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| Clearing T4 24/11/2024 at 16:43 #159252 | |
OJH
11 posts |
The interlocking doesn't allow signal T4 to clear towards T6 at Truro without first lowering and clearing Truro crossing. This seems fair enough given how close T6 is to the LC and the possibility of an overrun. It doesn't look like there's any form of approach control/warner route to get around this requirement. Two things though: (a) you generally try to keep crossings down for the shortest possible time, and up trains can arrive at Truro a good 6+ minutes before they're due to leave - do we just bite the bullet and keep the crossing down for a long time to keep the driver on clear signals? (b) if an up train is stops at Truro and reverses (mainly thinking of the unit to work the first Falmouth train of the day, which can shunt via T14), the train can't be signalled into the platform without the crossing lowered anyway, even though it isn't going over it. It seems odd to lower a crossing only to raise it as soon as the interlocking drops out with nothing passing over it. Am I missing something or is this just a real-life quirk of the locking? Log in to reply |
| Clearing T4 24/11/2024 at 19:08 #159255 | |
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Stephen Fulcher
2088 posts |
It is (was) true to life. If you have six minutes before the train leaves you could keep T6 at danger and raise the barriers after the train arrives and lower again ready for departure Log in to reply The following user said thank you: OJH |
| Clearing T4 24/11/2024 at 19:08 #159256 | |
jc92
3701 posts |
It's accurate. For a train with exceptional dwell time it would be checked at the home nearly to a stand then brought into the platform against a red with the barriers down, then barriers raised. For a train booked to reverse it would equally be checked anyway as the up section isn't being cleared. The reasoning is to guard road traffic against a SPAD given the proximity of the protecting signal as you said. Worksop East had an interesting standing instruction (presumably to mitigate spads) requiring the crossing protecting signal to be cleared, and then replaced to danger when the train stopped in the up platform and barriers raised. Drivers to expect this and check the signal carefully. Exception to this being trains making brief stops. "We don't stop camborne wednesdays" Log in to reply The following users said thank you: OJH, TUT |
| Clearing T4 24/11/2024 at 19:53 #159257 | |
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Stephen Fulcher
2088 posts |
As the crossing at Truro only leads to the P-Way Depot and Station Car Park they’d likely just pull off and give the train the distant, two bridges available for pedestrians.
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| Clearing T4 24/11/2024 at 20:14 #159259 | |
Steamer
3997 posts |
Stephen Fulcher in post 159257 said:As the crossing at Truro only leads to the P-Way Depot and Station Car Park they’d likely just pull off and give the train the distant, two bridges available for pedestrians.There are a few level crossings which for whatever reason are a pain/easy to forget on SimSig. Nothing like seeing it in real life years after the sim came out and discovering it actually leads to a dead end/scrap yard/nothing at all, recall one on Sheffield in particular... "Don't stress/ relax/ let life roll off your backs./ Except for death and paying taxes/ everything in life.../ is only for now." (Avenue Q) Log in to reply |
| Clearing T4 24/11/2024 at 22:00 #159260 | |
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jc92
3701 posts |
Stephen Fulcher in post 159257 said:As the crossing at Truro only leads to the P-Way Depot and Station Car Park they’d likely just pull off and give the train the distant, two bridges available for pedestrians.I'm not sure what the penalty time is set at, but I've definitely encountered a penalty message for dropping the barriers for an up train when the approaching alarm goes off and giving him all off. after that I've perhaps been overly cautious. I didn't realise it was one of "those" crossings. Steamer - funnily enough, on Sheffield, they're almost all like that. Beighton is reasonably busy with local traffic and the only crossing that genuinely is a pain to drivers if left down. Holmes provides access to a trading estate and is regularly down 10+ mins if nothing is waiting to use it. Brinsworth street is only used by minimal traffic accessing said trading estate. I don't recall ever seeing a vehicle use it. Denaby is bypassed by a bridge and is only used for access to a Gym/Leisure centre. "We don't stop camborne wednesdays" Log in to reply |
| Clearing T4 25/11/2024 at 09:21 #159261 | |
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kbarber
1764 posts |
