The structure of this chapter is as follows: first, we explain non- transmission-based signaling (TBS) systems, that is, distance to go and some other signaling systems that do not rely on radio communications to work. Then we go into the core of the chapter: European Rail Traffic Management System (ERTMS) and communications-based train control (CBTC), which are best two examples of TBS and the dominant ones in the market for both high-speed line (HSL) and main line (for ERTMS) and subways (CBTC). Then we explain the different grades of automation of a railway line which are enabled by TBS. Finally, we provide an insight of operational control centers (OCC) to explain how those lines equipped with TBS on its tracks and trains are operated. As usual, there are two more sections at the end of the book: Exercises and Further Reading.