• Our new ticketing site is now live! Using either this or the original site (both powered by TrainSplit) helps support the running of the forum with every ticket purchase! Find out more and ask any questions/give us feedback in this thread!

125mph with 3-aspect colour light signalling

Status
Not open for further replies.

ComUtoR

Established Member
Joined
13 Dec 2013
Messages
9,562
Location
UK
I think it should be pointed out that while trainstops cannot prevent SPADs

There has been a change in the trainstops at London Bridge where the trainstop is provided before the signal, not at it. This should prevent a SPAD. Is this a new standard or just something unique to the London Bridge installations ?

Has anyone else ever noticed a coloured light signal 'winking' once as though the signaller
We were informed that it is part of the self testing. We get loads that 'blink' (including banners) and it got reported and that was the information that was sent out. You certainly stick the brakes in the first time you see it happen.
 
Sponsor Post - registered members do not see these adverts; click here to register, or click here to log in
R

RailUK Forums

Warwick

Member
Joined
10 Apr 2018
Messages
353
Location
On the naughty step again.
...so are these things red railway signals that can actually be passed at danger without a calling on aspect? Just a note that it is a repeater - which must be unique to LU! I believe BR introduced banner repeaters precisely so that there would never be a situation where a conventional signal was passed at danger without a special authorisation.

Authorisation to pass a red signal has existed for donkey's years. It's called a subsidiary signal. Banner repeater are nothing whatsoever to do with authorising a red signal to be passed.
 

Warwick

Member
Joined
10 Apr 2018
Messages
353
Location
On the naughty step again.
I've had a message - anonymously, how brave of someone - to say that a post that I put on this thread has been deleted due to "provocation". Anyone care to elucidate? I'm not aware of provoking anyone.
 

Tomnick

Established Member
Joined
10 Jun 2005
Messages
5,933
Has anyone else ever noticed a coloured light signal 'winking' once as though the signaller might have re-set the signal but to the same aspect it was already showing? LED type. Like the colour disappears for about .2 of a second but is then seen again? Or could this be a faulty signal? Note not seen this when a train has been anything within 3 mins of a signal.
We were informed that it is part of the self testing. We get loads that 'blink' (including banners) and it got reported and that was the information that was sent out. You certainly stick the brakes in the first time you see it happen.
That's my understanding too. I can't think that it's anything to do with the signalman's actions - you couldn't pull the route and reset it quickly enough to avoid it visibly returning to danger (and I've seen it happen on auto signals too).
There has been a change in the trainstops at London Bridge where the trainstop is provided before the signal, not at it. This should prevent a SPAD. Is this a new standard or just something unique to the London Bridge installations ?
Is this from the bay platforms? We have at least one dead-end platform with additional trainstop loops about 80m back from the signal, but that's to ensure that a short train (so having more room to get a run up!) is stopped before the conflict point which isn't far beyond the signal, rather than about preventing a SPAD in the first place.
 

ComUtoR

Established Member
Joined
13 Dec 2013
Messages
9,562
Location
UK
Blackfriars has additional TPWS in the bays (tripped recently) but I'm talking about the starters in the through platforms. There was a lot of Drivers pulling short as there is a serious issue when stopping over grids. I forget how far they are in front of the signal but they look like they are placed so starting against the Red will stop the train before it hit the signal. There is an internal brief stating exactly how far in front they are. Conversely the trainstop at Bromly South is actually behind the signal by about 20m. Placed to protect the conflict point but you would be well past the signal :/
 

MarkyT

Established Member
Joined
20 May 2012
Messages
7,573
Location
Torbay
There has been a change in the trainstops at London Bridge where the trainstop is provided before the signal, not at it. This should prevent a SPAD. Is this a new standard or just something unique to the London Bridge installations ?
I was really referring to LU mechanical trainstops but Tomnick answers the question.
Is this from the bay platforms? We have at least one dead-end platform with additional trainstop loops about 80m back from the signal, but that's to ensure that a short train (so having more room to get a run up!) is stopped before the conflict point which isn't far beyond the signal, rather than about preventing a SPAD in the first place.
 

