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Two Comments about point setting at Dorking (Not mine)

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Two Comments about point setting at Dorking (Not mine) 28/01/2019 at 21:08 #115174
bugsy
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I have just watched a video of a cab ride from Dorking towards London. The two comments below were posted in the list of comments below the video.

1. Regrettably the same error that could have prevented the accident outside Paddington. Should be locked against CBK40

2. Bad signalling practice at Dorking. Points incorrectly set before right-away.

The beginning of the video showed the points immediately in front of the train, which was waiting in platform 2, were set towards the Up line. I then saw a train leave platform 1, also in the UP direction. At first, I thought that the points for our train were incorrectly set, as per the comments above, but then I looked at the SimSig Horsham simulation and saw that in fact this set of points are interlocked with those from the Down line into platform 3 and not with those on the UP direction from platform 1. I drew my own conclusions from this, but would be interested to hear what actual signalmen have to say.

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Two Comments about point setting at Dorking (Not mine) 28/01/2019 at 21:16 #115175
KymriskaDraken
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I would have expected both ends of that crossover to be locked Reverse.


Kev

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Two Comments about point setting at Dorking (Not mine) 28/01/2019 at 21:21 #115177
GeoffM
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Signalling engineers (qualified in flank locking) would be more qualified than signallers. I am neither but after 20 years in the railway industry creating accurate sims for both real world training, and SimSig, I think I can comment.

Firstly, this scenario is virtually impossible to safely trap for the middle platform. I would argue that Ladbroke Grove - although it looks similar - is not the same as the points in question were much further apart, outside any normal distance for flank locking.

Secondly, as for why the point in front of 1D32 swinging towards the up, this is likely the path of least damage should 1D32 pass the signal at danger. It runs into a same direction / side swipe situation, instead of a head-on on the down line.

Thus, up trains can still depart P1 while a down arrives in P3, while a third is protected inside P2.

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Last edited: 28/01/2019 at 21:22 by GeoffM
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Two Comments about point setting at Dorking (Not mine) 28/01/2019 at 21:49 #115180
jc92
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I agree with Geoff. Path of least destruction, short of locking the crossover at both ends and preventing simultaneous movements from/to 1 and 3.

Also unlike Ladbroke Grove the train is unlikely to be doing anything other than moving from a standing start, arguably reducing the risk and speed of any SPAD.

Of course youtube commenter are renowned for their knowledge and experience in all railway matters, such as firing a black five over copy pit without ever making any black smoke for instance.

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Two Comments about point setting at Dorking (Not mine) 28/01/2019 at 22:32 #115181
bugsy
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GeoffM in post 115177 said:
....... as for why the point in front of 1D32 swinging towards the up, this is likely the path of least damage should 1D32 pass the signal at danger. It runs into a same direction / side swipe situation, instead of a head-on on the down line.

Thus, up trains can still depart P1 while a down arrives in P3, while a third is protected inside P2.
This is what I thought. Less damage from a side-swipe than a head-on. It looks odd at first glance though.

jc92 in post 115180 said:
I agree with Geoff. Path of least destruction, short of locking the crossover at both ends and preventing simultaneous movements from/to 1 and 3.

Also unlike Ladbroke Grove the train is unlikely to be doing anything other than moving from a standing start, arguably reducing the risk and speed of any SPAD.

Of course youtube commenter are renowned for their knowledge and experience in all railway matters.
Yes, You Tubers know about everything don’t they.

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Two Comments about point setting at Dorking (Not mine) 28/01/2019 at 23:47 #115185
clive
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GeoffM in post 115177 said:

Firstly, this scenario is virtually impossible to safely trap for the middle platform. I would argue that Ladbroke Grove - although it looks similar - is not the same as the points in question were much further apart, outside any normal distance for flank locking.
At the time of Ladbroke Grove, one of the signal engineers involved in the design posted on uk.railway. His comment was that there was a fair amount of debate as to the right way to flank lock that, but in the end they decided it was marginally better to do it the way they did rather than the other way. I forget the full reasoning, but one point is that a driver SPADing the signal had a lot longer to realize their mistake. Another was a building in the way of trapping line 3 separately.

