Detrimental effect of stray current on rails and fastening systems in urban railway tracks

Abstract

In urban railway tracks, the rails serve not only to guide the vehicle, but also as a return conductor for the current the vehicle needs to run. If the rails are not properly insulated, stray current will flow from the rail to the lower part of the track and cause corrosion damage to metal structures near the track. In this study, the damaging effect of stray current on track components (rail and fastening system) was analyzed. The experiment was performed on two identical samples of a rail fastened to the concrete base with a direct fastening system. Both samples were immersed in water, and one of the samples was also treated with a constant direct current from the laboratory power supply via a stainless steel electrode. After 168 days of testing, 3D scans of the rails and clips were made using the ATOS measuring system, comparing the corroded with the reference samples. Applied current caused severe localized corrosion on the rail and rail clips, creating sharp edges that can lead to significant stress concentration under load, accelerate cracking, and contribute to fatigue failure.