More trains or lower operating costs? Greater capacity or fewer emissions? When it comes to improving performance, every decision comes with a trade-off. But how can operators know whether a change will deliver as expected, before actually implementing it?
That’s where decision-support tools come in.
Within NEXUS, STAM developed MOBIUS: a transport network digital twin that combines simulation and optimisation in a single platform.
Simulation lets operators feed in a network’s topology, service schedule and passenger demand, run it, and get back key performance indicators: passenger waiting and journey times, crowding, fleet utilisation, energy consumption and CO₂ emissions. This means operators can test assumptions and hypotheses before putting them into practice, allowing operators to ask any what-if question that comes to mind and test it immediately.
Optimisation builds on that same simulation engine to search for near-optimal solutions that balance passenger experience, operating costs and available resources. Rather than testing one scenario at a time, it runs through many scenarios quickly, searching for the best combination of parameters. Put simply, the Optimisation feature answers two core questions for operators: how long should vehicles wait at each station, and how often should they run? Together, these two questions define the timetabling problem.
Under NEXUS, STAM applied MOBIUS to two real metro networks: AMT’s network in Genoa, Italy, and Sofia Metro network in Bulgaria. The results, presented in detail in Deliverable 7.2 (soon available on our Repository), were promising for both operators. For AMT, the analysis showed that the required fleet size could be reduced by up to 22%, with only a small increase in passenger waiting time and no meaningful change in train travel times. For Sofia Metro, MOBIUS uncovered effects specific to individual lines, such as the impact of closing Serdica station, that a network-wide average would have masked. Across almost every scenario tested, the optimised configurations also lowered energy consumption and CO₂ emissions, in some cases by more than 20%.
MOBIUS supports smarter, data-driven, decision-making and aligns with NEXUS’s goal of providing European metro operators with practical tools to plan more efficient, resilient and sustainable services.