New Measurement Methods for Transition Resistance of Rail Tracks in Urban Rail Transit

[Objective] To analyze the impact of stray currents on buried pipelines and electrical equipment during metro operation, it is necessary to study new measurement methods for the transition resistance of rail tracks in urban rail transit. [Method] The principle of measuring rail track transition resistance is introduced. To address the challenges in measuring rail track transition resistance, a novel measurement method utilizing an impulse current source is proposed. Based on the characteristics of metro tunnel construction and the propagation behavior of impulse current in rail track structures, a simulation model for rail track transition resistance is developed. The transition resistance values are calculated using the simulation model, and on-site measurement tests are conducted as a case study on a Shanghai urban rail transit line. The measurement results by the traditional DC method and the impulse current method are analyzed and compared. [Result & Conclusion] As the rail track transition resistance increases, the measurement error of the impulse current method gradually decreases and remains within 5%. The impulse current method features lower requirements for on-site conditions and measurement objects, simpler external wiring, higher operability, and stronger anti-interfe-rence capabilities. Through multiple on-site measurements, the error of the rail track transition resistance measured by the impulse current method is approximately 1.3%.