Evaluation of relative merits/demerits of different signaling schemes used at a railway station for an approaching train in Indian Railways today

Indian Railways, one of the largest railway networks in the world today, has a peculiarity that a station exists almost every 5-7 km. Most trains do not stop at all stations and run through more stations than they stop at. The speed at which the trains run through the stations, therefore, is a crucial parameter that determines the run time of a train through a section and, hence, the total throughput (or carrying capacity of the railways). Indian Railways uses several signaling schemes to enable movement of trains in a safe manner. The signaling 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 signaling schemes used currently and in the 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 signaling 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 to obtain the impact of signaling schemes on run time of trains are also presented