Multi-Framework Simulation for Metro Networks: A Cross-Validated Approach in NEXUS

In the context of growing urbanisation and the need of more resilient and adaptive public transport, metro systems face increasing pressure to deliver efficient, inclusive, and responsive services. Within the Horizon Europe project NEXUS, simulation modelling plays a central role in supporting data-driven decisions for operators, planners, and system designers. NEXUS introduces an innovative modelling strategy by developing and cross-validating three simulation models across distinct platforms—AnyLogic, ExtendSim, and Simul8. This multi-framework approach enables a unique comparison of modelling assumptions and outputs, increasing the reliability, generalisability, and applicability of the results. The models build on and extend agent-based and discrete event simulation techniques to capture complex interdependencies between passenger behaviour, infrastructure performance, and operational policies. The simulation models are applied to the Genoa and Sofia metro networks, selected as complementary case studies due to their differing scales and operational complexity. They generate key performance indicators such as travel time, dwell time, train occupancy, and network saturation under both nominal and perturbed conditions. These outputs inform digital twin development and service optimisation, contributing to a more adaptive and resilient metro ecosystem.