jc92 in post 159256 said:It's accurate. For a train with exceptional dwell time it would be checked at the home nearly to a stand then brought into the platform against a red with the barriers down, then barriers raised. For a train booked to reverse it would equally be checked anyway as the up section isn't being cleared.Is it not permissible to pull off towards a red without waiting for the train to come nearly to a stand if the train is due to stop at a platform in rear of that signal anyway? Or am I confusing it with the similar relaxation for junction signals where a train is booked to take a lower-speed turnout route? Log in to reply |
| Clearing T4 25/11/2024 at 13:36 #159262 | |
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jc92
3701 posts |
kbarber in post 159261 said:jc92 in post 159256 said:You're thinking of diverting from booked line where the turnout is a lower speed, although I beleive in some places the SBSIs have authorised a booked stopper not to be checked, its still the exception rather than the rule.It's accurate. For a train with exceptional dwell time it would be checked at the home nearly to a stand then brought into the platform against a red with the barriers down, then barriers raised. For a train booked to reverse it would equally be checked anyway as the up section isn't being cleared.Is it not permissible to pull off towards a red without waiting for the train to come nearly to a stand if the train is due to stop at a platform in rear of that signal anyway? Or am I confusing it with the similar relaxation for junction signals where a train is booked to take a lower-speed turnout route? "We don't stop camborne wednesdays" Log in to reply |
| Clearing T4 25/11/2024 at 16:40 #159265 | |
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TUT
545 posts |
Stephen Fulcher in post 159255 said:It is (was) true to life.Was it actually enforced by the interlocking or simply a requirement of the box instructions, or just mere custom and practice? The SRS provides us with a locking table that suggests it was a requirement of the interlocking, although that table is slightly dubious. https://www.s-r-s.org.uk/html/gwf/S1069.htm The GWR of course, and its successors, typically favoured what I think is called two signal locking, requiring the route to be set two signals ahead (i.e. as far as the second signal ahead, not just the next signal, wherever there was a second signal ahead of course). So it's not very surprising of a Western box. Having said that, whether it is strictly necessary is a bit debatable. As we know, road traffic passing normally over a level crossing within the clearing point is not an obstruction and a train can be accepted with the barriers up. An obstruction on the crossing, such as a road traffic accident, is a different matter, but you can quite happily allow a train to approach a home signal protecting a level crossing at full line speed with the barriers up. Despite this, it may be the custom to lower the barriers for an approaching train in time for them to be down before the train reaches the signal at danger, in case of a SPAD. I myself have worked a box where this is done. We would indeed lower the barriers for a train approaching the home signal even if there was a train standing at the section signal ahead and there was no possibility of our clearing the home signal. Once we had satisfied ourselves that the train approaching the home signal had stopped we would then raise the barriers again. On the other hand there are plenty of level crossings within overlaps which are very close to protecting signals. Pinhoe comes to mind. It is quite common for trains to approach signals protecting level crossings with the barriers in the air even if the signals are close to the crossings. Then you have TMOB crossings which of course can only be lowered by the driver (or guard or whomever) of the train approaching and cannot be lowered for that train before it gets there. Moreover, as we know, to accept a train we must have our full clearing point of a quarter of a mile or 200 yards (depending on whether the distant is a semaphore or a colour light). This is because when we accept the train it will then be signalled to travel through the block section at full speed. It will have our distant, of course, which will be displaying a caution aspect if the home is at danger, but it will then be braking from line speed and could easily overrun the signal and come into collision, hence the need of a clearing point. Once the train has been checked at the home signal, however, and we are sure that the speed is under control, we can then move it down from signal to signal within our station limits, checking the speed at each signal in turn. Semaphore signals in station limits do not typically have overlaps. They don't need them. You can quite happily clear a stop signal to allow a train up to the next signal (provided that train has been stopped or nearly stopped at the first signal) even with another train 2 feet beyond the next signal. You don't need 200 yards, you certainly don't need a quarter of a mile, you don't need anything, you're in control within your garden and the speeds are under control. Now an exception