28-08-2010, 12:47 PM
Some additional comments of the layout, which wa broadly quite reasonable..
1. Since Freight branch only has one train an hour, then isolated 3 aspect (stop and distant) signalling would be appropriate. Only need a headway signal every 10-20km or so (even that would give much more capacity than required for the timetabled trains) so continuous 3 aspects excessive.
2. You should always show, not to scale (bitdimension them), the "next" / "previous" signal at the very limits of the area, at A, B, G and H on this layout. Because of the absence of one on the Up Main at B I am unclear what you are seeking to achive by the blanked top aspect for 110 signal.
3. You haven'y consistently marked the signal spacing.Where you have it is good; I can readily see that you have brought 128 in as close to the station as you can and positioned 134 so theat the minimum braking is still achieved and complied with the one-third/two-thirds rule but a note to that effect would probably habve been wise.Since you haven't shown a signal at F though I can't see what your plans were for this section.
You have indicated at 113 signal a distance of 1975m (full braking) but this confuses as it is a 4 aspect signal. In reality I think you have placed it about 1000m in rear of signal 119 which is itself around 2000m in rear of signal 125 with signal 121 deliberately off centre, but I haven't spent the time making all the measurements.
4. Junction C looks sensible, but GPL 114 is superfluous. In other layouts there could hae been a need to have split both CG and DS tracks into two portions but given the use of this infrastructure here than I think sensible to do precisely what you have done.- it isnt worth spending the extra money. Also see 8.
5. Not sure why you have signal 1119 as controlled but plated as Automatic; I'd have had just as an Auto.
6. As mentioned in route boxes, I don't feel you needed to provide PL moves into the station pl;atforms; suggest that if you feel a layout warrants them but the wording doesn't explicitly require provision then you put a note to justify why provided.
7. Station D looks good, except that the ROL beyond 125 is superfluous. The Down May should have been given red bufferstop light and trap points 22A would not normally be provide given the declared usage of that platform- however historically bays did have and often still retain such trap points so this is certaainly not wrong. Conversely for the Up siding this does require so you were correct to provide; not the IRSE don't show traps and expect you to show them when needed.
8. You certainly should have showed that you considered them at the junction of the Goods Line; traditionally these would have needed but given that the line is being signalled to passenger standards for fully fitted trains which evidentally run at reasonable speeds it would be entirely reasonable to modern practice not to provide. HOWEVER you should have put a note to that effect in the vicinity of the junction to ensure examiner aware of your thought process leading to non-provision. Ironically the place where your utilisation proposes to leave a train of wagons on the running line is beyond the junction and you need to think about that. I suggest that the guard of the train would have uncoupled the loco and then be walking down the length of the train to be ready to couple up the loco when it has run around via 225 points so the train is not completely unattended and will only be left without a locomotive for some 20 minutes and there is no other traffic at that time so the isk is minimal.
[Did you hear about the very scary incident recently where an engineering train on the London Underground Northern Line somehow managed to go careering along the line without anyone on board catching up an early morning passenger train? This was warned and therefore the driver asked passengers to vacate the rear carriage and the train continued non-stop through several stations before getting beyond a junction which was switched to the other lie to divert the runaway along another branch with some 45 seconds to spare. Sounds like something from the movies representing the early "wild-west days" of railways rather than real life in London in 2010, but just goes to show that these things can still occur....]
9. When putting a LOS etc on the layout often worth depicting the length of train for which standage is provided. Looks to me that you only intend it for trains of the length that fit into the Up Sding or Down bay and you are not proposing to propel a 400m long freight towards it- this is fine but some additional clarity would have been useful.
Seeing as they are so close then would have been better to have put signal 126 opposite 128. You don't need CU track; could have made all part of CV and it would not have mattered if this was much longer than 180m- a longer overlap makes little difference to headway and in this case we are not even worried about following trains at all.
10. The branch wsa pretty good attempt- there may be some quibbles re the treadle needing to be directional ad positioned just beyond 130 signal, but in the scheme of things not worth worrying about. There would not be a treadle or track circuit at station G though- the whole essence is that there is no "acive" signalling along such a line, just notice boards and appropriate to very basic railway with no other infrastructure. Nowadays not likely to provide OTW-NS since technology has moved on and being able to get some form of communications to such places and encode so that safety critical information can be passed is now a practicable possibility and I think we can assume that there will be a mains supply to the domestics at the station which could be used to feed a UPS. I understand that the Siemens axle counter installed on the Settle and Carlise recently has the bility to operate some miscellaneous output devices so perhaps the modern solution to such a line is to instal one of these. Hence the line could be track circuit block, you could have your EC section at virtually no cost and replace the noticeboard with a Red/Green signal fed from the axle counter unit and communications. Rather spoils things for the IRSE examiner perhaps but definitely a better solution! Provided that you explained how it was cost effective to provide such facility then you'd have fulfilled the exam requirements.
Approaching junction E then with 130 being MAR then 132 might as well be a fixed yellow or even reflectorised distant board. Alternatively if 130 not MAR then may have been worth extending EB track sufficiently on the approach to 132 that the signaller would have time to respond to its occupancy to clear 130 priro to the driver passing 132 and thus get some benefit from it's Green aspect.
I imagine that you have already looked at the other attempt at this layout and read the commentsthere; if not worth doing so now. Feel free to ask anything that I have not covered adequately.
