What is this signal used for?

[londonmidland]

http://img163.imageshack.us/f/file0050.jpg/
The signal on the right changes at the same time as the signal on the left, anyone know why:-?
This picture was at East Midlands Parkway.

 

[90019]

I can't load the photo, so not really sure, but from the description, could it be a repeater of some sort?

 

[TomBoyRacer]

Without looking at the photo in question I assume you are referring to the Coacting signals in the down direction. They repeat the main head but are situated at ground level because the view of the main head is partially obscured by the footbridge. Hope this helps.

If I recall correctly the Signals are 4497 and 4497CA

 

[DaveNewcastle]

Looks as if that's signalling for bi-directional signalling, and the signal on the right (for 'wrong way' working) will only have red and yellow aspects; whereas the signal on the left, for right way working, has red, yellow and green aspects.
If that's true, and they both change to red simultaneously, then that will indicate that whenever the block ahead is occupied by a train, irrespective of which line is in use, no other train is permitted to occupy the parallel line.
This would apply if, for example, the two tracks combined into one just round that bend or if, for some other reason, a train occupying one track is signalled in order to prohibit the other track being occupied simultaneously, perhaps through lack of clearance.

 

[GB]

I'd say its a co-acting signal ie shows same aspect as the signal on the left to give better sighting.


I assume that station is on a curve of the main signal is obscured in some way?

 

[Darandio]

I'd say its a co-acting signal ie shows same aspect as the signal on the left to give better sighting.


I assume that station is on a curve of the main signal is obscured in some way?

Surely not when its on the other running line though? And a repeater could surely do the same job.

They are actually the penultimate signals before Trent Junction so I am not even sure they are related. What happens when a train (heading towards Trent) approaches the signal, what happens/has happened to the left hand signal?

 

[GB]

I wasn't able to open the picture at first and hence went by the description in the OP. Having now seen it it looks simply like a normal Bi-Di distant signal albeit mounted high.

 

[Darandio]

I wasn't able to open the picture. Having now seen it it looks simply like a normal Bi-Di signal.

Ah, ok.

It's the logical explanation though, especially as the next signal covers the junction and the crossovers near the river.

 

[chuffchuff]

Looking at google, I'm guessing a train leaves plat one and turns right, at the junc
and as there is not enough overlap, for the junc sig on the right hand track, the
one on plt 2 will be held at red too, so when the train has cleared the junc from
the left track clearing both overlaps, they both come off

Probably muddied the waters there

 

[londonmidland]

Thanks for replies guys! Got a little video to show you how the signals change at the same time. http://www.youtube.com/watch?v=ZZu7KPXIwX8
(Switch to 07:50 and watch in 720p in fullscreen)

 

[westcoaster]

It's actually a co-acting sig found a better pic
http://farm3.static.flickr.com/2770/4450494428_9f24cdfd6d.jpg

 

[GB]

Allthough I don't know the area, I'm going to have to go back to my orginal theory and say its a co-acting signal.

Edit: Beaten to it! Mystery solved

 

[Crossover]

My thought would be repeater, but in itself this doesn't make sense so I'd be very interested to find out its purpose.

Surely it can't be a bi-directional signal as it could potentially create two conflicting movements?

EDIT - Mystory solved - but why a co-acting signal rather than a banner repeater or such? And are there any other similar exaples anywhere else?

 

[GB]

See westcoasters post, The signal is plated CA, definitley a co acting signal

 

[westcoaster]

We had 2 CA sigs on our route, but we now only have the 1, it's located in the 6 foot in kings cross tunnel (hotel curve for those in the know), give's an extra few seconds sighting time, as there is no space for a banner repeater.

A bit on co-acting signals http://www.railsigns.co.uk/sect7page1/sect7page1.html

 

[strange6]

We had 2 CA sigs on our route, but we now only have the 1, it's located in the 6 foot in kings cross tunnel (hotel curve for those in the know), give's an extra few seconds sighting time, as there is no space for a banner repeater.

A bit on co-acting signals http://www.railsigns.co.uk/sect7page1/sect7page1.html

You learn something new every day. Didn't know these CA signals existed. They must be very rare on the network now

 

[driver9000]

There are quite a few dotted about, immediately coming to my mind are platform 14 at Manchester Piccadilly and the signal before Deansgate on the Up line (coming from Castlefield Junction heading towards Oxford Rd).

 

[144022]

is the station on a curve might be a ca signal for drivers of non stopping trains

 

[londonmidland]

is the station on a curve might be a ca signal for drivers of non stopping trains

Yes, the station is on a curve

 

[strange6]

There are quite a few dotted about, immediately coming to my mind are platform 14 at Manchester Piccadilly and the signal before Deansgate on the Up line (coming from Castlefield Junction heading towards Oxford Rd).

