Page 178 - IRSEM_Main Book

7.5.4 Interlocking of Catch/Slip Siding points with Block Instruments
The interlocking shall be such that the key required to set the siding points is
released from the instruments in the "Train Going to" / "Train Coming from"
position and once the key is removed from the block instruments, the
instrument gets locked in the relevant position. The instrument can be
normalised only after the points are set for the Slip Siding/Catch siding and
the "Train Going To" / "Train Coming from" key is released from the Points
and brought back to release the instrument.
Where a Slip Siding is located at the departure end of a Double Line Station,
the interlocking shall be such that the Points can be set towards the Block
section only when the block instrument is set to “Line Clear".
Note: Please refer to SEM Chapter 18 for Block working.

7.5.5 Audible Indication: An audible indication shall be provided at the place of
operation of Points as an aid to the Operating staff, indicating that the train
has been received or despatched and that the points shall now be normalised
for the Catch Siding/Slip Siding. This indication would continue till the points
are normalised for the Catch Siding/Slip Siding.

7.5.6 Safeguards in working: In all cases where interlocking arrangements
stipulated in Para 7.5.4 are provided between the Slip/Catch Siding and the
block instrument, the following safeguards shall also, inter alia be provided in
the Station working Rules:
(a) Shunting on non-isolated lines shall cease once Line Clear has been
granted.

(b) Points shall remain set and locked for the Catch Siding until Home
Signal has been taken 'OFF'.

(c) Before normalising the block instrument the Station Master/Assistant
Station Master, shall verify the complete arrival or despatch of the train,
even though he is getting an audible warning, which may be due to
reception or despatch of a complete train or part thereof.

7.5.7 An Emergency Key of the Catch/Slip Siding shall be kept in a sealed box
under the custody of the Station Master. This is used for operating the Slip
Siding/Catch Siding points when either the block instruments have failed, or
when the train is still in the Block section and another train is required to be
despatched into the Block section.

Chapter 7: Essentials of Signalling Page 147 of 535