Evaluation of relative merits/demerits of different signalling schemes used on Indian Railways

Presence of Railway stations are essential for train traffic control (to enable crossings and precedence). Movement of trains at stations are controlled by Signals. In busy trunk routes, the running time of trains in station area is comparable to that between stations. Indian Railways use different signalling schemes to enable movement of trains in a safe manner. The signalling schemes play an important role in determining the action of the driver in terms of slowing down of trains and consequently on the throughput of the railway system. This paper examines the different schemes of signalling used currently and in recent past by Indian Railways from the point of view of information that they present to the train driver and the impact that it has on total throughput. The signalling schemes are compared using total signal entropy presented to the driver at each stage. Apart from theoretical computation of signal entropy, results of some experiments conducted on impact of signalling schemes on run time of trains are also presented.