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Two Comments about point setting at Dorking (Not mine) 29/01/2019 at 00:27 #115186
AndyG
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Maybe the overlap for the P2 up starter is across the Xover until an up train is proved at a stand in P2, then when it drops an up train can be signalled into P1. All depends on the control tables.
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Two Comments about point setting at Dorking (Not mine) 29/01/2019 at 10:36 #115189
bugsy
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AndyG in post 115186 said:
Maybe the overlap for the P2 up starter is across the Xover until an up train is proved at a stand in P2, then when it drops an up train can be signalled into P1. All depends on the control tables.

Generally, trains departing in the Up direction from platform 2 are those that have arrived from London and have terminated. They then reverse and travel back towards London. If an Up train is signalled into platform 2, which incidentally I have never seen on the sim, there is no overlap beyond the up starter CBK39, which probably means that there is a speed restriction for this manoeuvre?

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Two Comments about point setting at Dorking (Not mine) 29/01/2019 at 22:23 #115193
BarryM
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bugsy in post 115189 said:
AndyG in post 115186 said:
Maybe the overlap for the P2 up starter is across the Xover until an up train is proved at a stand in P2, then when it drops an up train can be signalled into P1. All depends on the control tables.

Generally, trains departing in the Up direction from platform 2 are those that have arrived from London and have terminated. They then reverse and travel back towards London. If an Up train is signalled into platform 2, which incidentally I have never seen on the sim, there is no overlap beyond the up starter CBK39, which probably means that there is a speed restriction for this manoeuvre?


Bugsy, All stations that have Terminating Facilities, have speed restrictions!

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Last edited: 29/01/2019 at 22:24 by BarryM
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Two Comments about point setting at Dorking (Not mine) 29/01/2019 at 23:31 #115195
headshot119
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BarryM in post 115193 said:
bugsy in post 115189 said:
AndyG in post 115186 said:
Maybe the overlap for the P2 up starter is across the Xover until an up train is proved at a stand in P2, then when it drops an up train can be signalled into P1. All depends on the control tables.

Generally, trains departing in the Up direction from platform 2 are those that have arrived from London and have terminated. They then reverse and travel back towards London. If an Up train is signalled into platform 2, which incidentally I have never seen on the sim, there is no overlap beyond the up starter CBK39, which probably means that there is a speed restriction for this manoeuvre?


Bugsy, All stations that have Terminating Facilities, have speed restrictions!
This comment is like saying, all tracks have speed restrictions. So I'm not sure what point was being made.

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Two Comments about point setting at Dorking (Not mine) 30/01/2019 at 08:52 #115198
bugsy
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headshot119 in post 115195 said:
BarryM in post 115193 said:


Bugsy, All stations that have Terminating Facilities, have speed restrictions!
This comment is like saying, all tracks have speed restrictions. So I'm not sure what point was being made.
What I was trying to explain above was that there is no overlap when an Up train is signalled into platform 2 and therefore a train’s speed has to be severely curtailed, probably more so than other routes into the station platforms which do have an overlap, although not being a railway person I could be wrong here.
Naturally, I understand that there are always speed restrictions of some sort into stations where trains are terminating as well as in other situations.
Apologies for any apparent ignorance in these matters.

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Two Comments about point setting at Dorking (Not mine) 30/01/2019 at 09:31 #115199
kbarber
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bugsy in post 115189 said:
AndyG in post 115186 said:
Maybe the overlap for the P2 up starter is across the Xover until an up train is proved at a stand in P2, then when it drops an up train can be signalled into P1. All depends on the control tables.

Generally, trains departing in the Up direction from platform 2 are those that have arrived from London and have terminated. They then reverse and travel back towards London. If an Up train is signalled into platform 2, which incidentally I have never seen on the sim, there is no overlap beyond the up starter CBK39, which probably means that there is a speed restriction for this manoeuvre?
Hmm... free yellow into P2 at CBK41, with no overlap at all at CBK39. Doesn't quite look right to me.

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