The paper will, therefore, attempt to put signal and control systems into a wider context, describe the potential benefits that can be achieved, and touch on some of the techniques that are available. It will concentrate on the railway itself and not on the railway as part of the national or city infrastructure as this is dealt with in the later paper by Phil McKenna. Inevitably, because of the author's background, the examples will tend to be drawn from Metro Railway Operations but they are applicable to all railways, albeit that they have the advantage of a simpler political, contractual and geographical framework within which to work.