Rail Signaling System is the most important part of the Train Control System. The adopting technology has been developed from relay system interlocking, computer based interlocking, to CTCS-2, CTCS-3. The communication has been developed from traditional hard wire, serial communication to present industrial Ethernet. For the purpose to establish a safe, reliable, standard uni!ed new generation of security data network, China Rail Corporation has released the Standards of High Speed Rail Signaling System Security Data Network, Version 3.0. It defines all the functional requirements, networking requirements, the selection of equipment, network structure, network management and etc. for the Security Data Network.

Mass Transit system is one of the most important infrastructures in the modern cities, while its Signaling system is the core of an efficient and effective train operation. Over the past decade, CBTC (Communication-based Train Control) technology is widely implemented throughout the world for urban transportation, which requires a highly reliable DTS (Data Transmission System).

TCMS (Train Control and Management System) is the core of train operation, which carries several critical services, such as traction power, auxiliary power, speed, location, braking, door control, HVAC, train status monitoring and diagnosis. With the popularity and maturity of Ethernet technologies, an IP based TCMS and related specifications such as ETB (Ethernet Train Backbone) and ECN (Ethernet Consist Network) are de!ned in IEC61375.

Accurate & reliable operation of Passenger Information and Public Address Systems are the primary factors for passenger satisfaction. PIS/PA are generally composed of display board, broadcasting audio system, and a reliable communications network, not only the onboard network but also the ground network towards the operation control center.

In order to retain smooth and effective ticketing operation for railways, automated fare collection (AFC) system is introduced to modern transportation. It generally consists of ticket vending machine, fare gate and backend accouting system. Though it's less critical for train operation, it's most critical for the operator working capital.

Integrated Supervisory and Control System, ISCS plays a crucial role to make a centralized and comprehensive operation for city metro. All the major systems, from vital to non-vital, from the field to center, such as AFC, PIS/PA, Clock, CCTV, BAS, FAS, PSCADA, ATS, TMS... etc. can be integrated into one single supervision and control room.

Traction power supply systems are the basic infrastructure for train operation. Transformers, switch-gears, low-voltage power distribution and control/protection devices are installed along the tracks, while the Power SCADA system ensures the service availability through its real time control and supervision.