In recent years, Digital Subscriber Line (xDSL) technology is attracting attention as a high bit rate data transmission technology using existing metallic cables. In this paper, we discuss the introduction of xDSL technology into railways as a data transmission method by metallic cables. First, we describe an outline of the metallic cable transmission systems in railway operation. Second, we list the subjects to be discussed for introducing the xDSL technology into railways, and report performance and field tests of xDSL transceivers. In these tests, we were able to prospect the xDSL technology and obtain part of basic data for introduction into railways.