Listen To Your Tracks, Trains And Infrastructure

Frauscher Sensor Technology is a leading supplier of axle counters and wheel detection systems based on inductive sensor technology participated in the IHHA conference again this year. Together with Gear Rail, its partner for Sub-Saharan Africa, the company seized the opportunity to introduce its latest innovation, the Frauscher Tracking Solutions FTS to the heavy haul experts on-site. This new product line is based on Distributed Acoustic Sensing (DAS) and has the potential to provide the industry with all new and yet known but significantly optimised applications, especially when it comes to asset condition monitoring.

Distributed Acoustic Sensing (DAS): how it works

When sending a light pulse into a glass fibre, millions of minor changes (“scatter sites”) each scatter a small portion of that light pulse back towards its emission site. The reflected component of this scattered light is called “backscatter”. DAS uses this effect by sending a light pulse down the fibre strand and detecting the backscatter, which also is changed by sound waves and vibrations along the fibre. With evaluating these changes of the backscatter, the whole fibre optic cable turns into a continuous sensor that works like a string of virtual microphones.

As the light pulse and backscatter are travelling at the speed of light, changes detected in the backscatter caused by various sound sources can be translated into acoustic signatures. By developing appropriate algorithms, it is possible to connect these signatures to specific events. Using this method, it is possible to detect people walking, trains moving, changes in an asset’s condition, and more, as all of these create certain amounts and patterns of acoustic energy.

It was apparent during initial test installations that DAS provided a wide range of benefits. However, just like any other sensing technology, it has a specific set of challenges to overcome. In its current form, DAS does not robustly identify which track a train is travelling along. While the cable senses all the trains and their movements on all the tracks, it still requires a secondary input to corroborate which track the acoustic signature is associated with.

Listen To Your Tracks,  Trains And Infrastructure
Frauscher Wheel Sensor RSR180.

Frauscher Tracking Solutions FTS

Frauscher Sensor Technology has developed a set of railway specific DAS solutions, called Frauscher Tracking Solutions FTS, which integrate DAS with proven axle counters and wheel sensors. This allows overcoming the constraints described above and enables DAS to be applied comprehensively to a double track line.

When used on a stand-alone basis, FTS provides real-time information of a train’s position, speed, acceleration, length and more. Furthermore, it can detect activities such as people walking and thereby fulfil several security applications. When combined with wheel detection systems, an axle counter such as the Frauscher Advanced Counter FAdC takes care of fail-safe track vacancy detection up to SIL 4, while FTS generates additional information that can be used to optimise train movements.

Listen To Your Tracks,  Trains And Infrastructure
Frauscher Advanced Counter FAdC.

Asset condition monitoring based on FTS

Whilst conducting tests to further develop the capabilities of FTS for train tracking and security applications, a range of options to use this new solution for asset condition monitoring were also identified. 

Broken rail detection

Currently, track circuits provide the most commonly used method for detecting broken rails, although they fail to accurately locate the broken rail within a block section. Using FTS it is possible to detect broken rails under a passing train anywhere along a monitored track in an economic way, with an accuracy of up to 10 metres. Detection and classification is possible in real-time and the operator is made aware of the broken rail immediately. 

Listen To Your Tracks,  Trains And Infrastructure
Broken rails can be detected using Frauscher Tracking Solutions FTS.

Flat wheel detection

A similar process was applied to enable flat wheel detection. Whereas currently a Wheel Impact Load Detection (WILD) device is used at discrete fixed locations to detect flat wheels, FTS has the capability to identify flat wheels along the entire length of the sensing fibre. In the future, it will even be possible to classify their severity across the whole network.

Rock fall detection

Rocks falling on tracks generate a certain degree of acoustic energy, so FTS can also detect this kind of environmental influence. As with other applications, it is possible to localise the event to the closest 10 metre section of fibre significantly reducing the downtime associated with finding the source by ground staff. Recognising such an event enables railway operators to warn trains, improving safety and traffic management. Radio transmission even allows appropriate information to be sent directly to the train engineer. By conducting fine adjustments, even the moving paths of rolling rocks are detectable.

Outlook: potential to prevent and predict

In addition to the proven capabilities of DAS to track trains in real time, detect flat wheels and broken rails, alert for personnel intrusion and rock fall, it carries the clear potential to deliver a dynamic view and real-time situational awareness of infrastructure health. This in turn, allows for immediate, short and long-term preventive and predictive maintenance actions to be instigated.

The asset condition monitoring data already generated by FTS can support the development of smart maintenance strategies based on prevention and prediction. Thereby, FTS contributes to reduce the overall cost of running expensive maintenance assets whilst at the same time improving the ability of an operator to increase operational service. “These possibilities will be especially interesting for operators from the heavy haul industry, as damages and wear at neuralgic points, such as track joints, are more likely to occur on infrastructures which are frequently used by heavy trains. Against that background we are sure that FTS will provide our customers with interesting options in addition to Frauscher’s existing portfolio of innovative axle counters and absolutely precise wheel detection systems”, says Roelf Alberts, CEO at Gear Rail.


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