Back 2 Basics

Part 1

Looks at the essentials of ‘interlocking’ and focuses primarily on the technology used for interlocking, from mechanical systems through to multi-channel computer systems (e.g. 2oo2, 2oo3). The article explores what "interlocking" means, how it has evolved from the original mechanical interlockings through to sophisticated computer-based interlockings (CBI), how the system architectures ensure safety, and how interlockings are interfaced to both control centres and trackside equipment. Finally, the possibilities for the future evolution of interlockings are also explored. Published in April 2020

Link to article is here

Part 2

This part focuses primarily on the functional requirements of an interlocking and what it actually does in practice. It explores: Checking route availability. Route setting and route locking. Overlaps. Clearing the entrance signal. Route holding and route release. Approach locking. Releasing the overlap. Scheme Plans. Control tables. Published in May 2020

Link to article is here

Describes the overall purposes of a train control system, covering safety and operational requirements. The requirements are an extended set that was originally set out in the IRSE Signalling Philosophy Review [2001], later revised in a paper to the IRSE on Signalling Philosophy, Principles and Practice by Francis How [2004] and subsequently reviewed and further revised by the IRSE’s Education and Professional Development Committee during 2013/14. The requirements were formatted into the IRSE News B2B style and slightly but not significantly updated. Published in October 2019.

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The article covers the use of latched relays for route locking and for point control. Relays come in many forms including neutral, biased, dual wound, AC immune, slow to operate, slow to drop and latched. With the exception of the latched types, they all share a common characteristic that when you remove the feed to the coil(s) the relay will revert to a de-energised state. The latched relay is different in that it remains in the state to which it was last changed before the feed to the coil was removed. For those of you more familiar with electronic technology and computing, a latched relay is the equivalent to nonvolatile memory whereas the other types are more like random access memory in that when the power is lost the memory is lost too. Published April 2021

Looked at level crossings (also called grade crossings and rail crossings) and the interfaces between rail traffic and roads/pathways. The article identifies and considers the factors which are relevant to the provision and safe operation of level crossings. The article draws on UK practice to address the generic factors, and notes that legal and cultural differences prevail in many countries which may override the generic principles set out in the article. The article includes: What are level/grade crossings and why do railways have them? Legal requirements. Safety. Selecting the right type of crossing for a particular location. Equipment for protection and warning at crossings. Communication systems for crossings. Automatically operated crossings. Cab signalling and level crossings. Together with future developments. Published April 2021

Link to article is here

Low-capacity lines cannot justify costly signalling solutions, so many of the world’s railways maintain train safety and regulation with train controllers issuing authorities to train drivers verbally over a train radio system. In Australia this safe working system is defined as Train Order Working whereas in the United States, New Zealand and Canada it is known as Track Warrant Control, Direct Traffic Control or Form D Control. The article looks at manual train authority systems and their electronic/computer‑based modern equivalents. It also considers additional safety features such as trackworker protection, movement authority enforcement, train integrity management, and train location reporting. Published November 2021

Link to article is here

Most engineers, regardless of where they are in career paths, can identify people who today, or in the past, have been ‘mentors’. People that have been there as skills and experience develop, people that are ready to listen, ask questions to make people think about their options and next steps, and to just be there to help when needed. This article concentrates on the form of mentoring where there is a voluntary one-to-one relationship which enables one person (the mentee) to benefit from the advice and guidance offered by a more experienced ‘mentor’. It expands on the IRSE Guide to Mentoring, and goes ‘back to basics’ to consider what is meant by ‘mentoring’, and how it can bring real value to all concerned. Published October 2022.

Link to article is here

Robert Cooke, Mark Glover and Richard Roberts, three of the team behind the new IRSE textbook, Metro Train Control Systems, introduce the underpinning principles that make train control for metro railways different to other types of railways. The article looks at some of the unique challenges that engineers working on this type of network face and identifies some of the solutions that tend to be used when current systems are installed or upgraded. Metro railways; mass transit railways; subway; tube. Automatic train protection (ATP); Automatic Train Operation (ATO); Communications-Based Train Control (CBTC); Automatic Train Supervision (ATS). Systems engineering. Published February 2023.

