Designing a public transport network involves more than adding routes or increasing service frequency. Transport planners need to understand how people move across a city, where connections are missing and how changes to one line may affect journeys elsewhere. Leipzig provides an example of how transport modelling can support these decisions and help planners assess different network configurations before implementing them.

Leipzig’s public transport operator, Leipziger Verkehrsbetriebe (LVB), is exploring automated network design in PTV Visum to prepare for expected changes by 2040. The city’s population is projected to grow by around 5% between 2025 and 2040, while public transport demand could increase by approximately 17%. This difference makes it important to consider not only how much service to provide, but also where routes should run and how they should connect.

Instead of manually developing every possible tram network, planners define objectives and constraints, including passenger demand, available infrastructure, service standards, fleet availability, budget limits and operational requirements such as turnaround times. The software can then generate and evaluate alternative network configurations within the existing transport modelling framework.

The aim is not to let an algorithm decide the final network. Automated design allows planners to examine more options within limited time and resources, while retaining responsibility for assessing feasibility and local conditions.

The Leipzig experience highlights four important factors: reliable input data, realistic operational constraints, transparent evaluation criteria and continued involvement of planning experts. Automation can make the assumptions behind alternative designs more explicit and reproducible, helping teams explain why certain options perform differently.

The initial work focuses on future tram network scenarios, and further development is needed, particularly in defining optimisation objectives and integrating multiple transport modes. Nevertheless, the approach could help public transport authorities make long-term planning more systematic.

For cities facing rising demand and constrained budgets, automated network design offers a way to explore more possibilities before committing to infrastructure or service changes. Its greatest value may lie not in producing one supposedly perfect network, but in helping planners understand the trade-offs between passenger demand, operating costs, service quality and available resources.

You can find the original article here.
 
SCHILDE, Matthias. Transit Network Design: Lessons from Leipzig's 2040 Planning. PTV Blog [online]. September 2, 2026 [cited 2026-10-21]. Available from:  https://blog.ptvgroup.com/en/user-insights/transit-network-design-leipzig/

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