A detailed investigation of uplift and damping of a railway catenary span in traffic using a vision-based line-tracking system

For electrified railways, the catenary dynamic behavior is critical to ensure a robust and steady current collection quality for electric trains. The current collection is achieved as the catenary directly interacts with the pantograph, installed on the car-body roof to provide an electrical current to the engine. Damping plays an essential role in numerical simulations of pantograph catenary interaction, especially for multiple pantographs. However, damping estimation of existing catenary sections is recognised as a challenge, and only a few studies have been published with single values of damping estimations. This study aimed to estimate the spatially distributed damping of an existing catenary span through full-span uplift measurements using a vision-based line-tracking system (VIBLITE). A detailed study was performed at critical locations along the catenary span. Sixty-nine single/double-pantograph train passages were acquired during scheduled train operation. Time series of uplift and acceleration were obtained through a line-tracking image-processing technique. The uplift amplitude was statistically analysed, where the damping ratios were identified using the covariance-driven stochastic subspace identification (Cov-SSI) method. Finally, the spatially distributed Rayleigh damping coefficients were successfully identified to quantify the important spatial variation in energy dissipation within a span. Arithmetic averages of damping coefficients over all measuring locations were obtained and recommended for future numerical simulations.