Due to the progress of digital transmission technology in recent years, the Digital Subscriber Line (xDSL) technology is attention as a high bit rate data transmission technology using existing metallic cables. In this paper, we report the performance and field test of xDSL transmission lines and introduce an estimation method summarized for the introduction of xDSL technology into railways. In this estimation method, after deciding the repeater spacing (distance between the stations), necessary transmission speed, required bit error rate, cable noise and the type and the number of existing systems in the same cable, we produce the type and the number of xDSL lines that can be introduced into existing metallic cables.

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