To build or not to build -- A queueing-based approach to timetable independent railway junction infrastructure dimensioning
Tamme Emunds, Nils Nießen
TL;DR
The paper develops a timetable-independent method for railway junction capacity using a route-based Continuous-Time Markov Chain (CTMC) coupled with probabilistic model-checking to evaluate infrastructure layouts without timetable data. By modeling route conflicts and multi-channel service, it computes queue-length metrics $E_{LW,i}$ and compares layouts (e.g., with/without an overpass) against threshold-based quality criteria $L_{W,\text{limit}}$. The approach is validated against simulations and applied to a computational study over 529 operating-program combinations, revealing that overpasses can meaningfully reduce the required maximum mean service times in many high-load scenarios. This framework supports early-stage infrastructure dimensioning and rapid decision-making for junction design, contributing a fast, analytical alternative to simulation-based capacity analysis in railway planning.
Abstract
Many infrastructure managers have the goal to increase the capacity of their railway infrastructure due to an increasing demand. While methods for performance calculations of railway line infrastructure are already well established, the determination of railway junction capacity remains a challenge. This work utilizes the concept of queueing theory to develop a method for the capacity calculation of railway junctions, solely depending on their infrastructure layout along with arrival and service rates. The implementation of the introduced approach is based on advanced model-checking techniques. It can be used to decide which infrastructure layout to build, i.e. whether an overpass for the analysed railway junction is needed. The developed method hence addresses the need for fast and reliable timetable independent junction evaluation in the long-term railway capacity calculation landscape.