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Covers the subject of the interface between the signalling system and a human operator in a signal box or control centre. The technology of these systems varies from mechanical levers and control panels with switches or buttons to computer workstations, but they all provide controls, which enable the operator to manage train movements and indications, which provide the operator with information about the status of the signalling equipment and position of trains. Published in September 2020

Link to article is here

Part 1

Covers: What are points and why do railways need them? The basic design of points. Operational hazards associated with points. The role of signalling in point operation. Point operating mechanisms (manually and power operated). Checking that points are correctly positioned (detection). Locking the points in position. Published February 2022

Link to article is here

Part 2

Explores some of the additional features and functions associated with points. Topics covered include: Electrical power for moving points. Moving power-operated points under failure conditions. Time of operation of points. Trailable points. Supplementary operating mechanisms (back-drives; supplementary detectors). Swing nose crossings. Fixed diamond, switch diamond and slip switch crossings. Track circuit insulation in points. The effects of temperature on points and points for avoiding collisions (catch points, trap points, derailers). Published March 2022

Link to article is here

This article looks at three related subject areas, namely: scheduled maintenance; fault- finding; and how Remote Condition Monitoring (RCM) can assist with both of these. They are considered specifically in relation to points but they are applicable to other sub-systems as well. This article looks at: Scheduled (preventive) maintenance. Corrective maintenance. Maintenance standards. Permanent Way (track) maintenance. Signalling maintenance and Optimisation by use of Remote Condition Monitoring (RCM). Published in May 2022

Link to article is here

The article covers all the key issues related to technical safety management in the railway domain, including: Definitions of terms (hazard, risk, harm, cause, safety measure). Risk reduction (eliminate; substitute; engineering; administrative controls; personal protection; ALARP and similar principles). Safety benefits and costs. Defence in depth (error avoidance; error detection; fault avoidance; fault detection; fault tolerance). Hazard identification and analysis techniques and causes v. hazards. Published in June 2020

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This B2B article provides an introduction to RAMS (Reliability, Availability, Maintainability, Safety) and how good availability is dependent on good equipment reliability and maintainability, which in turn is essential to deliver a safety function. Published January 2023

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Francis explains the concept of the Safety Case, a fundamental element of project assurance for projects in many parts of the world. International railway Standards
EN 50126, 50128 and 50129. Quality Management; Safety Management; Technical Safety Report. Published November 2024

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This article explains what "SIL" (Safety Integrity Level) is all about, and how it applies to railway signalling. Safety Integrity Level (SIL) is an indicator of the relative risk reduction provided by a safety function in a device. A SIL number between 1 and 4 (SIL 1 being the lowest level of safety protection and SIL 4 the highest) is used to describe the degree of safety protection required and the safety reliability of a system which is needed to achieve that protection. It should be noted that safety reliability is not the same as performance reliability, as this back-to-basics article explains. Published October 2022

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This article looks at lineside railway signals. Signals are referred to frequently in other "back to basics" articles but without exploring the subject in detail. Movement authorities; verbal instructions; lineside signals; cab signalling. Interpreting signal information. Positioning of signals. Signal design. Maintenance considerations. Low speed movements. Published November 2023

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Part 1 - Networks

Covers the subject of railway telecoms. Communication is essential to all businesses including railways and without telecoms services trains would not run effectively. It is possible for trains to move without signalling, but communications are necessary for efficient operation. Railway telecoms covers voice, data and radio for rail operations, rail business, and passenger use. It can also cover commercial telecoms services for some railways. Published in October 2020

Link to article is here

Part 2 - Telecoms for passenger use

Went on to cover. Public address systems (PA). Voice alarm systems. Passenger information systems (PIS/ CIS). Closed Circuit Television Systems (CCTV), Clocks and Internet on trains. Published in November 2020

Link to article is here

This article was actually the first B2B written and was based on a simpler article Paul had previously published in another publication, which David suggested would be of interest to IRSE Members. This B2B looks at the essentials of train detection, including: Fundamentals of train detection (design principles). Track circuits – basic operation and types (DC, AC, audio frequency, coded). Rust films and contaminants. Train/track circuit compatibility issues. Insulation and bonding, including insulated rail joints (IRJs) Broken rail detection. Compatibility of track circuits with AC/DC electrification. Axles counters. Cab signalling and trainborne train detection. GNSS (satellite navigation) and PTC (Positive Train Control). Remote condition monitoring of train detection systems is also covered. Published in December 2019

Link to article is here

This B2B examines the various types of train protection and how they affect the performance of the railway. It provides a generalised review of the development of protection systems, outlining the key requirements with examples of systems from the UK and other countries. The article categorises systems as those that provide protection against overrun (Signal Passed At Danger – SPAD) and those that are primarily warning systems to alert the driver to the need to reduce speed or stop. Systems covered include ATP as in ERTMS/ETCS/CBTC, AWS, TPWS, train stops, and PTC. Continuous and intermittent update ATP systems are also considered. Published in July 2020.

Link to article is here