Stray currents for instance caused by DC traction systems can have a harmful effect on the Cathodic Protection system of, for example, a gas pipeline. These stray currents are formed whenever the traction current in a railway system does not flow back to the substation through the track but via the soil. If this is the case, currents use the gas pipe as a conductor. After all, electrical current always seeks the path of least resistance. The stray currents may then disrupt the pipeline potential to such a degree that the CP-system is no longer able to prevent corrosion.

Also, stray currents may influence the soil at railroad crossings. It is remarkable that in winter when the roads are salted, all of a sudden the electrical connection between the track and the soil is very good. When this happens, the soil is affected by the tensions of the track. If there is a pipeline with a Cathodic Protection (CP) system in the vicinity of the railroad crossing, the pipeline potential relative to the soil becomes so small that in specific spots the pipeline is no longer sufficiently protected. As a result, the possibility of corrosion increases. That is why it is very important to conduct influence measurements during different seasons of the year.