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Details of Grant 

EPSRC Reference: EP/C534808/1
Title: New Instrumentation for the Scientific Study of Rail Defects
Principal Investigator: Dixon, Professor SM
Other Investigators:
Researcher Co-Investigators:
Dr RS Edwards
Project Partners:
London Underground Ltd N D T Solutions Ltd Network Rail
RWL (Roger West Laboratories Ltd) Serco Tata Steel Limited
Department: Physics
Organisation: University of Warwick
Scheme: Standard Research (Pre-FEC)
Starts: 01 September 2005 Ends: 28 February 2009 Value (£): 269,827
EPSRC Research Topic Classifications:
Civil Engineering Materials Transport Ops & Management
EPSRC Industrial Sector Classifications:
Transport Systems and Vehicles
Related Grants:
EP/C534824/1 EP/C534816/1
Panel History:  
Summary on Grant Application Form
Rail transport will play a more important future role in the UK and worldwide than is currently the case. In order to have a viable rail network we will need reliable infrastructure that is safer to travel on and is also optimally managed for maintenance. There are probably improvements and developments that will be made in signalling and in the civil engineering of the track and track bed that will be of great benefit. We do however need to recognise that the rail itself will always be subject to 'wear and tear and that under certain demanding conditions, that this rail will at some point develop defects. There are clearly steps that can be taken to extend the useful life of track, but we ultimately need to acknowledge the fact that as we demand more performance from tracks through increased traffic and loads and higher speeds we will need to optimise track maintenance. If we do not improve track inspection then we run the risk of having a costly and inefficient system or one in which safety could possibly be compromised. Currently inspection systems typically use several send-receive ultrasonic transducers mounted in a wheel probe rolled along the surface of the track, sending ultrasonic compression and shear waves down into the rail. This transducer must move no more than 1 mm or so along the rail in the time it takes for ultrasound to propagate from the transducer to the deepest defect and back again. If the wheel moves too quickly along the track it will be in the wrong position to detect ultrasound reflected from a defect in the rail, which in practice this limits inspection speeds to around 20-30mph. Another major limitation with the current bulk wave inspection techniques is that they can be blind to surface defects such as gauge corner cracking where a shallow, tolerable crack can block the ultrasound from penetrating down to a much deeper crack behind it. Current systems can potentially miss serious defects and cannot be used with high regularity due to their speed limitations.We will develop an instrument for high speed inspection that could be deployed on passenger trains in service. This will improve safety and allow the track to be efficiently monitored and managed leading to significant cost savings in terms of track management and a more efficient rail network. We will build on our recent scientific developments in transducer design and signal processing, combining state of the art ultrasonic expertise with rail engineering technology and material science expertise. We have recently published work that shows by using wideband ultrasonic surface waves that have a range of different frequencies present in one ultrasonic pulse that we can detect and determine the depth to which cracks penetrate. Lower frequency components penetrate deeper into the surface of the rail and thus by looking at the extent to which different frequencies are blocked or are able to propagate underneath the crack we are able to gauge the depth of the crack down to beyond depths (-15mm) where they become safety critical. By using transducers separated by a fixed distance to generate and detect the surface wave we overcome the inspection speed limitations experienced with the conventional system. We also propose new techniques suitable for high speed bulk wave inspection that overcome the speed limitation problem by using a 'through transmission' approach where a broad beam of ultrasonic bulk waves are propagated from one side of the rail head to the other. A defect within the bulk of the rail head will block some of the ultrasound propagating through the rail and create a 'shadow' region in the ultrasonic wavefront detected on the other side of the rail. Several approaches using different combinations of contact and non-contact ultrasonic transducers will be evaluated. Engineering this technology onto a rail inspection device will be a major undertaking and the involvement of rail technology experts from the EPSRC funded RRUK is vital.
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Organisation Website: http://www.warwick.ac.uk