Timetabling Problems With Holding Decisions and Fuzzy Synchronization Functions

This paper presents an optimization approach for the Intermodal Timetable Synchronization Problem that can be used to explore the impact of holding decisions and departure flexibility in an isolated and integrated way for different scenarios. It also introduces the concept of fuzzy synchronization to protect the solutions against variability in travel times caused by external factors, such as congestion. The methodology was applied to the transit network of Metrorrey in Monterrey, Mexico, assuming three planning periods along a weekday. It was found that considering holding decisions leads to significant improvements when generating synchronous timetables at transfer stops. Furthermore, three different types of variability were simulated, and their effects on four different fuzzy synchronization functions were evaluated. Thus, we provide a tool to analyze different scenarios and to support decision-makers in the planning stage of public transport systems. The analysis can be extended considering other types of travel time variability and nonlinear synchronization functions.