A systematic approach to evaluating operations of virtually coupled trains

Download Statistics

Downloads

Downloads per month over past year

Erdem, Alican (2024). A systematic approach to evaluating operations of virtually coupled trains. University of Birmingham. Ph.D.

Preview

Erdem2024PhD.pdf
Text - Accepted Version
Available under License All rights reserved.
Download (13MB) | Preview

Abstract

Railway transport holds prominence as a viable alternative to road and air modes. With the demand for rail expected to continue its upward trend, stakeholders are seeking innovative solutions to boost rail traffic volume. Virtual Coupling (VC) has been proposed as a concept that enables trains to run closer than existing operations. This can be achieved in a way that two or more trains become engaged with each other so much that they move like a single unit via synchronous acceleration and braking. VC operations, when deployed, are expected to increase line capacity. However, rail lines are so complex that capacity enhancement is not simple and straightforward. Some studies and projects have conducted research on VC, but a systematic approach to evaluating the capacity enhancement of VC operations has not yet been developed. This study has made an original contribution to VC research by developing an evaluation framework for assessing the VC operational performance.

As a step of concept exploration, VC was defined from an operations perspective. The study categorised VC operations from two viewpoints including convoy formation and safe distance principle. Two types were defined through the convoy formation: In inter-consist one, two or more trains are virtually coupled with each other, whereas in intra-consist one, one train is split into smaller sub-trains. From the viewpoint of braking principle, VC operations were defined on the basis of either Absolute Braking (AB) or Relative Braking (RB).

The study has defined four basic operational scenarios depending on where coupling and/or uncoupling occur: at stations or around junctions and then, has developed a simulation architecture to assess capacity performance for these scenarios. The simulation results indicate that under ideal conditions, VC on RB can deliver a capacity of 240 train per hour for a plain line, but this performance is confined by switch processing times for the scenarios including diverging or converging route. VC on AB deliver a capacity ranging from 60 to 70 train per hour for all the scenarios. Also, it was found that intra-consist operation reduces energy use and travel time, especially for express high-speed train services. In addition, the study has investigated influencing factors on VC performance by conducting sensitivity analysis. The following factors were found effective on capacity performance and important in creating a VC operational plan: braking capability, adhesion, fleet heterogeneity, station layout and platform length, relativity index, number of trains in a convoy, virtual interlocking type.

The evaluation framework, developed by this study and presented with the IDEF0 notation, is the first one that creates a systematic approach to evaluating VC operations on a rail line against its existing performance. The framework has been demonstrated through a case study. The London Waterloo to Surbiton line section was analysed over a VC operational plan of nine scenarios with varying safety levels and convoy types. The simulation results indicate a potential capacity increase of two to four times, contingent on fleet expansion with additional 40 to 80 stocks. However, delay propagation is an issue as per deterministic perturbation scenarios, suggesting reducing convoy sizes and increasing time intervals between them as a resilience strategy.

Type of Work:

Thesis (Doctorates > Ph.D.)

Award Type:

Doctorates > Ph.D.

Supervisor(s):