The rapid progress of power line communications (PLC) for data transmission over electric power supply systems is now opening ways for special applications such as train automation in local transportation and mass transit (MT) systems. These DC-powered traction networks can be used as communication links between wayside equipment and the moving trains. As MT networks significantly differ from usual electricity supply systems, the usage of existing models and communication equipment for conventional PLC channels turns out infeasible. Therefore, the work reported in this paper focuses on MT channel investigation and modeling, in order to develop novel adapted solutions. The outcome is a stochastic MT channel model, which-besides multipath and time-variance-also includes peculiar properties such as the behavior of ring structures and the impact of the Doppler effect invoked by moving trains. In addition, a very special interference scenario is treated, caused by the rectifiers in these DC-powered environments. Besides a complete simulation model, this paper presents detailed guidelines for building emulation hardware, so that channel adapted PLC system design for MT networks can now be successfully started without further expensive field trials.