to the above, of course, is junctions and that includes conflicting or converging movements over any points or crossovers or anything like that. You are forbidden, essentially, to allow a train to approach the signal protecting a crossing or conflicting movement. You have to hold it back at the previous one until the movement is clear or has stopped. As I say this is typically enforced by the interlocking in Western boxes and that makes sense because a sideswipe would be very serious indeed. Also you'd have a train signalled across the bows of another, meaning that a driver braking for a signal and possibly slightly misjudging it might be horrified to find a movement cutting across his path from one side or another. Whereas if the signal is protecting a train standing just beyond the signal, an approaching driver will clearly be able to see both the obstruction and the signal protecting it and in the event of a low-speed collision it will be much less severe than a side swipe. Not really sure why the level crossing at Truro should be considered in the side swipe category instead of the train full of passengers stopped 2 feet beyond the signal ahead category in terms of risk. Bearing in mind when it comes to clearing points a train full of passengers 2 feet beyond the home signal is an obstruction. Road traffic isn't. Log in to reply |
| Clearing T4 25/11/2024 at 17:29 #159266 | |
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TUT
545 posts |
kbarber in post 159261 said:jc92 in post 159256 said:I'm sure that was a rule at some time in some place as well, but I can't now find any reference to it.It's accurate. For a train with exceptional dwell time it would be checked at the home nearly to a stand then brought into the platform against a red with the barriers down, then barriers raised. For a train booked to reverse it would equally be checked anyway as the up section isn't being cleared.Is it not permissible to pull off towards a red without waiting for the train to come nearly to a stand if the train is due to stop at a platform in rear of that signal anyway? Or am I confusing it with the similar relaxation for junction signals where a train is booked to take a lower-speed turnout route? It is not the case today, however. The rule in full is Quote: If you cannot clear a stop signal, you must not clear any associated signals on the approach to it until the train has stopped or nearly stopped at each signal in turn.There are no other general exceptions to this rule. However, the Sectional Appendix (surely not just the SBSIs as drivers must clearly understand the meaning of all signals they will encounter) may allow this as an exception. Worcester Shrub Hill is an interesting example where this is the case. It is the only exception left on the entire LNW South route. The Up Branch Homes may be cleared for a train to enter either platform before an approaching train has stopped (or nearly stopped), even though following signals may be at danger. This indeed applies to stopping trains only. The Up Main Home also used to be included in the list, but that is now an approach controlled colour light, so it no longer makes any sense to include it. Interestingly there is one more signal on the list for Worcester Shrub Hill and that is its Down Main Home: SH83. SH83 may be cleared without checking an approaching train even though the following signals may be at danger, but again only if that train is booked to stop at Shrub Hill Station. SH83 does not signal trains into the station - that is the Down Main Inner Home: SH82. SH82 does not appear on the list of exceptions. SH83 is a most interesting signal. It is fitted with a fixed distant below it which applies to the rest of Shrub Hill's Down Main signals. It also cannot be cleared unless the overlap of the semaphore Down Main Inner Home signal SH82 is clear (SH82 being unusual in having an overlap (it's about 150 yards in length)). SH83 also has its own distant - SH84 - a colour light which will show single yellow if SH83 is on and double yellow if SH83 is off (double yellow as SH83 has a fixed distant of course, so SH83 is almost like a semaphore equivalent of a single yellow). One interesting thing is that the March 2021 LNW South instruction does include the remark that the ability to clear all of these signals without checking an approaching train applies to stopping trains only. The September 2014 Western instruction does not include any remark limiting the ability to clear any of these signals without checking an approaching train. Log in to reply |
| Clearing T4 25/11/2024 at 17:32 #159267 | |
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jc92
3701 posts |
There's a precedent for this type of locking in power schemes as well. Tipton and Worksop being two that spring to mind. Off the top of my head Worksop has the signal in rear approach controlled to red to check the trains speed, while Tipton requires/required Watery lanes slots with the barriers down and locked to get any proceed aspect.
