COGI: Optical Control of Insulating Joints

COGI app adds to NeuRAIL, the ability to constantly monitor in real time the longitudinal movement of the two joined rail section with the primary scope to identify in time, an incipient or total failure of the glued insulating joint.
It allows to measure remotely, with continuity and in real-time, with micrometric resolution scales, the deformations that occur overtime to the Glued Insulating Joints - in particular the ovalization of the holes of the jaws produced by the cyclical action of dynamic loads and thermal excursions and consequent detachment of the joints – thus allowing to identify and promptly intervene on anomalous deformations and misalignments that often cause railway accidents.

The constant high-frequency measurement allows performing predictive analyses based on:

• The count of the number of axles in transit during the life cycle of the joint
• Data inferred from constant environmental monitoring
• The statistic parameters required to implement the available models

Insights: COGI, how it works

COGI is a passive optical device featuring magnetic anchoring systems that allow to quickly apply it to any type of track. Through two plug-and-play connectors, it is connected to a troubleshooting framework developed specifically that, from remote server or in cloud, allows to constantly monitor the opening of the joint, at a kHz frequency and with micron resolution, thus it is able to identify not only the typical detachment but all movements and micro-movements of the insulating joints.

COGI’s core, its sensitive part, consists of an optical fibre filament featuring a Bragg mesh specifically prepared – upon GCF’s design and patent – by Diamond SA, which transforms the fibre filament into a precision opto-mechanical transducer. The same company manufactures, in addition to the sensor, the fitting cables using low-loss connectors designed to withstand hostile environments and maintain a high protection level. The traction/ compression longitudinal mechanical deformation that undergoes the optical fibre induces a geometric variation of the mesh that, in turn, causes a variation in the wave length of reflexed light. This way, the troubleshooting software can obtain the fibre’s deformation in an accurate and repeatable manner, compare it with the variations generally induced by temperature changes and verify when a normal standard level is exceeded.

the validation steps in the field

The innovative system, unique in its kind, designed according to RFI’s technical and functional specifications, tested and certified in the Laboratory, has ben verified and validated on-site for many months by accredited certification bodies.

In recent months, Ferrovie Emilia Romagna has promoted COGI installation and the execution of validation tests on-site at the railway complexes of Crespellano station, along Casalecchio-Vignola (km 12+579) line where seven Glued Insulating Joints were found, monitored with Cogi. For three months a software specifically developed has collected the data transmitted by Cogi while, at the same time, the regular visual inspection activities conducted by FER’s staff continued. For testing, a tool was chosen with sampling frequency of 1 kHz and wave length resolution of 8 pm, corresponding to a spatial minimal resolution of about 10 micron.

Two particular stress-tests were carried out at the same time, to test the reaction modes, hence COGI’s “discernment” modes were tested, at the transit of trains and also of railway means that carry out the maintenance of tracks and screed: also in this case COGI’s sensor continued to read the deformation of the joint during and after the tamping operations without any damages, interruptions or movements such to exceed the alarm thresholds.