200202 – Abbott – Safety in the Middle – Engineering SCADA Systems for Safety-related Railway Applications

Today’s railway control systems provide a spectrum of functionality and are essential for railway operators to meet their key business and performance objectives. Supervisory Control and Data Acquisition (SCADA) systems are an ever increasing class of control system used in the railway environment, not only for the traditional traction power control function, but also as the platform for integration of modem railway control and communications system applications.

Rail SCADA customers demand that these systems not only provide the desired functionality but also achieve desired safety integrity levels. Although SCADA systems are rarely relied on to provide the sole mitigation against high risk hazards, they are frequently used to contribute to the management of hazardous situations, or to implement partial defences. As such, in some applications, SCADA systems are safety-related systems (as opposed to safety-critical systems) and are nominally considered as SE 1 or 2 systems.