Within all industries there is a constant drive to create better efficiencies, reduce health and safety risks whilst maintaining if not increasing the quality of output. This is certainly true with regards to infrastructure monitoring and without question the area that we are asked more questions about than any other is the monitoring of rail infrastructure.
With regards specifically to the monitoring of the rail tracks, the adoption of sensor based monitoring to reduce the number of boots on ballast, the risk of instrument theft, repair and maintenance costs and the enablement of remote monitoring has been met with a mixed response.
There has been a significant number of tiltmeters deployed to monitor the pitch and cant of tracks, but we continue to hear the same question over and over again relating to this. ”Are we able to accurately monitoring the track behaviour or are we simply monitoring the sleeper the sensors are attached to, which may not relate directly to the movement of the tracks themselves?“
The truth is, if we are simply mounting tiltmeters on to the sleepers, then we have a limited ability to accurately measure the behaviour of the tracks they are attached to. This is due to the design of the relationship between the sleeper and the tracks that intentionally allows for a degree of independent movement.
The sensor installed directly on to the sleeper may experience both pitch and roll without this being directly translated to the position of the tracks connected. Equally lateral movement in the Y axis or rotation in the Z axis may also relate solely to the sleeper and not to the attached tracks.
Monitoring the behaviour of individual sleepers is not enough to keep us informed of the tracks behaviour and if the track is safe to operate..
Better still, Move Solutions self configuration track tool on the Cloud Platform, allows you to build an accurate model of the length of rail being monitored which in turns drives the calculations and algorithms within the Platform.
The document available to download below, provides an overview as to how Move Solutions achieve this.
Earlier in 2021 Move Solutions founder and COO Ferdinando Frediani hosted a webinar discussing the importance of rail monitoring and how Move Solutions system can be adopted to deliver this.
One of the most exciting applications for Move Solutions patented Deck sensor is for monitoring the development of ballast voids below the sleepers. The Deck sensors measures the vibrational displacement of the structure the sensor is attached to and reports this in mm (accurate to 0.01mm). As detailed in the document downloadable above “The use of Deck allows to directly monitor the amplitude of oscillation of the sleeper as the train passes and its trend over time and to correlate its variation to the deterioration of the Ballast in which they are drowned.”
However the stated “Holy Grail“ of sensor based track monitoring is to be able to accurately measure the slew of the rail. As yet there is no sensor based solution to this and it continues to be the most challenging behaviour of the rail that is critical to the understanding of the lines safe operation.
As an alternative to using periodic total station measurements to targets placed on and around the track, we have witnessed laser distance meters being installed on to sleepers to measure their position in relation to a reference point on nearby structures. Often these reference points are on tunnel walls or adjacent embankments. As with data aquired by tiltmeters installed on to individual sleepers, the reliability of these laser distance meters for this application has to be questioned. As we cannot be sure that a lateral movement of a sleeper is directly related to a lateral movement of the rail, we equally cannot be sure exactly what the laser distance meter is measuring, as any rotation of the sleeper around the Z axis or roll around the X axis would change the point of reference the laser is aiming at and therefore would change distance measured.
With the enormous costs associated with rail infrastructure management, maintenance and monitoring, the reliability, accuracy and dependability of structural health monitoring systems adopted for this market is absolutely essential to the safe ongoing operation of the lines, the health and safety of the engineers and the ability to take well informed, early actions when lines become unsafe or present accelerated change towards being so.
For off-grid power systems, installation accessories and integrated sensors to support your adoption of Move Solotions structural health monitoring system please get in touch.
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