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Performance challenges facing railway signalling and telecoms – what does good look like?

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Guest writer: Shelley Robertson, Comtest Wireless

Around the world, rail organisations are working hard to increase capacity and operate faster, safer trains more efficiently.

In the UK, Network Rail has allocated £180 million as part of CP6 (Control Period 6, 2019-2024), towards its Digital Railway Programme (DRP). The focus is on supporting improvements to train performance by tackling three fundamental problems: providing greater capacity, improving service reliability and reducing signalling system renewal costs. It also includes National enabling projects such as telecoms system upgrades.

Furthermore, as over half of Britain’s analogue signalling systems, with lineside ‘traffic lights’ controlling trains, needs be replaced within the next 15 years, this is planned to be addressed in CP7 (2024-2029) onwards.

Let’s examine some key challenges faced by those responsible for rail telecom and signalling systems performance and operations, and propose ‘what good looks like’ to mitigate them today and in the years ahead.

The digital rail environment

Digital rail relies on the smooth and continuous operation of rail telecommunications networks (such as GSM-R), signalling networks and interlocking systems.

 Under full Level 2 ETCS (European Train Control System), train movement authorities and other signalling aspects are monitored continually by the radio-block centre using trackside-derived information and transmitted to the vehicle continuously via the telecom network (such as GSM-R) together with speed information and route data. Balises are passive positioning beacons or “electronic milestones”.

Performance challenges

These are just some errors that can occur:

  • GSM-R coverage, handover, interference, transmission errors, congestion, authentication failures and equipment malfunctions;
  • Signalling, MSC-RBC communication errors, RBC- EVC protocol stack issues, software bugs in RBC firmware, RBC-RBC interoperability problems;
  • Interlocking misreading, misalignments, switch issues, track occupation issues;
  • EVC malfunctioning, wrong identification, drivers’ mistakes.

With such a diverse range of potential issues, finding the root cause of a problem can be time consuming and frustrating for signalling and telecoms engineers, and expensive for the train operators or infrastructure providers when it comes to unplanned maintenance and penalty payments.

Challenge 1 – “The environment is complex”

Rail telecoms, signalling and interlocking systems are very different technologies and are typically managed by different departments.

These systems must work perfectly together 24/7, as well as adhere to stringent industry operability requirements and standards. When something goes wrong and the train does not receive its next ‘movement authority’, it cannot proceed. This can result in frustrating delays, a poor passenger experience and incur penalties – all of which are compounded if more trains further up the line are then also delayed.

Checking performance for each system is challenging, as there is so much data to manage and synchronise, in order to try to identify the issue. Whilst much work can be done to use simulations and lab environments for testing, it is impossible to test everything until it is in the field.

What does good look like?

Vast numbers of data packets are sent between the train and the signalling and interlocking in real-time. When all the data from the rail telecoms network, signalling and interlocking is collected, synchronised and displayed in a single place, it provides a significantly simplified view of the train run and diagnostics, as well as complete visibility of systems’ performance from start to finish.

Challenge 2 – “Data silos make troubleshooting hard work”

Typically, rail telecoms, signalling and interlocking have their own separate combinations of vendors and monitoring tools – even on the same line.

“There are over 80 individual sequences required just to start a single train ‘mission’ under ERTMS.  If just one is missed or is not transmitted correctly, the train cannot proceed.”

When a train stops, manually scanning multiple logs makes troubleshooting very time consuming, even for the most experienced of engineers. It’s even more challenging when the data is missing or unable to be correlated.

What does good look like?

‘Good’ is the ability to have automated alerts, making it easier to see what went wrong, when and where. With each sequence of events synchronised as tables, charts and maps, it’s much easier to pinpoint telecoms, signalling or interlocking failures more quickly. This enables the team to dedicate their time and expertise to identifying the ‘why’ and fixing the problem.

Challenge 3 – “We shouldn’t rely on a ‘fix on failure’ approach” 

Unplanned maintenance increases costs and often means frustrating changes to engineering work schedules.

Planned maintenance costs less than fixing something in emergency situation and should prevent a failure in live circulation.

Here are three example cases of challenges with asset management.

Interlocking failure

When the interlocking patterns are not properly developed, the train goes into an Emergency Stop. That may happen because of switch failure, ice, faulty sensors, etc. Collecting a consistent amount of data allows the use the statistics to understand which switches (track points) have more failures and why, so we can plan proactive maintenance and prevent unexpected failures.

Balise failure

A balise is an electronic beacon or transponder placed between the rails of a railway as part of an automatic train protection. Balises are often set in group of 2-3 units, with two consecutive groups of balises as a redundancy measure.

When a balise fails, the ETCS message relays that there is a balise issue but not if it involves a single balise or more than one. If this had been the only operational balise in the set, its failure means circulation paralysis. The train cannot trigger or send the position report and cannot reset the odometer error for an emergency stop. Needless to say, this failure would cause big delays to the entire circulation from that line. If we have the right information about which balise is faulty, this would allow us to prioritise and plan maintenance.

Radio degradation

Nothing lasts forever, including rail telecoms and wayside signalling equipment. When you start seeing a degradation in the radio pattern, you can plan proactive maintenance, such as checking radio network coverage in case of BTS failure.

This can also help with system interference issues, such as radio problems caused by a third-party.

What does good look like?

Using a single analytics platform not only provides greater visibility of real-time systems performance, it also enables rail telecoms and signalling engineers to build up a comprehensive database of information about their asset performance. This makes it easier to spot degradation trends and faulty equipment, helping them to be better placed to predict and plan maintenance, rather than a costlier ‘fix on failure’ approach.

A Combined Approach to Monitoring & Troubleshooting

When data is collected on-board in real-time and combined into a single platform, rail telecoms and signalling operatives and managers can easily monitor, analyse and troubleshoot rail telecoms and signalling systems performance.

About Comtest Wireless

Comtest Wireless provides world-class on-board & wayside test, measurement and monitoring solutions for rail telecoms, signalling and interlocking systems.

Readers are welcome to attend a free Comtest Wireless UK workshop in London on 21st April. To learn more or book a place, please visit https://www.comtestwireless.eu/events/comtest-wireless-to-host-uk-workshop-all-welcome/ or email [email protected]

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