Running on glass-fibre
Current developments show that glass-fibre technologies will significantly impact the future of the railway industry. Kevin Tribble, FTS Product Management at Frauscher, casts an eye to the future of corresponding train detection solutions.
Train detection systems are essentially caught between the conflicting priorities of safety requirements, performance expectations and costeffectiveness. Fulfilling all three criteria entirely at the same time, is extremely difficult; after all, the three factors depend on very different parameters. Glassfibre technologies such as Distributed Acoustic Sensing (DAS) however offer major potential when it comes to the key aspects of each of these areas. This is evident from the experiences gained by the railway industry from this approach over the past few years.
The potential is extremely high when corresponding train tracking solutions are used. Like other approaches, they too enable rolling stock to be detected in real-time and across vast sections of the track. However, only a minimal track infrastructure is required. There is virtually no need for any retrofitting to trains as well.
DAS offers huge potential
A mere glance at the technical bases shows that little hardware is needed for train detection with DAS: as a trackside infrastructure, it simply needs a single glass-fibre. This is then charged with laser pulses. By evaluating the changes in the reflection of these pulses, the fibre is converted into a sensor that runs along the track and is capable of detecting sound waves and vibrations. Due to its technical properties, DAS thus enables moving objects to be reliably tracked over long distances.
Train tracking is on track!
Real-time train tracking: When detecting trains using DAS-based systems, such as the Frauscher Tracking Solutions FTS, users can generate various kinds of useful information.
The Frauscher Tracking Solutions FTS presented by Frauscher in 2016 are now being used around the globe in different applications. This has allowed the development team to continually gain new insights into the properties, strengths and potential of this technology in the field of train detection.
Installations have been realised in countries with a broad range of conditions; besides Germany and Austria, these nations include France, Australia, China, Brazil, India, the USA, Belarus, Ukraine, Turkey and the UK. The wide range of applications forms a basis for the diverse testing of the properties of the Frauscher Tracking Solutions FTS in the field of train detection.
Take up position
Practical experience has also shown that certain installation parameters can have a positive impact on the accuracy of DAS-based applications in train detection. This includes the position of the cable and its distance from the track as well as the type of installation itself – in other words, whether the cable is buried, is in a trough, or affixed to the wall of a tunnel. Previous installations have demonstrated that cables laid in concrete troughs or directly in the ground are especially well-suited to detecting different influences. Cables installed above the ground however are often affected by additional factors such as wind, rain or hail and therefore register a higher “ambient noise level”. The ideal type of installation ultimately always depends on the requirements which the application must satisfy.
In addition to this, it is vital to calibrate the system with precise geo-referencing data. Information about the position of the glass-fibres is hereby linked with GPS or route data which, during operation, gives some indication of the precise routing of the fibre-optic cable along the line being monitored. This routing may under certain circumstances deviate from the position of the track – in order to bypass an obstacle, for instance.
Digitisation opens up possibilities
The lines equipped with test installations are already benefiting from the data from the FTS system. Besides information for the actual traffic control system, i.e. the current position of a track vehicle, its speed, direction of travel and length, it is also possible to generate information for other systems. This includes the estimated time of arrival at a defined point, for example a railway station, in order to provide platform announcements or train timetables. Level crossings which are currently being activated and deactivated by axle counters, can in future be controlled with even greater precision by implementing the additional information.
The examples show how important the interoperability of data and systems is. By having a combination at a fundamental level, exact data can already be output in the first instance. This can then be linked with further information.
In order to exhaust the best possibilities this technology has to offer, it is essential to have logical links between the various data. It is also important to include approaches such as cloud computing and machine learning in the relevant concepts.
Train detection solutions, which like FTS, are based on glass-fibre optics, will in future play an ever-increasing role in the railway industry. Recent years have already demonstrated a broad field of application. From past experience, Frauscher has already been able to develop a strategy which is based both on a stand-alone solution and on combined systems using tried-and-tested components.
This is significant for two reasons. Firstly, it offers the possibility of a gradual introduction, including in safety-critical areas. Secondly, by combining various detection technologies, it is possible to generate added-value data of considerable relevance.
In order to implement the relevant applications successfully, rapid progress must be made with digitisation strategies. After all, it is these strategies that will allow a more efficient use of data in the sense of conversion into concrete and useful information.
Yet this necessity applies not only to new solutions. If a combined approach with axle counters and wheel detection systems is to continue to be pushed – especially in safetyrelevant areas – then these components too must follow the path of digitisation in order to be able to provide data via the relevant channels and with maximum efficiency.
Fibre-optic cables are often already in place along a track and can be used to install FTS.
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