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pdf.png What they didn't tell you at university ... or did they? HOT

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John Aitken BE SMIEEE MIRSE

Aitken & Partners

Presented at IRSE Australasia Conference - Adelaide - 8 April 2015

Simplifying assumptions are a key to understanding many problems and can be very helpful. Thin, inextensible strings and ideal capacitors make for simple analysis but neither is available for purchase, so their practical usefulness is limited.
Sometimes, simplifying assumptions conceal an underlying problem or distort our understanding.

This tutorial paper discusses some situations where assumptions may lead to undesirable outcomes and provides some gentle reminders to exercise caution and be thorough in design, implementation and testing.



pdf.png Drive a mile In my seat: Signal Design from a Systems Perspective HOT

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Anjum Naweed BSc MSc PhD, Central Queensland University

John Aitken BE MIRSE SMIEEE, Aitken & Partners

Presented at IRSE Australasia Technical Meeting: Newcastle 25 July 2014

Train drivers navigate conventionally designed railways using a keen awareness of their routes and by calculating likelihood predictions of future states. These processes have traditionally followed a model of signal-to-signal based running, which comprises the awareness of their static (location-based) and dynamic (aspect-related) properties.

This paper reports findings from a study that examined the socio-cultural and technical ties between the signal and the driver in the context of SPAD risk management. It provides examples of how signal aspects are being interpreted on Australasian railways, how operational pressures are altering the driver-signal dynamic, and how the meaning of the caution aspect has evolved in today’s dynamic and productivity oriented rail environment.

The paper seeks to describe the train drivers’ experience of interpreting and responding to railway signals, so that the signal engineering community may better understand the implications of introducing new variables and schemes into their signal design language.

 



pdf.png In all normal and reasonably foreseeable abnormal situations .... HOT

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John Aitken BE MIRSE SMIEEE Aitken & Partners

“New rolling stock or electrical/electronic equipment to be used in rolling stock modifications must be designed, built and maintained with regard to EMC in order that they operate safely throughout their operational life. This applies to all normal and reasonably foreseeable abnormal situations, including failures.”

Such a statement is easily made but compliance is not readily demonstrated, particularly when there is little or no definition of what might make something electromagnetically compatible (EMC). Signalling systems are generally poorly defined from an EMC viewpoint, so foreseeing abnormal situations can require considerable insight into the design and failure modes of the signalling systems.

This paper discusses what is normal and then considers some of the failure modes and vulnerable areas in train detection systems; the threats posed by traction systems and some of the foreseeable abnormal situations.



pdf.png Train Position Determination HOT

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Jeanette Aitken BE MEngSc

Graduate Engineer, Aitken & Partners

IRSE Australasia Technical Convention, Sydney, 28 November 2003

This paper describes a method of improving the determination of train positions that is particularly applicable in areas where track circuits are not available. The method uses multiple GPS antennas for position and heading determination.

One of the key problems with standard GPS solutions is the difficulty in resolving the track that the train has taken at a junction. Parallel tracks may lie within the resolution ambiguity of standard GPS and DGPS position measurements. We propose that attitude determination be used to determine the path that the train has taken at a track junction.  The document then explains the equipment and methods that were considered best for solving these problems.



pdf.png GSM-R - Advanced, Available, Approved and Applicable: Part 3 - Applicable HOT

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John Aitken, Aitken & Partners

Martin Lehrbaum, Nortel Networks

Glyn Owen, Siemens

Presented at AusRAIL Plus 2003, Sydney 17 November 2003

GSM-R, the railway extension of GSM telephony, has been designed specifically to satisfy railway radio communication requirements. In this three-part paper we describe the Advanced features of GSM-R that set it apart as a railway system and demonstrate that it is available technology, ready for use today. We explain how GSM-R has been approved by international standards organisations and has a Notified Body process for type and system approval. Finally, we show that GSM-R is applicable to Australia, providing an effective solution to many of the communication problems of Australian railways.

