The first trial section of track examined with the rail
inspection train (Fig. 12) had the aim of comparing the
results received with different scanning speeds to
the results from manual inspection in order to estimate
the accuracy of the inspection system. In Fig. 12 results
are presented which were recorded at different scanning
speeds. By this original data are the vertical axis the
amplitude of the received eddy current signal. It is
apparent that there is an extraordinarily high-degree of
reproducibility, which demonstrates the reliability and
accuracy of the eddy-current measuring system used. It is
also noticeable that head checks are still present in the
reground section of rail. This indicates an important area
of application for eddy-current testing: assessing the
quality of regrinding work by checking whether the re-
profiling operations have indeed been successful in
removing all the head checks. A further example is
shown in Fig. 13 in which the results of the manual
Fig. 13. Measured data different scanning speeds.
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R. Pohl et al. / NDT&E International 37 (2004) 89–94
inspection are compared with those of the inspection
train. For this particular case the train speed was 76 km/
h. The results compare well.