Signal Analysis for Railway Systems

Temperature monitoring of axle bearings and brakes on passenger and freight trains is an important factor for the reduction of downtimes or maintenance expenses. Measurement requires contactless methods. This is typically done by sensors which are mounted in the track to measure thermal radiation of the passing chassis. The data is subsequently analysed by mathematical methods. In a long-standing and successful cooperation with the company Progress Rail Inspection and Information Systems (PRIIS), we are developing the software for the chassis monitoring sleeper (FUES). The software analyses radiation profiles, detects overheating components, and transmits results to registration centers.

Problems and Solutions

Large amounts of sensor data must be processed during normal operation. Changing ambient temperatures influence the sensor properties, which makes permanent (post-)calibration of the devices necessary. Our system software does this automatically. If the measured values deviate strongly during the calibration process, for example because of temporary contamination of the optics (f.ex. by condensation), this is detected and algorithmically corrected. The measured temperatures thus remain stable over long periods. Even unwanted interference radiation caused by to sun reflections or hot brake pads is detected and filtered out by intelligent classifiers.

In addition, the recognition of individual vehicles on the basis of their axle spacings allows an adaptation of the evaluation parameters to the design-related differences of individual wagons.


During the development and implementation of the algorithms, emphasis was placed on the high availability and reliability of the system. The algorithms are constantly improved in our laboratories and supplemented with additional functions. The entire system is modular and flexible and can be easily adapted to individual requirements.

Signalanalyse im Eisenbahnbereich
© Fraunhofer ITWM
Signal Analysis

System environment

The evaluation computer consists of an industrial PC running under the Linux Operating System. In addition to the evaluation software, further software packages such as system diagnostics programs and a web-based user interface have been developed.


The software is used worldwide. More than 1000 measuring systems have already been installed in Europe alone.



  • Progress Rail Inspection & Information Systems GmbH


Further Information

An article concerning this subject can be found in our Annual Report 2021/22

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