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International Journal of Railway Technology
IJRT, Volume 6, Issue 3, 2017
Operational Displacement Estimations of Railway Catenary Systems by Photogrammetry and the Integration of Acceleration Time Series
G.T. Frøseth, P. Nåvik and A. Rønnquist
Department of Structural Engineering Norwegian University of Science and Technology, Trondheim, Norway
G.T. Frøseth, P. Nåvik, A. Rønnquist, "Operational Displacement Estimations of Railway Catenary Systems by Photogrammetry and the Integration of Acceleration Time Series", International Journal of Railway Technology, 6(3), 71-92, 2017. doi:10.4203/ijrt.6.3.4
Keywords: displacement estimations, contact wire uplift, railway catenary system, close-range photogrammetry, wireless monitoring, field measurements, pantograph catenary interaction, structural dynamics.
The dynamic behaviour of railway catenary systems is critical for the quality of the power supply as well as for the amount of wear on both the wires and pantograph. To date, the assessment of the dynamic behaviour of railway catenary systems has focused mainly on the contact force measured from the pantograph. Some examples of using displacement and acceleration measurements sampled at specific locations on the catenary can be found in the literature. Recent work has used wireless accelerometers, which are able to sample accelerations at any location of interest on the catenary system to assess the dynamic behaviour with success. Although accelerations give valuable information about the dynamic behaviour of the systems, it is also desirable to know the displacements. Accelerations have proven easy to sample, so it is natural to integrate these into displacements to obtain the desired displacements. A more direct method to measure the displacement is photogrammetry. This paper describes and uses photogrammetry for operational estimations of the displacement and uses it to successfully validate a procedure for integrating the accelerations into displacements for railway catenary systems. Finally, one week of train passages is recorded, integrated, and statistically evaluated to analyse the validated integration procedure used in daily operation monitoring. The evaluation shows single-passage and extreme value distributions with up-crossing frequencies of up to 1/10,000. The 95-percentile threshold value for the yearly probability of exceedance is also included and compared to the maximum allowed uplift at the cantilever. Finally, the yearly probability of failure is estimated at Fokstua.
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