10-01-2010, 12:14 PM
I have now commenced to look at the Indian style Control Tables for HEBSUR on South Western Railway- obviously have no means of knowing whether there are a range of practices across the areas of the country or evolving over time as echnology advances (as per the UK situation) so my comments are purely based on what I have seen.
I deduce that the yellow aspect in India is primarily part of "speed signalling" for going into and out of loops or other turnouts etc rather than relevant to braking distance between signal posts in the "route signalling" that the UK uses. Hence it appears that my basic assumption that India would, because of its historic ties, have followed the UK rather than the European precedent is incorrect; I now guess that it may have been more based on USA or perhaps Australian practice.
The other thing that is very clear is that the locking, although with colour light signals, is actually very much that which I'd associate with "mechanical signalling" and the aspect controls seem to extend for two signal sections (i.e. in UK terminology the overlap of the signal section is in fact the entire route of the next signal section rather than to a specific defined track joint along that route). This has implications as the "exit" of the first route seems to be defined to be the line on which the 2nd signal in advance is depicted, rather than that of the exit of the route as I'd see it. I suppose the approximate equivalent in some ways of the UK Warner route is the ability at some loop signals to set a route to an exit signal with the points are set to divert any SPAD to a specifically provided overrun line and hence give the running line trapping protection.
The backlock tracks seem to be what the UK would have as sectional route locking release track circuits from the protecting signal to the last set of points in the route. This is just like mechanical practice whereby the only locking on the points is from the signal and therefore the signaller must not restore the signal lever until the last set of points have been traversed. Indeed this I believe is similar to London Underground, except that they require additional proof that the (fixed length formation but lightweigh train) has indeed cleared the area by using someother device (such as a Delta track) to detect the presence of the front of the train just over a train length beyond the last point. NR's practce for the mainline in the UK is that the signal can be normalised almost immediately the train has passed it, but the locking is maintained on each of the points by the sectional route locking until the train has passed ver that individual point; i.e. the route becomes progressively reavailable as the train proceeeds rather than being released all simultaneously. Hence this affects many things re module 3 and aso the need for specific track joints when doing module 2.
Similarly the time value in the App Track column would need explanation but this is to me indicating "when operated" with a time out rather than the "comprehensive release" applicable to certain signals for circumstances in which there is no train that can have seen them. I think that the need for the signaller to operate a device which increments a record count in addition to the time delay would need to be stated as an assumption as this is not a requirement in the UK; the different nature of our railways probably means that route cancellation is a rare event in India that must be controlled carefully but iin the UK is reasonably frequent occurance for traffic regulation and therefore not regarded as a need to log and deter its use.
The Remarks column certainly needs quite a bit of explanation when being viewed by UK eyes. CHR would not have been regarded as meaning a Crank Handle Release and I still don't understand why there are so many nor how they would be numbered.
I am guessing the remarks such as 4RG/HG 1UG mans that signal1 has a route indicator when routed up to signal 4 and derives its aspects from that signal which is itself cabable of showing either Red or Green, but quite how this tells me what colour aspect signal 1 would itself display escapes me.
Anyway I am looking forward to seeing the various Indain attempts at 2003-
first: to get a consensus of general Indian practice,
second: to educate me,
third: to advise what to state as assumption / explanation to ensure that entries are not misinterpreted by UK eyes,
fourth: to consider whether it would be sensible to add/ amend anything (as Buddadhev was suggesting) so that the student can provide to the IRSE Examiner what they might otherwise think had been missed out
fifth: give the examiners some foretaste of what they might be presented with in some quantity next October
I deduce that the yellow aspect in India is primarily part of "speed signalling" for going into and out of loops or other turnouts etc rather than relevant to braking distance between signal posts in the "route signalling" that the UK uses. Hence it appears that my basic assumption that India would, because of its historic ties, have followed the UK rather than the European precedent is incorrect; I now guess that it may have been more based on USA or perhaps Australian practice.
The other thing that is very clear is that the locking, although with colour light signals, is actually very much that which I'd associate with "mechanical signalling" and the aspect controls seem to extend for two signal sections (i.e. in UK terminology the overlap of the signal section is in fact the entire route of the next signal section rather than to a specific defined track joint along that route). This has implications as the "exit" of the first route seems to be defined to be the line on which the 2nd signal in advance is depicted, rather than that of the exit of the route as I'd see it. I suppose the approximate equivalent in some ways of the UK Warner route is the ability at some loop signals to set a route to an exit signal with the points are set to divert any SPAD to a specifically provided overrun line and hence give the running line trapping protection.
The backlock tracks seem to be what the UK would have as sectional route locking release track circuits from the protecting signal to the last set of points in the route. This is just like mechanical practice whereby the only locking on the points is from the signal and therefore the signaller must not restore the signal lever until the last set of points have been traversed. Indeed this I believe is similar to London Underground, except that they require additional proof that the (fixed length formation but lightweigh train) has indeed cleared the area by using someother device (such as a Delta track) to detect the presence of the front of the train just over a train length beyond the last point. NR's practce for the mainline in the UK is that the signal can be normalised almost immediately the train has passed it, but the locking is maintained on each of the points by the sectional route locking until the train has passed ver that individual point; i.e. the route becomes progressively reavailable as the train proceeeds rather than being released all simultaneously. Hence this affects many things re module 3 and aso the need for specific track joints when doing module 2.
Similarly the time value in the App Track column would need explanation but this is to me indicating "when operated" with a time out rather than the "comprehensive release" applicable to certain signals for circumstances in which there is no train that can have seen them. I think that the need for the signaller to operate a device which increments a record count in addition to the time delay would need to be stated as an assumption as this is not a requirement in the UK; the different nature of our railways probably means that route cancellation is a rare event in India that must be controlled carefully but iin the UK is reasonably frequent occurance for traffic regulation and therefore not regarded as a need to log and deter its use.
The Remarks column certainly needs quite a bit of explanation when being viewed by UK eyes. CHR would not have been regarded as meaning a Crank Handle Release and I still don't understand why there are so many nor how they would be numbered.
I am guessing the remarks such as 4RG/HG 1UG mans that signal1 has a route indicator when routed up to signal 4 and derives its aspects from that signal which is itself cabable of showing either Red or Green, but quite how this tells me what colour aspect signal 1 would itself display escapes me.
Anyway I am looking forward to seeing the various Indain attempts at 2003-
first: to get a consensus of general Indian practice,
second: to educate me,
third: to advise what to state as assumption / explanation to ensure that entries are not misinterpreted by UK eyes,
fourth: to consider whether it would be sensible to add/ amend anything (as Buddadhev was suggesting) so that the student can provide to the IRSE Examiner what they might otherwise think had been missed out
fifth: give the examiners some foretaste of what they might be presented with in some quantity next October
PJW
