Routes Management in Complex Railway Junctions: Methodology and Tools for Optimizing Operation and Layout

This paper describes the methodology used to create a model for supporting the definition of an efficient timetable given a station layout. The objective is to assess the capacity of the physical infrastructure in terms of simultaneous movements in a defined time horizon. A computational procedure (software SNJ) is formalized to perform a morphological analysis of junctions themselves. It returns an indicator of capacity (mean number of possible safe movements) and the list of the n-tuples capable to saturate the station. In a stable state condition different combinations of n-tuple activations could return very different levels of capacity. Following the identification of a mathematical formulation (model SLC) and a solution algorithm, a software is implemented (coded in APL) for being able to face capacity problem in any complex layout. The Station Layout Computing (SLC) model described in the paper, allows to find the optimal solution in terms of activation frequency of each n-tuple satisfying the timetable demand efficiently, i.e. in the shortest possible period of time. The computational analysis evaluates the performance of a realistic station layout under real operational conditions. It allows to determine the combination of n-tuples that provides the highest number of train movements in the time horizon, respecting all scheduled frequencies (respecting scheduled frequencies on all lines). This solution optimizes the layout utilization, sets additional feasible movements and proves layout reliability. Such a reliability is assessed through the leftover time values that can be used to deal with operating variances or perturbations (uncertainly of arrivals, prolongations in the stopping).