"We don't stop camborne wednesdays" Log in to reply The following user said thank you: TUT |
| Clearing T4 25/11/2024 at 18:27 #159268 | |
pedroathome
916 posts |
So, the modern day signals which have replaced T4 and T14 (Former T14 now being main aspect), both require that Truro crossing is down and clear before getting an aspect into either Platforms 2 or 3. I can't think of anywhere where a protecting signal is as close to a crossing as Truro is. Lostwithiel on the Up has the protecting signal now on the approach to the station. Log in to reply |
| Clearing T4 25/11/2024 at 19:59 #159270 | |
lazzer
636 posts |
Stephen Fulcher in post 159257 said:As the crossing at Truro only leads to the P-Way Depot and Station Car Park they’d likely just pull off and give the train the distant, two bridges available for pedestrians.I can confirm that in the days of the semaphores this was indeed the case. Unless there was a reason for the signaller to have any of the signals at danger (the level crossing not being one of them), then you would always see the Up Distant at green, and the barriers down when you come round the corner and sighted it at the end of the platform, with T6 off. There would often be maybe one or two cars or a truck waiting to leave the car park, and inevitably the odd person. Now we have the Mid Cornwall panel controlling things, they can lower the crossing slightly later than before, given that there is no distant signal to consider the driver seeing at green. But even so, the barriers are always down on arrival, as before. Log in to reply The following user said thank you: OJH |
| Clearing T4 26/11/2024 at 15:11 #159272 | |
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Zoe
258 posts |
lazzer in post 159270 said:As the crossing at Truro only leads to Now we have the Mid Cornwall panel controlling things, they can lower the crossing slightly later than before, given that there is no distant signal to consider the driver seeing at green. But even so, the barriers are always down on arrival, as before. The Up Main Distant (T2) could show green if the Up Main Home (T3) was yellow though. Is 5916 in a different location to the old T3? Last edited: 26/11/2024 at 15:11 by Zoe Reason: None given Log in to reply |
| Clearing T4 26/11/2024 at 16:40 #159273 | |
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bill_gensheet
1432 posts |
jc92 in post 159267 said:There's a precedent for this type of locking in power schemes as well. Tipton and Worksop being two that spring to mind. Off the top of my head Worksop has the signal in rear approach controlled to red to check the trains speed, while Tipton requires/required Watery lanes slots with the barriers down and locked to get any proceed aspect.Sawbridgeworth on West Anglia sim allows trains up to the crossing without lowering it, up direction makes more sense as the platforms are that side. A fairly busy road and the distance from signals to crossing is at most 2 coaches worth. Not sure if it has changed lately and needs the crossing to arrive, a while since I have had to go over there. Log in to reply |
| Clearing T4 26/11/2024 at 17:40 #159275 | |
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Stephen Fulcher
2088 posts |
Zoe in post 159272 said:lazzer in post 159270 said:T2 was a long way from T3, and T3 was approach release from red unless the road was set all the way to Probus.As the crossing at Truro only leads to Now we have the Mid Cornwall panel controlling things, they can lower the crossing slightly later than before, given that there is no distant signal to consider the driver seeing at green. But even so, the barriers are always down on arrival, as before. The reason you could not approach T6 (and LL5 at Lostwithiel) with the barriers up is that the signal was only about ten feet from the crossing so by the time the interlocking had reacted in the event of a SPAD you’d have a train well onto the crossing before the road lights started. Log in to reply The following user said thank you: TUT |
| Clearing T4 26/11/2024 at 18:10 #159276 | |
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Zoe
258 posts |
