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Inspection and condition monitoring of rails

MonitoRail - Long-range inspection and condition monitoring of rails

Throughout Europe more than 2,600 broken rails are found every year leading to reduced reliability of the rail network and resulting in severe delays and potential derailments. Rail maintenance costs associated with the occurrence of broken rails is estimated to cost European member states more than €2bn per annum. With the rapid and continuous increases in train traffic, speed and tonnage carried on rail networks, there is an urgent need to increase the reliability of rail infrastructure and optimise maintenance. It is therefore necessary to use efficient and cost-effective inspection and monitoring methods which will enable the accurate evaluation of the structural condition of rails. Guided wave ultrasonic inspection is different from conventional ultrasonic inspection, since an array of transducers fitted around the outside of the part being inspected sends a sound wave along the length of the component, rather than through it. The component itself constrains the waves along its length. The received signal depends on the nature of the reflecting surface. Therefore, discontinuities such as fractures, inclusions, corrosion or metal loss can be detected by analysing the reflected wave.


The project aimed to reduce the substantial costs related to rail inspection and monitoring and aimed to contribute to achieving the target set by the European rail industry to reduce the overall maintenance expenditure by 30%, by 2020.

The objective of MONITORAIL was to develop a cost effective guided wave ultrasonic condition monitoring system, along with a long range, low power, wireless communications system, in order to improve and better maintain the European railway system for improved efficiency and safety.

Using guided waves, long lengths of rail track can be monitored from a single point, making this a cost-efficient technique for continuous monitoring. The condition monitoring of rail will extend the life of the materials by more accurately identifying the point at which maintenance or replacement is necessary.

The project developed:

  • novel sensor arrays that will be embedded in the railway
  • a low power, data collection system
  • a software programme to process signals, analyse the data and present the resulting anomaly identification and its position
  • a wireless method and equipment for transmission of data from trackside to a central base station


The rail is a natural wave guide where waves can easily propagate for long distances and detect defects in different areas such as the head, the web and the foot. Using guided waves, the track can be monitored without affecting track availability.

Project Partners

  • TWI Ltd
  • Brunel University London

For more information, please visit the MonitoRail website.

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Project last modified 18/05/2021