Field measurements

  • Train running past Fokstua on the Dovre railway line, Norway. Photograph by NTNU/Petter Nåvik.

     

     

  • Parts of the monitoring system mounted on a catenary system, master unit on supoport and one sensor by the steady arm. Photograph by NTNU/Petter Nåvik.

     

     

  • Some of the sensor mounted on the catenary at Hovin Station. Photograph by NTNU/Petter Nåvik.

     

     

Field measurements is an important tool for understanding and analysing the dynamic behaviour of a structure. In the case of railway catenary systems, it is important to assess the behaviour as train passes the investigated section. We have in collaboration with Elektromotus developed a monitoring system specifically for this application. The monitoring system is easy to mount and unmount, and has been successfully used to measure accelerations on existing, in use, railway catenary sections in Norway. The monitoring system consists of up to 10 sensors with a tri-axis accelerometer and a tri-axis gyroscope that can be arbitrarily mounted on the catenary wires, and a master unit that stores the data and controls that the measurements are sampled synchronously.

The monitoring system has been used to identify the amount of structural damping in existing railway catenary systems using Cov-SSI [1], see Figure 1. Study frequency content and possibilities with the monitoring system in [2], see Figure 2 and 3. Measurements sampled using the monitoring system has also been used for validation of the numerical model [3]. The monitoring system has been extensively used in conference papers [4–7] as well.

Figure 1 Damping parameter extraction from field measurements using Cov-SSI [1].

Figure 2 Frequency content of acceleration time series from 140 train passages [2].

Figure 3 Spectograms of the frequency response from hand excitation (a) S4 and train passages (b) S4, (c) S2 and (d) S8. [2]

In addition to the monitoring system we have worked with measuring displacements by close range photogrammetry. This have been used for the validation paper of the numerical model[3], and for a conference paper [8]. The comparison of the numerical and field displacements is presented in Figure 4.

Figure 4 Comparison between displacement time series obtained through numerical modelling with field measurement using close range photogrammetry. [3]

Measurements have been sampled on these locations:

  • Alna
  • Soknedal
  • Melhus
  • Hovin
  • Vålåsjø
  • Fokstua (old system)
  • Fokstua (new system)

References:

[1] Nåvik P, Rønnquist A, Stichel S. Identification of system damping in railway catenary wire systems from full-scale measurements. Eng. Struct. 113 (2016) 71–78. doi:10.1016/j.engstruct.2016.01.031.

[2] Nåvik P, Rønnquist A, Stichel S. A wireless railway catenary structural monitoringsystem: Full-scale case study. Case Stud Struct Eng 2016;6:22-30. doi:10.2016/j.csse.2016.05.003. 

[3] Nåvik P, Rønnquist A, Stichel S. Variation in predicting pantograph-catenary interaction contact forces, numerical simulations and field measurements. Veh Syst Dyn 2017;55:1265-82. doi:10.1080/00423114.2017.1308523.

[4] Nåvik P, Rønnquist A. Estimating the damping of existing railway catenary sections from full-scale measurements. Civil-Comp Proc 2016

[5] Rønnquist A, Nåvik P. Exploring dynamic behaviour of soft catenaries subject to regular loading using full scale measurements. Civil-Comp Proc., vol. 110, Civil-Comp Press; 2016

[6] Nåvik P, Rønnquist A. Uplift-monitoring for dynamic assessment of electrical railway contact lines. Conf. Proc. Soc. Exp. Mech. Ser., vol. 2, 2015, p. 237-44. doi:10.1007/978-3-319-15248-6_25.

[7] Rønnquist A, Nåvik P. Wireless Monitoring of the Dynamic Behavior of Railway Catenary Systems. In: Wicks A, Niezrecki C, editors. Struct. Heal. Monit. Damage Detect. Mechatronics, Vol. 7. 1st ed., Springer International Publishing; 2016.

[8] Frøseth GT, Nåvik P, Rønnquist A. Close range photogrammetry for measuring the response of a railway catenary system. Civil-Comp Proc 2016.