Page 410 - IRSEM_Main Book

(h) Token instruments shall be so installed that a token of one block section
can not be placed in the instrument of an adjacent section and preferably
such that if the token is over carried, it can not be placed in an instrument at
the next station.

(i) The Tokens of each section shall be engraved with the code name of the
stations at both ends of the block section and with a serial number.

18.1.3 Special Requirements of Single Line Tokenless Block Instruments

(a) Fixed Indications: In addition to the fixed indications specified in para
18.1.2(a) the instrument shall be provided with means to indicate "Train On
Line" at both the sending and receiving stations when a train has entered
the block section.

(b) Immunity from Extraneous Currents: Single Line Token less block
instruments shall work on coded impulse/frequency modulated current
system so as to be immune from the effects of extraneous currents.

(c) "Train Going To" and "Train Coming From": The instrument shall be
such that even with the co-operation of the Station Master at the other end
of the section, the Station Master has to go through one or more definite
moving operations on the instrument in addition to the working of bell
plunger.

(i) Before he sets his instrument to "Train Coming From".

(ii) Before he sets his instrument to "Train Going To".

(d) "Train On Line": Means shall be provided to ensure that the instruments
are set to "Train On Line" automatically by the entry of the train into the
block section and maintained in that position until the train has cleared the
block section. This indication shall be in addition to the "Train Going To" or
"Train Coming From" indications of the handle.

(e) "Line Closed": Both the instruments shall be restored to normal before a
further operation of setting the instrument to "Train Going To"/"Train Coming
From" can be carried out. It shall not be possible for the instruments at
either end of the section to be restored to normal without the co-operative
features enumerated in para 18.1.3(c).

18.1.4 Operations: Push Button Tokenless Block Instruments

(a) "Train Going To" and "Train Coming From": The co-operation of the
Station Master at the other end of the section may be dispensed with. The
instrument shall be such that a button in addition to the bell button shall be
operated for "Train Going To" position.

(b) "Train On Line": Means shall be provided to ensure that the instruments
are set to "Train On Line" automatically by the entry of the train into the
block section and maintained in that position until the train has cleared the
block section. This indication shall be in addition to the "Train Going To" or
"Train Coming From" indications.

Chapter 18: Block Instruments, BPAC & IBS Working Page 358 of 535