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Control tables question

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Control tables question 07/03/2018 at 22:09 #106541
clive
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I've acquired some old control tables from the Eastern Region. There are some things in them that don't make sense to me, so I'm wondering if anyone here can help.

The routes tables have footnotes:
R/A - Route Away
O/C - Once Signal Cleared

One route has, in the "signal controls, track circuits clear" column, among other entries that make sense:
(1234 or 2345R or R/A) (1111 or OCC)
Track circuit 1111 is the first one in the route, but it makes no sense to me to say that the track circuit must be occupied or clear; why not just leave it out of the table? Track circuit 1234 makes sense as a flank protection when 2345 points are normal, but what is the "Route Away" bit about? That one's just an example; there are other similar ones.

Can anyone help?

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Control tables question 07/03/2018 at 22:19 #106542
Sacro
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Initial track occupied or clear usually suggests last wheel replacement.
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Control tables question 10/03/2018 at 07:24 #106578
TomOF
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Agreed.

The signal won’t clear if the first track beyond the signal is occupied but a stick path in the relay circuitry will be energised when the signal steps up from red allowing the signal to remain off. The only note of caution is to check whether this applies to all tracks in line of route or just the first. Westbury station platform starter signals appear to have third track replacement rather than last wheel.

The route away bit refers to a check in the aspect level for other nearby tracks clear that could suggest an overrun has taken place and revert the signal to danger. An exemption to this rule is a check for the USR down in a direction that would positively take a train away from our route, not towards it hence the route away part. I’ve implemented this at Carlisle in a couple of places.

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Control tables question 10/03/2018 at 10:23 #106583
clive
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TomOF in post 106578 said:


The signal won’t clear if the first track beyond the signal is occupied but a stick path in the relay circuitry will be energised when the signal steps up from red allowing the signal to remain off. The only note of caution is to check whether this applies to all tracks in line of route or just the first. Westbury station platform starter signals appear to have third track replacement rather than last wheel.
In this case 1111 is in the "disengage" column as well. So, while I see what you're saying, I'm not clear if that still applies. The "OR OCC" stuff is only on the first track circuit, and second track circuit replace does make a bit of sense to me.

TomOF in post 106578 said:

The route away bit refers to a check in the aspect level for other nearby tracks clear that could suggest an overrun has taken place and revert the signal to danger. An exemption to this rule is a check for the USR down in a direction that would positively take a train away from our route, not towards it hence the route away part. I’ve implemented this at Carlisle in a couple of places.
Okay, that makes a lot of sense given the data. Thanks.

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Control tables question 10/03/2018 at 11:20 #106588
TomOF
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clive in post 106583 said:
[quote=TomOF;post=106578]
In this case 1111 is in the "disengage" column as well. So, while I see what you're saying, I'm not clear if that still applies. The "OR OCC" stuff is only on the first track circuit, and second track circuit replace does make a bit of sense to me.
If I recall correctly is effectively a check for track occupied after the signal clears.
This prevents the signal re-clearing unless restroked with the disengaging track clear (or auto button selected).

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Control tables question 10/03/2018 at 17:25 #106608
GeoffM
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2nd track replacement was a common fudge when TPWS was introduced, to prevent the toast rack arming with the signal now back at red before the sensor on the train passed the rack.
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Control tables question 12/03/2018 at 20:47 #106697
Firefly
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Quote:
In this case 1111 is in the "disengage" column as well. So, while I see what you're saying, I'm not clear if that still applies. The "OR OCC" stuff is only on the first track circuit, and second track circuit replace does make a bit of sense to me.
1111 being in the disengaging column is not really relevant to the track circuits in aspect conditions. The number of tracks that have OR OCC (called $40 controls on modern control tables) will usually depend on the reason for applying last wheel replacement. If it's just for TPWS as Geoff has mentioned then you would only need the first track past the signal, if however it's to allow a propelling move to take place then you would include all track circuits to accommodate the longest train. On the scheme that I'm presently testing they've made an allowance for 700m trains (for some bizarre reason), therefore signals that have last wheel replacement have $40 controls on all track circuits that fall 700m beyond the signal.

You can't just ignore those track circuits because if you had a light engine sat 600m down the line you mustn't allow the signal to clear. However, once you've proved that all of your track circuits beyond the signal are clear and you have a proceed aspect, then those tracks can be either occupied or clear. In reality there are a few more conditions. I may have managed to attach some images to help explain.

FF
[attachment=9399]Screen Shot 2018-03-12 at 20.45.40.png[/attachment]

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Last edited: 12/03/2018 at 22:04 by Firefly
Reason: None given

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Control tables question 13/03/2018 at 00:52 #106719
BarryM
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Is it not bizarre when you have some Australian train over 1000m long?

Barry

Barry, Sydney, New South Wales, Australia
Last edited: 13/03/2018 at 00:54 by BarryM
Reason: .

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Control tables question 13/03/2018 at 09:16 #106725
Firefly
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Yes, but not on some back water line in the U.K.
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Control tables question 13/03/2018 at 09:24 #106726
postal
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BarryM in post 106719 said:
Is it not bizarre when you have some Australian train over 1000m long?

Barry
What is bizarre is boasting about trains over 1000m long when that is kiddy-car railway compared to some.

Have a look at this page from July 2017 extracted at random from t'internet. It includes:

"CSX, the No.3 U.S. railroad by revenue, told investors in October its freight trains have increased more than 400 feet to 6,833 feet (2.08 km) on average since March, when newly appointed Chief Executive Officer Hunter Harrison launched his plan to boost profits and streamline operations."

So if 2080m. is the average, heaven knows what their longest consist runs to.

"It is a most mortifying reflection for a man to consider what he has done, compared to what he might have done." - Samuel Johnson, English author, 18/09/1709 - 13/12/1784
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