The measurement of the rail-to-earth resistance has important significance for the assessment of stray current.In an actual operating line

the measurement of the rail-to-earth resistance is interfered by the over-voltage protection device and so on.By establishing a two-layer model of the running rail-stray current collect mat

the distribution of the rail potential and current at the double-end grounding

ungrounded and single-ended grounding at the end of the line is solved

and the measurement error of the rail-to-earth resistance is analyzed.The average voltage measurement error of the running rail increases as the measurement interval increases.The measurement error of the leakage current decreases as the measurement interval increases.When the two ends of the running rail are grounded

the measurement error of the rail-to-earth resistance can reach 1.20■·km.It is recommended that the length of the rail-to-earth resistance measurement interval should be controlled within the range of 1～4 km.When the average potential calculation of the rail considers its approximate linear distribution

the average rail potential error is less than the arithmetic mean value

and the measurement error of the rail-to-earth resistance can be reduced.