16-01-2017, 01:23 PM
I was not sure what a POP group was.
POP group - Predetermined Overrun Protection group
"A group of signals replaced to danger by the signalling system after a SPAD: the grouping is agreed in advance in consultation with operational specialists."
"NR/L2/SIG/30009/E421 describes the extent of the required predetermined protection for each signal"
Ref: NR/L2/SIG/30009/E420 Issue 2, March 2015
I understand it is an automatic reaction to a SPAD as part of overrun management implemented in the control system (i.e. IECC) rather than the interlocking to reduce complexity in the interlocking ('simpler is safer') and to reduce cost (~SIL 2 cheaper than ~SIL 4).
POP group - Predetermined Overrun Protection group
"A group of signals replaced to danger by the signalling system after a SPAD: the grouping is agreed in advance in consultation with operational specialists."
"NR/L2/SIG/30009/E421 describes the extent of the required predetermined protection for each signal"
Ref: NR/L2/SIG/30009/E420 Issue 2, March 2015
I understand it is an automatic reaction to a SPAD as part of overrun management implemented in the control system (i.e. IECC) rather than the interlocking to reduce complexity in the interlocking ('simpler is safer') and to reduce cost (~SIL 2 cheaper than ~SIL 4).