The national transporter has recently installed 4,920 such devices in the most fog-affected railway zones -- northern, north-central, north-eastern and north-western. Plans are afoot to install an additional 1,175 such devices in two more zones by this Friday -- east-central and northeast-frontier -- to take the total to 6,095, covering the most-affected zones.



"In the absence of this device, (the) crew has to reduce speed, often to walking speed in search for signals. With the deployment of FSDs, train pilots are able to know precisely and, in advance, about the location of signals, level-crossing gates and other such approaching markers," an official said on Tuesday.

Any approaching landmark will be announced by a recorded voice before 500 metres and three pre-fed marks are shown at a time on the display unit in bold letters, along with the distance to reach the first landmark. Speed and time are also displayed on the right-bottom corner. There is also a provision to cross-check history, the official added.