Not noticed them before. Will have a good look when I'm next up there

 

[142094]

How would a banner repeater located before the bend not differ from this CA signal (i.e. why wouldn't a repeater suffice)?

 

[TDK]

How would a banner repeater located before the bend not differ from this CA signal (i.e. why wouldn't a repeater suffice)?

A banner repeater cannot show the aspect - theres a co-acting signal at Coventry on the up and also one at Manchester Picadilly

 

[First class]

ML27 and ML29 3-aspect signals both have CA signals, ML27CA and ML29 respectively. A route indicator box (U or D) is provided on both the main and CA signal.

Located at Liverpool Central - Link Line.

 

[Tomnick]

The signal in question (adjacent to the Up Fast) is definitely a co-actor for the signal at the end of the Down Fast platform. A similar arrangement exists on the Slow lines (with the 'main' signal being so low that I'd imagine a crowd of passengers on the platform would almost obscure it!)

Looks as if that's signalling for bi-directional signalling, and the signal on the right (for 'wrong way' working) will only have red and yellow aspects; whereas the signal on the left, for right way working, has red, yellow and green aspects.
If that's true, and they both change to red simultaneously, then that will indicate that whenever the block ahead is occupied by a train, irrespective of which line is in use, no other train is permitted to occupy the parallel line.
This would apply if, for example, the two tracks combined into one just round that bend or if, for some other reason, a train occupying one track is signalled in order to prohibit the other track being occupied simultaneously, perhaps through lack of clearance.

I'd be concerned if the occupation of some part of line 'A' could - in the normal course of operation - replace a signal to Danger on line 'B', potentially with a train closely approaching. In that situation, both signals would need to be controlled signals, and thus the signal wouldn't be able to clear for a conflicting move on line 'A' unless the signal was proved at Danger on line 'B' (in simple terms).

 

[Kneedown]

You also get co-acting semaphore signals, with both signals mounted on one post. There was one at Hinckley when we used to sign that way, not sure if it's still there?
As regards the original signal in this thread, on the Down Slow at EM Parkway, as was stated earlier, a banner repeater would have sufficed, but cannot show the actual aspect of the signal. When the resignalling took place, it was obviously decided for whatever reason to use a co-actor instead of a repeater. Probably because of the signals close proximity to Ratcliffe junction, a co-acting signal would be more visible and attention grabbing to an approaching Driver, than a banner repeater, lost amongst the clutter of the station buildings would.
Grabbing the attention of Drivers is popular now, and is the reason that full sized signals are becoming more apparent at crossovers regularly used for turnback moves, when previously a ground position light signal would have sufficed. There's always a trade off however, and it's pretty nasty coming round the corner at night and seeing that red in front of you, even when you know full well it doesn't apply to you.

 

[ChrisCooper]

One co-acting semaphore I know of still in place is at Thetford in the Ely direction. The top signal is high to give good sighting from a distance and is over the footbridge, the second one is around eye level for drivers of trains stopped at the station (as the top arm is too high to be seen from that point). Wasn't it Rugby where there used to be a whole gantry of CA semaphores on the WCML due to the GCR bridge passing over?

More co-acting colour lights are in the tunnels approaching Birmingham New Street. CA repeaters are common in tunnels, where one signal is usually mounted on the roof and the other on the ground in the cess.

 

[bnsf734]

You also get co-acting semaphore signals, with both signals mounted on one post. There was one at Hinckley when we used to sign that way, not sure if it's still there?

No semaphores or even the box at Hinckley now. The ine was resignalled about 5 years ago I think. Croft box is the only one still used. Narborough box still exists although the crossing is controlled from Croft by CCTV.

Calv

 

[Kneedown]

One co-acting semaphore I know of still in place is at Thetford in the Ely direction.

Don't know how i forgot about that one seeing as i drive that few regulary. For some reason the one at Hinckley is the one that sticks in the mind.
--- old post above --- --- new post below ---

No semaphores or even the box at Hinckley now. The ine was resignalled about 5 years ago I think. Croft box is the only one still used. Narborough box still exists although the crossing is controlled from Croft by CCTV.

Calv

Blimey, things have changed since i last went over!

 

[londonmidland]

All of the signals on the Leicester to Birmingham New Street line are colour or LED. All the semaphore signalling have been replaced.

 

[142094]

A banner repeater cannot show the aspect - theres a co-acting signal at Coventry on the up and also one at Manchester Picadilly

But it would show that either the signal is 'on' or 'off'? Could you have a banner repeater and a CA for the same signal, or would there be no need for the banner repeater?