Statistical analysis on screening effects in urban areas against the electromagnetic induction from electrified railway lines

We have performed the field measurement to analyze the screening effects from the electricity feeder in electrified railway to telecommunication line in 30 urban areas and 30 rural areas for 3 years. After measurement we normalized the environmental parameters such as parallel distance, separation distance and soil resistivity in different areas to make a comparative study in same condition. Then we classified the data into 2 groups as an urban data group and a rural data group having 30 measurement places respectively. We analyzed each data group statistically and comparatively using the peak values at the time of passing through the measurement place to guarantee the objectivity and reliability of screening effects in these areas As a result of analysis by applying a statistical method, the comparative ratio of induced voltages between urban area and rural area appear from 0.275 to 0.847 as a probability density function in the 95% confidence interval.