges. By combining automation with structured abstraction, it improves adaptability and maintainability while enabling scalable integration, helping make MoDTs more accessible for future urban system design.