Signals, which ensure safety on railways, play a different role from road signals. While the driver of an automobile determines the appropriate distance from the preceding car, the railway signaling system is responsible for this. Railways have also introduced and evolved train control systems to prevent accidents that could occur due to driver error and other factors. In addition, an operation control center system has been introduced. The train's location is an essential piece of information for these signaling and traffic control systems. The track circuit has consistently been used as the device for this train location detection in Japan. Still, recently, a radio-based method has also been used in some lines. Maintenance of railcars, tracks, and other equipment is also essential to safety. Digital technologies such as artificial intelligence (AI), big data, and robotics are rapidly being introduced in signaling, train control, location detection, and maintenance. For the English edition of the book, we have added earthquake countermeasures for railways, unique to Japan, a country that frequently experiences earthquakes, including several significant earthquakes.