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Forensic engineering

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Crewe, in South Cheshire, is known for quality engineering, being the home of Bentley cars and the world famous locomotive works. It will be a major hub for the planned HS2 and is also famous for a football team that punches above its weight. However, just a stone’s throw away from the proposed hub and the Crewe Alexandra FC Gresty Road ground, is the home of one of rail’s best-kept secrets.

Based in an office built in 1903/4 by the London North Western Railway for the Electrical Signal and Telephone Department is the Atkins Technical Investigation Centre (TIC). The TIC provides a forensic engineering service to rail – basically it’s a team of specialist engineers who investigate equipment failures in a laboratory setting in order to identify why an issue has arisen.

The TIC covers most rail engineering disciplines and provides an independent investigation service for failed assets and incidents such as level crossing accidents, signalling wrong-side failures and OHLE de-wirements. Its principal focus is on safety-critical and safety-related failures, but the scope also includes significant equipment failures that have caused major disruption or repeat failures, where investigation by technical specialists might help to get to the root cause.

The key to the TIC process is not to have any preconceived ideas of what the cause of a failure may be, but to investigate in a systematic manner and to eliminate all the possibilities using engineering principles in a laboratory setting.

Once the root cause is identified, the TIC will make recommendations to reduce the likelihood of failure. This could include equipment modification, a special inspection notice on all similar assets in the network, or an amendment to a maintenance specification.

Customers and suppliers

The TIC’s customers include Network Rail, train operating companies, metros, tram systems, London Underground, overseas rail (one recent enquiry was from Singapore involving a relay that caught fire), British Transport Police and the Rail Accident Investigation Branch. The TIC has the majority of skills and processes required, but it also uses specialist test houses for metallurgical investigation support and vibration testing.

They also have access to the rest of the Atkins organisation. For example, a level crossing ‘Another Train Coming’ audio device was sent for investigation as it was believed to be announcing in Chinese. With the help of the Atkins project office based in Beijing China, the TIC was quickly able to identify that it was Chinese. The investigation also found that the audio device could be recorded locally with any message.

The TIC also has access to the Atkins design office which is able to support an investigation with detailed circuit analysis or data analysis for computer-based systems.

Typical equipment sent to the TIC for investigation includes: relays, cables, signals, train detection equipment, Automatic Warning System (AWS) and Train Protection and Warning System (TPWS) items and, more recently, the first European Train Control System (ETCS) balise requiring investigation. The cause of the failure was attributed to ingress of salt water.

The scope of the assets investigated has been widened recently to include electrification assets and the Atkins team can be called upon to determine the cause of a de-wirement.

If a fault is caused by a manufacturing problem, the TIC invites the manufacturer (if still available) to witness the tests, provide technical information and offer comments on the report before it goes to the client. Such invitations are standard whenever a manufacturer’s fault is identified and demonstrates Atkins’ independence.

In a recent case, the manufacturer of the faulty signal accepted the invitation and, after witnessing the testing and intermittent fault, voluntarily agreed to alter its manufacturing, quality and maintenance procedures to prevent the failure occurring again.

People and process

The 20 or so strong team at the TIC is made up of engineers with considerable forensic investigation expertise, covering predominantly electrical and electronic applications, but also including mechanical, hydraulic, pneumatic and material science domains.

Although these skills are used by Atkins to unravel rail-related safety / performance issues, the know-how and processes can be applied to virtually anything. Electrical and electronic equipment work in the same way, whether on an oil rig, train or submarine. The principles remain the same, so in theory the TIC can test/investigate just about anything that uses electricity and if the specification is available.

Once a suspected faulty item is received into the TIC it is placed in triage. The item will be assessed for the competency required to carry out the investigation and the creation of a detailed investigation plan before any testing commences.

The testing is carried out in phases: visual examination, non-destructive testing and finally destructive testing, with a review of the findings at the end of each phase. All test parameters are recorded meticulously. While competency and quality processes are now a requirement for most successful companies, such systems have been in place within the TIC for a very long time.

Evidence recording is extremely important as the engineers may be called to provide evidence in a court of law and it is invaluable in supporting the investigation of other similar failures. The TIC has records going back over a hundred years, some of which make fascinating reading including one on the use of radio to communicate with a train in the 1920s!

The TIC is one of very few rail teams in the country to have the necessary Institution of Railway Signal Engineers licences to carry out this often- sensitive and confidential work, and it’s not uncommon for the centre’s findings and recommendations to influence manufacturing practice, safety standards and maintenance specifications, within the rail industry.