Part 3 discusses the applicability of GSM-R for Australian railways. The general requirements of Australian railways are reviewed and compared with the facilities and functions offered by GSM-R. We demonstrate the applicability of GSM-R through two case studies.



pdf.png Australia Wide Communications System for Railway Operators HOT

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John Aitken BE MIEEE AMIRSE

Director, Aitken & Partners

Presented at IRSE Australasia Technical Convention, Adelaide 14 March 2003

Australia has a sad history of incompatibility in railway radio communications. There is no standard for radio communications on the standard gauge track. Some states have incompatible radio systems on different track gauges; one has incompatible radio systems on the standard gauge track. The situation looks likely to continue for many years, imposing a substantial cost on each rail operator.
Incompatibility has a further cost to the community, as the McInerney inquiry into the Glenbrook rail accident and the Hexham inquiry show. The Hexham inquiry demonstrates that radio system design can affect the susceptibility of a rail network to human error. Ergonomics and equipment failure are regularly considered but there is rarely an analysis of the effects and consequences of human error in the radio communications system design. Some improvement could be gained from expanded Codes of Practice, identifying risks and hazards for consideration at the design and testing stages.
Over the last twenty years the mainland railways have moved towards a common frequency band for radio communications. Despite this, sufficient proprietary quirks have been implemented into the radio systems to ensure that no single radio can cover all systems. Locomotives are equipped with up to seven different radios to operate through the Defined Interstate Railway Network. Recent changes in the cellular telephone market have made the use of GSM-R feasible in Australia. GSM-R could replace incompatible train radio systems in higher traffic areas with internationally standardised equipment. GSM-R is not economical for low traffic areas but can be integrated with existing mobile radio and satellite telephone networks.

The paper concludes with a description of an integrated train radio system that was fitted to the CRT CargoSprinter. This is an example of a screen-based radio system that presents a consistent interface to the driver despite variations in radio communication technology along the track.



pdf.png Name: GSM-R - Advanced, Available, Approved and Applicable: Part 1 - Advanced HOT

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John Aitken, Aitken & Partners

Martin Lehrbaum, Nortel Networks

Glyn Owen, Siemens

Presented at AusRAIL Plus 2003, Sydney 17 November 2003

GSM-R, the railway extension of GSM telephony, has been designed specifically to satisfy railway radio communication requirements. In this three-part paper we describe the Advanced features of GSM-R that set it apart as a railway system and demonstrate that it is available technology, ready for use today. We explain how GSM-R has been approved by international standards organisations and has a Notified Body process for type and system approval. Finally, we show that GSM-R is applicable to Australia, providing an effective solution to many of the communication problems of Australian railways. Part 1 outlines the advanced and railway specific features of GSM-R.



pdf.png Development of a Radio Propagation Model for an Open Cut Mine HOT

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John Aitken BE

Director, Aitken & Partners

Presented at IREECON 20th International Electronics Convention, Melbourne, 1985

A radio propagation model developed to analyse mobile radio coverage in an open cut mine is described.  The model is based on the Geometric Theory of Diffraction, with extensions for dielectric surfaces.

In most propagation modelling problems the terrain can be represented with a reasonable degree of accuracy by some combination of three shapes.  The shape most commonly used is the simple knife edge which gives surprisingly good estimates when applied to isolated obstacles.

The other shapes generally used are the cylinder for mountains and rolling hills and the sphere for certain undulating terrain and plains.

The terrain of an open cut mine is, however, quite different from a natural surface.  Instead of clear peakes and rolling hills the sides of the mine are cut into benches, giving jagged discontinuities.



pdf.png Communication in Emergency - Success or Failure? HOT

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John Aitken BE MIRSE MIEEE

Director, Aitken & Partners

Presented at IRSE Australasia AGM, Adelaide, 15 March 2013

Emergency implies urgency. Not just urgency but abnormality. We have no difficulty dealing with what is normal, routine. However, when an emergency arises our systems are often found wanting.
Communication systems are not just collections of technology but are interactions between people, with technology interposed. The systems are inherently complex and over time they change: through changes in people, in organisations and in technology. The change may be subtle, an unnoticed drift from safe operation. Sometimes the change is only evident when an urgent, abnormal situation arises.

