Simulation of rail traffic: methods for timetable construction,delay modeling and infrastructure evaluation

This thesis covers applications and proposes methods for using simulation in a more effective way and also in a wider context than normally used. One of the proposed methods deals with delay modeling that can be used in a calibration process. Furthermore, a method is presented that facilitates the management of having timetables, infrastructure scenarios and delays as variables in simulation studies. The simulation software used in this thesis is RailSys, which uses a microscopic formulation to describe the infrastructure and train movements. Timetable changes with respect to allowances and buffer times are applied on a real case (Western Main Line) in Sweden in order to analyze how the on-time performance is affected for high-speed passenger trains. The potential benefit is that increased allowances and buffer times will decrease the probability of train interactions and events where the scheduled train sequence is changed. The on-time performance improves when allowances are increased and when buffer times concerning high-speed trains are adjusted to at least five minutes in locations with potential conflicts. One drawback with this approach is that it can consume more space in a timetable at certain locations, hence other trains may need adjustments in order reach these buffer times. Setting up simulations, especially in large networks, can take significant amount of time and effort. One of the reasons is that different types of delay distributions, representing primary events, are required in order to obtain conformity with reality if a real timetable and network is modeled. Considering train registration data in Sweden, the separation in primary and secondary delays is not straightforward. The presented method uses the basic train registration data to compile distributions of run time deviations for different train groups in a network. The results from the Southern Main Line case study show that a reasonable good fit was obtained, both for means and standard deviations of delays. A method for capturing the variance in freight train operations is proposed, partly based on the findings from the aforementioned study. Instead of modeling early freight trains on time, the true initiation distributions are applied on time-shifted freight trains. In addition to the already mentioned methods, which are applied on real networks, a method for reducing the uncertainties coming from assumptions of future conditions is proposed. It is based on creating combinatorial departure times for train groups and locations and formulating the input as nominal timetables to RailSys. The dispatching algorithm implemented in the software can then be utilized to provide feasible, conflict-managed, timetables which can be evaluated. This can be followed by operational simulations with stochastic delays on a subset of the provided timetables. These can then consequently be evaluated with respect to mean delays, on-time performance etc. To facility the use of the infrastructure as a variable in these type of studies, an infrastructure generator is developed which makes it relatively easy to design different station layouts and produce complete node-link structures and other necessary definitions. The number, location and type of stations as well as the linking of stations through single-track or multi-track sections can be done for multiple infrastructure scenarios. Although the infrastructure can be defined manually in RailSys, a considerably amount of time and effort may be needed. In order to examine the feasibility of this method, case studies are performed on fictive lines consisting mostly of single-track sections. This shows that the method is useful, especially when multiple scenarios are studied and the assumptions on timetables consist of departure intervals for train groups and their stop patterns.

Language

  • English

Media Info

  • Pagination: 98
  • Serial:
    • TRITA-TSC-PHD
    • Issue Number: 15-001
    • Publisher: KTH Royal Institute of Technology, Sweden

Subject/Index Terms

Filing Info

  • Accession Number: 01631253
  • Record Type: Publication
  • Source Agency: Swedish National Road and Transport Research Institute (VTI)
  • ISBN: 9789187353642
  • Files: ITRD, VTI
  • Created Date: Mar 30 2017 12:14PM