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The TIC is located adjacent to the Atkins signalling project office and this helps the TIC engineers maintain their competency with site visits to carry out new works correlation, as well as attending training courses on new systems, so that they are ready when new items are sent for investigation. They also support projects with teams to assist, for example, the commissioning of new complex track circuit layouts.

Investigation examples

A signal kept reverting to and staying at red – a situation which caused train delays and numerous site visits by the local maintainer. During the investigation, the TIC not only identified an intermittent fault that caused the signal to revert to red but also discovered that the interaction between the signal modules was not readily understood by the maintainer, meaning that its repeated attempts to get to the bottom of the problem were fruitless. The intermittent fault was caused by a manufacturing problem.

A box of fire damaged batteries, from a mechanical signal box was sent to the TIC for investigation. After carrying out various tests, it was determined that this new type of battery, produced by a particular manufacturer, delivered a much higher current than the older types.

They also came in a range of different sizes and capacities. If the different sizes are mixed together they can overheat and, if they are not wired up and positioned carefully, a short circuit causing sparks can occur, igniting flammable material nearby.

Although this explanation does sound relatively straightforward, it doesn’t tell the whole story. Before this conclusion was reached the TIC carried out a number of tests, taking care not to prematurely dismiss any possibilities. Did the batteries have any technical limitations? Did vibrations from passing trains move them around? To what extent was the fire caused by human error?

The TIC has been involved with a number of major incidents, such as Ladbroke Grove, Grayrigg and Potters Bar, as the licensed independent engineering investigation team. This independence from maintainers, infrastructure controllers, designers, and equipment suppliers is an important point.

One area the TIC can be of further use to the rail industry is with the acceptance process for new products. It is not unknown for new items of equipment to be installed on the railway only to fail some months later, with safety or performance implications. The TIC may only then be involved to identify the root cause of the failure. Often, the harsh environment of the railway – physical and electrical – can give rise to problems that even the most careful planning and design cannot foresee. The TIC can bring its experience to the process, looking at lessons learnt from similar applications and using simulations to mimic real life at the trackside where equipment is expected to perform reliably for up to 30 years. Getting it right at the outset can prove to be a good investment, saving failures, product recalls and operational delays downstream.

Other services

The TIC also supports projects with immunisation testing and analysis. This involves instrumenting and analysing the area and systems being changed or, for example a new type of rolling stock. The railway system with its legacy products is very difficult to model and sometimes the only way is to go out and measure everything in a systematic and recordable manner.

A recent example for Thameslink was a points installation on slab track and a requirement to check that the machine was holding fast. The TIC came up with a network of void meters, glued to the rail and slab, and connected back to a recording device. This verified that there was no movement of the machine. This was undertaken at the same time as checking for both AC and DC interference with the interface with LUL.

Support is provided to the signalling projects division of Atkins. This includes FRACAS (Failure Reporting And Corrective Action System) and DRACAS (Defect Reporting And Corrective Action System) modelling for major projects. The TIC has also been involved with type approval for the new generation of Atkins computer-based signalling, with both AC and DC testing of the interlocking and level crossing controllers in areas of high electrical interference.

The future

The TIC has all the skills and processes to support other industries and this may include the emerging industry of intelligent transport, autonomous cars and highway monitoring. Motorways are currently monitored by CCTV but, in the future, this may be undertaken by similar technology as RADAR and LiDAR used in obstacle detection at level crossings. Who better to investigate forensically when it fails?

Paul Darlington CEng FIET FIRSE
Paul Darlington CEng FIET FIRSEhttp://therailengineer.com

Signalling and telecommunications, cyber security, level crossings

Paul Darlington joined British Rail as a trainee telecoms technician in September 1975. He became an instructor in telecommunications and moved to the telecoms project office in Birmingham, where he was involved in designing customer information systems and radio schemes. By the time of privatisation, he was a project engineer with BR Telecommunications Ltd, responsible for the implementation of telecommunication schemes included Merseyrail IECC resignalling.

With the inception of Railtrack, Paul moved to Manchester as the telecoms engineer for the North West. He was, for a time, the engineering manager responsible for coordinating all the multi-functional engineering disciplines in the North West Zone.

His next role was head of telecommunications for Network Rail in London, where the foundations for Network Rail Telecoms and the IP network now known as FTNx were put in place. He then moved back to Manchester as the signalling route asset manager for LNW North and led the control period 5 signalling renewals planning. He also continued as chair of the safety review panel for the national GSM-R programme.

After a 37-year career in the rail industry, Paul retired in October 2012 and, as well as writing for Rail Engineer, is the managing editor of IRSE News.


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