Co Acting Signals.

[mandgc]

Colin, on his DR Photo Site, shows a picture of Signal WG 3 with the label reading "WG 3 Co Acting".

Is this neccesary ? It should be self apparent and, even if it is not, this particular signal head needs to be obeyed if it is in view.

[Colin]

That reminds me - I must do a long overdue update soon.

Anyway, here's the pic for clarification:

The only purpose I can see for it is that it makes viewing of the aspect easier when looking at the monitors - though at the likes of Fulham Broadway (Eastbound), it is posible to have a small 'repeater' on top of the monitors...

[Deleted]

DD once said that the original full-size outdoor head was poorly positioned; the modern stopping mark meant that a T/Op had to crane his neck and lean forward in order to see the aspect. The new WG3 CO-ACTING signal is designed to prevent this.

JD27 CO-ACTING at Finchley Road is similar in positioning, although according to BAET it was installed as a SPAD migitation measure.

[Deleted]

mandgc said:

Is this neccesary ? It should be self apparent and, even if it is not, this particular signal head needs to be obeyed if it is in view.

I believe anywhere there are two stop signals working together at the same place on the same line, one of them has to be designated a co-acting, even if it is obvious!

After all, there can only be one actual signal in the location, and if they were both labelled as WG3 or labelled as WG3(1) and WG3(2) as some repeaters are, then technically they'd be two seperate signals which would add confusion to things like applying the rule etc.

[Deleted]

Theres also a co-acting on the Northern City branch, s/b at Euston. It's J3a - normal signal is up in right hand corner, next to the loop shunt dolly, co-acter is on left side, nicely in view...

[Tom]

theonekea said:

DD once said that the original full-size outdoor head was poorly positioned; the modern stopping mark meant that a T/Op had to crane his neck and lean forward in order to see the aspect. The new WG3 CO-ACTING signal is designed to prevent this.

Now I know a bit about this one, as a friend of mine was the designer for it. This was installed as part of a larger programme of SPAD mitigation measures in the late 1990s.

[Deleted]

But was it also installed for the reasons I mentioned?

[Deleted]

theonekea said:

But was it also installed for the reasons I mentioned?

To be honest, most coacters are installed for that reason are they not ??

[Tubeboy]

A set of co-acting signals are at the start of the Chesham branch. One theory [as to their installation] is that they replaced the single line token.

[Deleted]

tubeboy said:

A set of co-acting signals are at the start of the Chesham branch. One theory [as to their installation] is that they replaced the single line token.

Dont even go there, noone officially knows, my Duty Manager asked me once incase I knew! Its a strange one that, asthey are both on the same side too. The only thing i can imagine is that when chesham box was open you had to have a slot for both signals to clear??

[Tom]

theonekea said:

But was it also installed for the reasons I mentioned?

That was the root cause of the SPADs, yes.

[Deleted]

metapprentice said:

tubeboy said:

A set of co-acting signals are at the start of the Chesham branch. One theory [as to their installation] is that they replaced the single line token.

Dont even go there, noone officially knows, my Duty Manager asked me once incase I knew! Its a strange one that, asthey are both on the same side too. The only thing i can imagine is that when chesham box was open you had to have a slot for both signals to clear??

Actually, Harsig has said that the original setup with Chesham box open was that the advanced starter at Chesham was the signal slotted by the Chalfont IMR; the single line was thus under the control of the Amersham signalman, with the Chesham man only in control of the station area.

As for JT83 (originally JT25), it replaced a pair of semaphores in a similar configuration. Given that no single line token was used at the time (IIRC), it may have been felt that having a pair of line entry signals would give the driver a "second look" to ensure he was cleared for entry.

[Deleted]

there is a answer to this and i know the guy who has the piece of paper with it on will get it from him when i go to work and post it on here

[Tubeboy]

According to the Video 125 drivers eye view "Metropolitan main line", regarding the co acting signals, the "official reason as to their installation is not recorded". I await that piece of paper with pleasureable anticipation!

[Deleted]

all i know it was written in the late 70's from the then chief signalling engineer

[Deleted]

aetearlscourt said:

all i know it was written in the late 70's from the then chief signalling engineer

Id too would be interested to see the reason for the coacters, as AFAIK noone knew the reason.....

[DWS]

aetearlscourt said:

there is a answer to this and i know the guy who has the piece of paper with it on will get it from him when i go to work and post it on here

Lets hope he still has the piece of paper ;D

[mandgc]

Chalfont JT 83 Co-actings.

