There are certain engineering works such as track renewal work, bridge rehabilitation work, etc., that stretch over a few days and thus the track is required to be protected to ensure the safe journey of trains.
348 Railway Engineering
When a track is under repair, trains are required to proceed with caution at restricted speeds and may even be required to stop. Temporary engineering indicators (Fig. 18.4) are set up at the affected portion of the track to alert the drivers to reduce the speed of (or even stop) the train and also to resume the normal speed once the affected portion has been treated. The following indicators are used.
Fig. 18.4 Protection of track for works of long duration
Caution indicator This indicator cautions the driver to get ready to reduce the speed of the train (Fig. 18.5). It is placed at a distance from the stop indicator- 1200 m away on BG tracks and 800 m away on MG and NG tracks.
Termination indicator This signal indicates that the driver can resume normal speed and that the speed restriction zone has ended (Fig. 18.6).
Speed indicator The driver has to reduce the speed of the train at location bearing this indicator (Fig. 18.7).
Stop indicator The driver is required to stop at locations bearing this indicator (Fig. 18.8). It is normally placed 30 m away from the obstruction.
These indicators are also called temporary fixed engineering signals and are provided in the direction of the approaching train in the case of double-line tracks and in both directions in the case of single-line tracks. These signs or indicators should be luminous as per the latest policy of the Railway Board.
Fig. 18.6 Termination indicator
Fig. 18.8 Stop indicator