Incidents from around the world form the basis of this paper. In each of these incidents the communication system has failed those who depended on it in a time or emergency. In few of these incidents did the technology require repair: rather, a defect in the complex system of communication was exposed.

Myth and legend are inadequate substitutes for thorough training, system analysis and testing. Too often the consequence has been fatalities. This paper seeks to address some of the causes and suggest solutions.



pdf.png Error Tolerant Communication Systems HOT

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John Aitken BE MIEEE AMIRSE

Director, Aitken & Partners

Presented at Rail Safety Conference, Sydney 16 February 2004

Railway safeworking systems are based on rules. These rules may incorporate some provision for error: for example the maintaining a headway between trains so that passing a signal at danger may not constitute an immediate risk of collision.
If the rules are obeyed and the train is run to timetable then there is no need for communication. Indeed, most railways have operated on the basis that communication is made only in exceptional circumstances and signal post telephones were invented in response to that assumption. Track circuits have been employed to control automatic signals but their operation and status was considered irrelevant to the signaller in some administrations. In earlier designs the signal post telephone was wired to a specific indicator in the signal box. The signaller knew with confidence that the driver of the train had not only stopped the train in order to use the telephone but had stopped it at a particular location. (The primary identification was the verbal statement by the driver of the location. The technology provided confirmation of the driver’s assertion.) Rules were written on the basis that this technology would continue to be used: when changes were made in technology and communication systems, the rules did not follow the changes. The communications system, which had previously provided a means of identifying errors in reported position, could now become a source of error and confusion. The rest, as they say, is history.



pdf.png GSM-R - Advanced, Available, Approved and Applicable: Part 2 - Available and Approved HOT

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John Aitken, Aitken & Partners

Martin Lehrbaum, Nortel Networks

Glyn Owen, Siemens

Presented at AusRAIL Plus 2003, Sydney 17 November 2003

GSM-R, the railway extension of GSM telephony, has been designed specifically to satisfy railway radio communication requirements. In this three-part paper we describe the Advanced features of GSM-R that set it apart as a railway system and demonstrate that it is available technology, ready for use today. We explain how GSM-R has been approved by international standards organisations and has a Notified Body process for type and system approval. Finally, we show that GSM-R is applicable to Australia, providing an effective solution to many of the communication problems of Australian railways.

Part 2 discusses the approval processes for GSM-R, its implementation to date and the availability of GSM-R systems.



pdf.png Does Centralised Control mean Centralised Communications? or Did Murphy Err? HOT

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John Aitken BE MIEEE AMIRSE

Director, Aitken & Partners

Presented at IRSE Australasia Technical Meeting, Sydney, 29 April 1990

Communications and signals engineers are known and respected for their thoroughness and careful planning.  They do not act on impulse but plan and design systems which are robust and have "fail-safe" operation and redundancy built in.

None the less, the unforseen does occur.  It may pass unnoticed , it may be identified as an incident or it may become a disaster.  The impact is nearly always determined by the timing.



pdf.png From Teletype to Megabyte - 150 Years of Railway Communications HOT

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John Aitken BE AMIRSE

Director, Aitken & Partners

Presented at IRSE Australasia AGM & Technical Convention, Sydney 18 March 2005

In October 1877 Bell published construction details of his telephone invention. A NSW Railway engineer, Mr Cracknell built a copy and transmitted words and music by telephone over the telegraph wire from West Maitland to Sydney in December 1877. It was an era of excitement and delight in engineering. Morse code had become a mature technology, voice systems were spreading and soon de Forest’s vacuum tube triode was to make amplification possible. Transmission systems were no longer limited in distance and the engineers had visions of linking the continent by telegraph and telephone.

