National Physical Laboratory

Thermography at the wheel-rail interface

In the extreme environment at the wheel-rail interface, where railway train wheels contact the rails, mechanical work done by the wheel on the rail rapidly ends up as heat. So thermal imaging of the wheel-rail interface can potentially reveal energetic wheel-rail events in real time (e.g. slippage). Following on from in-house experiments NPL has undertaken two field tests to investigate the practicality of the technique.

Download the case study here Adobe Acrobat PDF file


Rail-yard tests

Tests in the Serco Railtest yard showed that thermal cameras could indeed detect transient events at the wheel rail interface.

Fig 1: A thermal camera attached to the a carriage in a yard   Fig 2: Thermal image of the wheels undergoing sideways slip as it approaches points

Fig 1: A thermal camera attached
to the a carriage in a yard

 

Fig 2: Thermal image of the wheels undergoing
sideways slip as it approaches points


High-speed tests

A commercial-grade (60 frames per second) thermal imager was fitted into the existing housing on the Network Rail Measurement train and data was acquired at speeds up to 108 mph. The relatively low speed of the camera 'blurred' the contact-point images but it was possible to determine the position of wheel-rail contact and interesting dynamics were found near points. In particular, otherwise undetectable double-contacts and flange-rail events were easily observed. The information collected has been used to develop a thermal model of wheel-rail events.

Fig 3: A 60 frames per second thermal camera fitted inside the existing camera housing   Fig 4: Attaching the camera to the Network Rail Measurement Train

Fig 3: A 60 frames per second
thermal camera fitted inside the
existing camera housing

 

Fig 4: Attaching the camera to the
Network Rail Measurement Train

 

Fig 5: A thermal image acquired at 108 mph showing double-contact at the wheel rail interface   Fig 6: A thermal model of the rail head was able to deduce the thermal signature of characteristic wheel-rail events

Fig 6: A thermal model of the rail head was able to deduce the thermal signature of characteristic wheel-rail events

Fig 5: A thermal image acquired at 108 mph showing double-contact at the wheel rail interface

   


We are now seeking potential partners to take this activity forward.

Contact

For further information, please contact Michael de Podesta

Last Updated: 1 Feb 2017
Created: 27 Jan 2016

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