This textbook provides a comprehensive treatment of railway communications systems and their ever-evolving interconnectivity, smart systems, and complex grids. The author first provides an introduction to railways and goes on to detail wayside networks, onboard networks, safety systems, and services that rely on these networks. In particular, the book covers application aspects, including network and physical layer, maintenance, and technologies that will shape the railway of the future. The book also covers rolling stock networks and systems and details the railway ecosystem that will help people new to the topic understand the core material. The book is oriented to educational purposes in classes such as Intelligent Transportation Systems or Communication Systems Architectures and also for practicing railway engineers. The textbook features supplementary material including homework problems, exercises and more. Provides a comprehensive treatment of railway communications systems for classroom use; Covers topics such as safety, networks, train-to-ground systems, the physical layer, maintenance, and more; Includes a full suite of classroom materials including homework problems, exercises, and more.