Redundantly Engineered Track Switching for Enhanced Railway Nodal Capacity

Abstract

Railway track switching provides necessary flexibility to a rail network. However, the inclusion of switches also introduces single points of failure and restricts system capacity through train control rules. Historically, switching practice has evolved with safety as the ultimate priority with minimal consideration given to how the design, and its associated control systems, detracts from maximum network capacity - primarily as switches have rarely been the limiting factor. Over recent years, capacity has become more critical. As rail systems are improved, the traditional design of track switch and control methodology represent an ever increasing portion of theoretical maximum network capacity which cannot be utilised. Herein, an example of this capacity limit is presented. The proposed HS2 (High-Speed 2) rail link in the United Kingdom, where metro-frequency services are proposed to run on 250mph lines, is pushing the boundaries of what current technology can offer. Some industries have resorted to functional redundancy to provide the fault tolerance necessary in similar mission-critical systems, without sacrificing safety. This paper builds upon earlier published work by evaluating novel track switching concepts incorporating functional redundancy in terms of the potential to boost capacity. Possible changes are discussed, and potential implications of those changes are quantified using a model of a typical HS2 node in Railsys. Maintainability and cost implications are outlined. Results demonstrate that a substantial revision of track switching practice can yield a large percentile increase in the capacity of the junction; in the HS2 case matching the capacity of the adjoining plain line.