Stephen Fulcher in post 159275 said:As the crossing at T2 was a long way from T3, and T3 was approach release from red unless the road was set all the way to Probus. There was a discussion about this elsewhere about 15 years ago and I do seem to remember an S&T tech detailing a circumstance where there could be a free yellow (possibly involving certain track circuits being clear) but also that there were changes to this arrangement at some point. Unfortunately the old version of that forum got closed quite a few years back and none of the old posts survive. Last edited: 26/11/2024 at 18:15 by Zoe Reason: None given Log in to reply The following user said thank you: TUT |
| Clearing T4 26/11/2024 at 18:33 #159277 | |
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jc92
3701 posts |
Stephen Fulcher in post 159275 said:Zoe in post 159272 said:Assuming NE wales is accurate, Gobowen is the opposite. Protecting signal almost on top of the crossing but an approaching train gets YY-Y-R on approach with no controls. Presumably the short distance there is considered sufficient to at least start the lights flashing?lazzer in post 159270 said:T2 was a long way from T3, and T3 was approach release from red unless the road was set all the way to Probus.As the crossing at Truro only leads to Now we have the Mid Cornwall panel controlling things, they can lower the crossing slightly later than before, given that there is no distant signal to consider the driver seeing at green. But even so, the barriers are always down on arrival, as before. "We don't stop camborne wednesdays" Log in to reply |
| Clearing T4 26/11/2024 at 20:18 #159279 | |
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Stephen Fulcher
2088 posts |
Zoe in post 159276 said:Stephen Fulcher in post 159275 said:There’s a good chance that could have been me and you’ve got me thinking now so I will check and confirm one way or the other.As the crossing at T2 was a long way from T3, and T3 was approach release from red unless the road was set all the way to Probus. Log in to reply |
| Clearing T4 26/11/2024 at 20:18 #159280 | |
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Stephen Fulcher
2088 posts |
Zoe in post 159276 said:Stephen Fulcher in post 159275 said:There’s a good chance that could have been me and you’ve got me thinking now so I will check and confirm one way or the other.As the crossing at T2 was a long way from T3, and T3 was approach release from red unless the road was set all the way to Probus. Log in to reply |
| Clearing T4 26/11/2024 at 20:22 #159281 | |
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Stephen Fulcher
2088 posts |
jc92 in post 159277 said:Stephen Fulcher in post 159275 said:I have attached three Google screenshots.Zoe in post 159272 said:Assuming NE wales is accurate, Gobowen is the opposite. Protecting signal almost on top of the crossing but an approaching train gets YY-Y-R on approach with no controls. Presumably the short distance there is considered sufficient to at least start the lights flashing?lazzer in post 159270 said:T2 was a long way from T3, and T3 was approach release from red unless the road was set all the way to Probus.As the crossing at Truro only leads to Now we have the Mid Cornwall panel controlling things, they can lower the crossing slightly later than before, given that there is no distant signal to consider the driver seeing at green. But even so, the barriers are always down on arrival, as before. Whilst it does not appear to be far, Gobowen is significantly further back from the crossing than Truro or Lostwithiel. You can see the IRJ between the signal and the crossing which would be the start of the track circuit that would set off the lights in the event of a SPAD. Truro the joint is the other side of the road, and Lostwithiel from memory wasn’t even track circuited. Before the invention of the Moreton-on-Lugg modifications to both crossings it was possible to replace the preceding signal and raise the barriers straight away. After Moreton the requirement for a timeout was introduced.    Post has attachments. Log in to view them. Log in to reply The following user said thank you: jc92 |
| Clearing T4 26/11/2024 at 20:28 #159282 | |
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lazzer
636 posts |
Zoe in post 159272 said:lazzer in post 159270 said:No, it's more or less in the same place.As the crossing at Truro only leads to Now we have the Mid Cornwall panel controlling things, they can lower the crossing slightly later than before, given that there is no distant signal to consider the driver seeing at green. But even so, the barriers are always down on arrival, as before. Log in to reply |