Rethinking rail track switches for fault tolerance and enhanced performance

Abstract

Railway track switches, commonly referred to as 'turnouts' or 'points,' are a necessary element of any rail network. However, they often prove to be performance-limiting elements of networks. A novel concept for rail track switching has been developed as part of a UK research project with substantial industrial input. The concept is currently at the demonstrator phase, with a scale (384 mm) gauge unit operational in a laboratory. Details of the novel arrangement and concept are provided herein. This concept is considered as an advance on the state of the art. This paper also presents the work that took place to develop the concept. Novel contributions include the establishment of a formal set of functional requirements for railway track switching solutions, and a demonstration that the current solutions do not fully meet these requirements. The novel design meets the set of functional requirements for track switching solutions, in addition to offering several features that the current designs are unable to offer, in particular to enable multi-channel actuation and rail locking, and provide a degree of fault tolerance. This paper describes the design and operation of this switching concept, from requirements capture and solution generation through to the construction of the laboratory demonstrator. The novel concept is contrasted with the design and operation of the 'traditional' switch design. Conclusions to the work show that the novel concept meets all the functional requirements whilst exceeding the capabilities of the existing designs in most non-functional requirement areas.

Measurement of the Geometric Center of a Turnout for the Safety of Railway Infrastructure Using MMS and Total Station

“…Turnouts are an essential element of any railway network. However, they are also capacity constraints [40,41]. There are many types of turnouts, and their properties vary depending on their destination (use).…”

“…A compromise between space, cost, railway-line speed, and efficiency in the choice and location of turnouts should be considered. Bemment et al [40] presented the constraints of turnouts in the performance of a railway network, demonstrating that these constraints arise because turnout (track connection) designs have evolved over time in order to meet a specific objective, which, at the same time, means that turnouts may not be optimized to provide the performance that a modern network requires. The authors defined the formal requirements for track connection solutions, arguing that traditional solutions do not meet all of the requirements, and additionally presented an innovative solution for track connections called the "Repoint" solution.…”

On the development of a full-scale Repoint Light track switch

“…Initially, a document was developed to capture applicable and relevant railway switching specifications and regulations from British and European standards, as well as input from relevant stakeholders (RSSB, Network Rail and TfL) regarding essential and desired requirements. Systemlevel architecture and single bearer mechanical design have evolved through different technology readiness levels [3]. Design improvements in comparison to previous versions are described later in this section.…”

“…In the novel Repoint approach, a bank of in-bearer type electro-mechanical actuators, featuring integral passive locking elements with detection system, allows multi-channel actuation providing a high degree of fault tolerance [3,4]. The concept, based around a stub switch panel, offers several features improving current designs.…”

Rethinking Rail Track Switches for Fault Tolerance and Enhanced Performance

“…The remaining solutions were scored and ranked based on the degree to which they met the functional and non-functional requirements. A more detailed account of the ranking and evaluation process can be found in Bemment et al (2016) …”