I do not think the Co-actors replaced a similar pair of Semaphores. When the Token working was withdrawn in favour of Track Circuit Control the co-actors replaced a single Starting Signal.
Two Signals were , I think, LTE's method of giving the Driver, or Train Stop, a 'Second Chance ' to stop the train. ( perhaps they didn't trust those bumped up Neasden ER Cleaners who were let loose North of Rickmansworth.) :-)

[Tom]

I think we can discount the trainstop element of that theory as there's only one trainstop.

The bit about giving the driver a second chance I could well believe, but both signals are at the same height on the same side of the line just next to each other, therefore any sighting benefit achieved by installing a co-actor is negligible.

I suspect it's going to remain one of those mysteries.

[Deleted]

mandgc said:

Chalfont JT 83 Co-actings.

I do not think the Co-actors replaced a similar pair of Semaphores. When the Token working was withdrawn in favour of Track Circuit Control the co-actors replaced a single Starting Signal.
Two Signals were , I think, LTE's method of giving the Driver, or Train Stop, a 'Second Chance ' to stop the train. ( perhaps they didn't trust those bumped up Neasden ER Cleaners who were let loose North of Rickmansworth.) :-)

My previous post was in direct reference to what you said on this subject several years ago. Naturally I can't remember where I read that a pair of co-acting semaphores were used.

Based on your info and what BAET and Harsig have stated I suspect the "second look" theory is the best one.

[Deleted]

yes the piece of paper is still there but was busy last night training new t/o's and was in the control room most of the night then signal failure this morning so never had time will get it soon but it has nothing to do with a second look theroy i asked again last night and briefly its to do with the line being single track and a token system as such deployed

i know today they have a axle counter to prove there is only one train on the branch if that helps

[Harsig]

aetearlscourt said:

i know today they have a axle counter to prove there is only one train on the branch if that helps

The axle counter was a much later installation (early 1990s) installed because of problems with the track circuits on the branch, principally during the leaf fall season.

[Deleted]

harsig said:

aetearlscourt said:

i know today they have a axle counter to prove there is only one train on the branch if that helps

The axle counter was a much later installation (early 1990s) installed because of problems with the track circuits on the branch, principally during the leaf fall season.

Was the ability to override the axle counter and send a second train onto the single line added as well?

[Deleted]

theonekea said:

Was the ability to override the axle counter and send a second train onto the single line added as well?

Not that i am aware of. To get a second train onto the branch, you would have to authorise it past a signal or two.

[mandgc]

From what I can remember, there was no explanation for the use of Co-acting Signals at the entrance to the Single Line in the Supplement to the Traffic Circular issued to Train Staff on the introduction of the Non Token Working.
My uncomplimentary reference to the Neasden ,BR, engine crews alluded to the use of 'Foreign' crews on LTE Passenger Trains. At a time of extreme Staff shortages on BR and the, perhaps, casual attitude to LTE ( 'The Hornby Railway' ) methods might have influenced LT to adopt a Belt and Braces approach.
I am not sure if Marylebone Suburban locos were fitted with Trip Cocks - The A3s from Leicester were not.

[Deleted]

ok here we go this was taken from 3rd march 1972 and if the admin would like to edit it its up to you

Mr Lawrence

Well a curious thing is, that it was on the Chesham branch and Chalfont re-signalling I first came against Mr Hadaway (chief signalling engineer). I was the drawing office man sent to work alongside him,putting right all the things that the office had done wrong in circuits. As an engineering assistant that was a formidable task, my understanding of the situation was that co-acting signals were provided because locomotive hauled trains still used the line and it was so important that the driver did not miss the aspect. If we were re-signalling the Chesham branch today we wouldn't provide these co-acting signals. Perhaps Mr Hadaway would like to add to that.

Mr Hadaway

We always had doubts about the operation of the tripcock of steam locos and this, coupled with the potential dangers of a single line, caused us to provide two signals. Whether this action ever averted a dangerous situation I wouldn't know



so theres your answer why them signals are there in the first place

[Deleted]

aetearlscourt said:

We always had doubts about the operation of the tripcock of steam locos

How does a tripcock work on a steam loco?

[agoodcuppa]

adw said:

How does a tripcock work on a steam loco?

Exactly the same as on an EMU or a Diesel.

A beam has to be attached and the tripcock valve attached to that with a connection to the vacuum brake.

[Deleted]

Well, if the driver can apply the brakes by moving a lever, then a tripcock can apply the brakes my moving a lever.

More realistically, engines on the line would have been equipped with vacuum brakes, where exhaustion of the vacuum caused emergency brake application. So the tripcock would have been arranged to have the same effect as a carriage coming off the train: STOP!!!

[Deleted]

adw said:

How does a tripcock work on a steam loco?

In the same way as it does on any other train.