Experimentally-Based Circuit Modeling Validation of a DC-Electrified Railway System for Rail Voltage and Stray-Current Evaluation

Despite advancements in mitigating stray current in railway systems, and their impact on nearby installations (i.e., pipelines), challenges remain, necessitating ongoing research and close collaboration between academia and the railway industry. This paper describes the relevant results of a joint industry–academia research project focused on the experimental validation of a reduced complexity circuit model to evaluate the rail potential and the associated stray current directly into the soil. It will be shown that the proposed circuit model is adaptable to various railway lines. Using a lumped parameter approach, the model simplifies spatial discretization without sacrificing accuracy; the relevant resistance and admittance parameters at the sub-stations and along the rail return path are identified, and their impact is studied for the subsequent experimental step. Two real scenarios involve two railway segments in southern and central Italy, which are also different in the geological profile of the terrain. The rail voltage along the two lines is measured and compared with the profile predicted by the lumped circuit model showing the latter’s accuracy. The circuit, validated by the experimental measurements, provides an indirect evaluation of the magnitude of the stray current flowing into the earth. Initially designed for uniform terrain, it can be expanded to include surrounding infrastructure and unintended stray current paths. This framework offers broad applicability and precision across diverse railway environments where nearby critical installations require the estimation of the stray current for the possible subsequent development of countermeasures for their reduction.