1. Since Freight branch only has one train an hour, then isolated 3 aspect (stop and distant) signalling would be appropriate. Only need a headway signal every 10-20km or so (even that would give much more capacity than required for the timetabled trains) so continuous 3 aspects excessive.
2. You should always show, not to scale (bitdimension them), the "next" / "previous" signal at the very limits of the area, at A, B, G and H on this layout. Because of the absence of one on the Up Main at B I am unclear what you are seeking to achive by the blanked top aspect for 110 signal.
3. You haven'y consistently marked the signal spacing.Where you have it is good; I can readily see that you have brought 128 in as close to the station as you can and positioned 134 so theat the minimum braking is still achieved and complied with the one-third/two-thirds rule but a note to that effect would probably habve been wise.Since you haven't shown a signal at F though I can't see what your plans were for this section.
You have indicated at 113 signal a distance of 1975m (full braking) but this confuses as it is a 4 aspect signal. In reality I think you have placed it about 1000m in rear of signal 119 which is itself around 2000m in rear of signal 125 with signal 121 deliberately off centre, but I haven't spent the time making all the measurements.
4. Junction C looks sensible, but GPL 114 is superfluous. In other layouts there could hae been a need to have split both CG and DS tracks into two portions but given the use of this infrastructure here than I think sensible to do precisely what you have done.- it isnt worth spending the extra money. Also see 8.
5. Not sure why you have signal 1119 as controlled but plated as Automatic; I'd have had just as an Auto.
6. As mentioned in route boxes, I don't feel you needed to provide PL moves into the station pl;atforms; suggest that if you feel a layout warrants them but the wording doesn't explicitly require provision then you put a note to justify why provided.
7. Station D looks good, except that the ROL beyond 125 is superfluous. The Down May should have been given red bufferstop light and trap points 22A would not normally be provide given the declared usage of that platform- however historically bays did have and often still retain such trap points so this is certaainly not wrong. Conversely for the Up siding this does require so you were correct to provide; not the IRSE don't show traps and expect you to show them when needed.
8. You certainly should have showed that you considered them at the junction of the Goods Line; traditionally these would have needed but given that the line is being signalled to passenger standards for fully fitted trains which evidentally run at reasonable speeds it would be entirely reasonable to modern practice not to provide. HOWEVER you should have put a note to that effect in the vicinity of the junction to ensure examiner aware of your thought process leading to non-provision. Ironically the place where your utilisation proposes to leave a train of wagons on the running line is beyond the junction and you need to think about that. I suggest that the guard of the train would have uncoupled the loco and then be walking down the length of the train to be ready to couple up the loco when it has run around via 225 points so the train is not completely unattended and will only be left without a locomotive for some 20 minutes and there is no other traffic at that time so the isk is minimal.
[Did you hear about the very scary incident recently where an engineering train on the London Underground Northern Line somehow managed to go careering along the line without anyone on board catching up an early morning passenger train? This was warned and therefore the driver asked passengers to vacate the rear carriage and the train continued non-stop through several stations before getting beyond a junction which was switched to the other lie to divert the runaway along another branch with some 45 seconds to spare. Sounds like something from the movies representing the early "wild-west days" of railways rather than real life in London in 2010, but just goes to show that these things can still occur....]
9. When putting a LOS etc on the layout often worth depicting the length of train for which standage is provided. Looks to me that you only intend it for trains of the length that fit into the Up Sding or Down bay and you are not proposing to propel a 400m long freight towards it- this is fine but some additional clarity would have been useful.
Seeing as they are so close then would have been better to have put signal 126 opposite 128. You don't need CU track; could have made all part of CV and it would not have mattered if this was much longer than 180m- a longer overlap makes little difference to headway and in this case we are not even worried about following trains at all.
10. The branch wsa pretty good attempt- there may be some quibbles re the treadle needing to be directional ad positioned just beyond 130 signal, but in the scheme of things not worth worrying about. There would not be a treadle or track circuit at station G though- the whole essence is that there is no "acive" signalling along such a line, just notice boards and appropriate to very basic railway with no other infrastructure. Nowadays not likely to provide OTW-NS since technology has moved on and being able to get some form of communications to such places and encode so that safety critical information can be passed is now a practicable possibility and I think we can assume that there will be a mains supply to the domestics at the station which could be used to feed a UPS. I understand that the Siemens axle counter installed on the Settle and Carlise recently has the bility to operate some miscellaneous output devices so perhaps the modern solution to such a line is to instal one of these. Hence the line could be track circuit block, you could have your EC section at virtually no cost and replace the noticeboard with a Red/Green signal fed from the axle counter unit and communications. Rather spoils things for the IRSE examiner perhaps but definitely a better solution! Provided that you explained how it was cost effective to provide such facility then you'd have fulfilled the exam requirements.
Approaching junction E then with 130 being MAR then 132 might as well be a fixed yellow or even reflectorised distant board. Alternatively if 130 not MAR then may have been worth extending EB track sufficiently on the approach to 132 that the signaller would have time to respond to its occupancy to clear 130 priro to the driver passing 132 and thus get some benefit from it's Green aspect.
I imagine that you have already looked at the other attempt at this layout and read the commentsthere; if not worth doing so now. Feel free to ask anything that I have not covered adequately.
PJW