The visions were gradually realised, though not without difficulty and dedication. The work practices of those days would not be considered now. New engineering problems were found, analysed and solved, as communication systems grew in complexity and expanse. Some of the problems were unique to railways and a few were unique to Australia (at that stage). From these beginnings railway communications have embraced analogue carrier telephony, radio, optical fibre and digital carrier systems for radio and cable. Mobile radio has been implemented for train control, security, maintenance and administration. Some of these developments are described and discussed in this paper.



pdf.png Public Carrier Communications Technologies and Strategies for Low Traffic Lines HOT

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John Aitken BE AMIRSE

Director, Aitken & Partners

Presented at IRSE Technical Convention, Singapore 24 October 2005

Australian railways have very low traffic densities on long routes. On many lines the traffic density does not justify a railway owned communication system so public carriers are used for both fixed and mobile communication. There is nothing new about using public carrier services in such situations – both fixed and mobile services been used for many years with substantial success. Soon the majority of Australian freight and country passenger services will use public carrier services for mobile communication.
Public carriers do not set out to provide reliable communications infrastructure for safety critical systems. They set out to optimise the profitability of their infrastructure. Can a railway rely on such a system for its operation? We review some technical and operational considerations.
Australian railways have resolved some of the technical and operational issues creatively. The most significant of these systems are described, along with the particular requirements of off-train communications.



pdf.png In case of emergency press Button "B" ... or is it "C"? HOT

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John Aitken BE MIEEE MIRSE

Director, Aitken & Partners

Presented at International Railway Safety Conference, London, 8 – 10 October 2012

Emergency implies urgency. Not just urgency but abnormality. We have no difficulty dealing with what is normal, routine. However, when an emergency arises our systems are often found wanting.
Communication systems are not just collections of technology but are interactions between people, with technology interposed. The systems are inherently complex and over time they change: through changes in people, in organisations and in technology. The change may be subtle, an unnoticed drift from safe operation. Sometimes the change is only evident when an urgent, abnormal situation arises.

Incidents from around the world form the basis of this paper. In each of these incidents the communication system has failed those who depended on it in a time or emergency. In few of these incidents did the technology require repair: rather, a defect in the complex system of communication was exposed.



pdf.png Outsourcing of Communications Networks HOT

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John Aitken BE MIEEE AMIRSE

Director, Aitken & Partners

Presented at IRSE Australasia Technical Meeting, Adelaide 19 July 1996

Outsourcing of services is a concept that has the virtues of political correctness and fashion.  It is certainly not a new concept but outsourcing has become a popular answer to all manner of corporate ills.  Its current significance is perhaps not unrelated to some fo the spectacular corporate failures of the 1980s when short term gains were the objective of many an entrpreneur.  The current reaction appears to be an emphasisi on "core business" activities, with those activities that are not considered essential to the core business being "outsourced".

Some would argue that commuincations are not core business for railways and that they should ahve been outsourced long ago. Others will argue that communicatiosn are the very life blood of a modern railway - as integral a part of the operation as the track, locomotives, rolling stock and signals.

In this paper we consider the role of communications in railway operations, the impact of historical developments, the impact of developing technology and the impact of legislation on railway communications. There are some areas where outsourcing is a natural and obvious step, some areas where outsourcing would achieve nothing and others where outsourcing has been in place for a long time.  The common characteristic is that they provide communications for trains that move on steel wheels on steel tracks.



pdf.png You can get lonely out there! HOT

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John Aitken BE MIEEE MIRSE

Director, Aitken & Partners

Presented at CORE (RTSA Conference on Railway Engineering), Darwin 20-23 June 2004

“You can get lonely out there!” sighed the track inspector. He had described working alone on some of the most remote rail track in Australia, travelling vast distances far from the highway. Radio often is his only contact with others.

Even when close to population centres railway lines can be remote or relatively inaccessible, with only train radio for communication. It would seem reasonable to expect that train radio systems would provide a robust and reliable link for people working in such environments.

Is this expectation realised? To test this we review a number of incidents and the performance of train radio and communication systems in these incidents. Some design decisions are discussed and their hidden features and risks are explored. It is evident that to not make a design decision is in fact to make a decision, but with an unpredictable outcome.

Incidents are usually the result of the failure of multiple defences against error: communication systems may be the last line of defence against disaster. As the last defence, the non-vital communication system can become very important. The communication system can be as important after the incident, for reporting and recovery.

Since incidents are relatively rare, it is essential that the communication system designer have a very comprehensive understanding of the requirements for all modes of operation. We advocate the adoption of international standards for railway communications. These standards benefit from the experience of many railways and are continually tested on a much larger scale than could ever be achieved in Australia alone.