MarkyT

Established Member
Joined
20 May 2012
Messages
7,573
Location
Torbay
Blackfriars has additional TPWS in the bays (tripped recently) but I'm talking about the starters in the through platforms. There was a lot of Drivers pulling short as there is a serious issue when stopping over grids. I forget how far they are in front of the signal but they look like they are placed so starting against the Red will stop the train before it hit the signal. There is an internal brief stating exactly how far in front they are. Conversely the trainstop at Bromly South is actually behind the signal by about 20m. Placed to protect the conflict point but you would be well past the signal :/

Areas around platforms often get additional loops, sometimes additional overspeeds are provided when the signal is a fair way from the stopping point in a through platform.
 

Mojo

Forum Staff
Staff Member
Administrator
Joined
7 Aug 2005
Messages
21,180
Location
0035
I think it should be pointed out that while trainstops cannot prevent SPADs, LU's practice of providing a fully braked overlap beyond each signal prevents any such SPAD leading to a junction collision.
True, although I’m aware of a location where the trainstop is located a big enough distance before the associated signal that it is possible for the train to be tripped before the signal is passed. I know of one such incident at this location that was “downgraded” to a staff error from what was initially reported as a SPAD!
No, they are yellow green, sometime with "F" superimposed on the yellow, so they are distant signals in the usual language, but also repeaters as they exactly repeat the stop signal to which they apply, albeit with different colours.
For completeness, repeaters that are co-located with ordinary stop signals are blank if the stop signal is displaying a danger aspect; this is to avoid displaying conflicting meanings. Repeaters can also apply to multiple signals, and don’t always apply to the following signal, the so might be showing a yellow but the next running signal after the repeater is green.
 

ComUtoR

Established Member
Joined
13 Dec 2013
Messages
9,562
Location
UK
@MarkyT

Just for clarification. I'm specifically referring to the ones out London End of Platforms 8/9 at London Bridge which are placed about 10m before the Red. As London Bridge is a new installation I' wondering if this is a new standard for trainstop (TPWS) placement. It's a much better placement and should prevent a SPAD.

*edit*

HL17 briefing mentions TPWS grids provided more than 4m on the approach to the following signals to comply with signalling standards.
 
Last edited:

AndrewE

Established Member
Joined
9 Nov 2015
Messages
7,345
Authorisation to pass a red signal has existed for donkey's years. It's called a subsidiary signal. Banner repeater are nothing whatsoever to do with authorising a red signal to be passed.
Correct, I know that, which is why I asked "are these things red railway signals that can actually be passed at danger without a calling on aspect?" A banner repeater horizontal says the next signal (that you can't yet see) is not showing clear, avoiding the conflict of it not being an actual signal yet needing to show that a red might be coming up (which cannot be passed.)
 

edwin_m

Veteran Member
Joined
21 Apr 2013
Messages
28,665
Location
Nottingham
Has anyone else ever noticed a coloured light signal 'winking' once as though the signaller might have re-set the signal but to the same aspect it was already showing? LED type. Like the colour disappears for about .2 of a second but is then seen again? Or could this be a faulty signal? Note not seen this when a train has been anything within 3 mins of a signal.
If this is on a video then it may be due to the LEDs (some types of which actually flash on and off too fast to see) interacting with the frame rate of the camera.
 

Mojo

Forum Staff
Staff Member
Administrator
Joined
7 Aug 2005
Messages
21,180
Location
0035
Correct, I know that, which is why I asked "are these things red railway signals that can actually be passed at danger without a calling on aspect?" A banner repeater horizontal says the next signal (that you can't yet see) is not showing clear, avoiding the conflict of it not being an actual signal yet needing to show that a red might be coming up (which cannot be passed.)
No, they display yellow or green aspects (or are blank when co-located with a stop signal displaying a danger aspect).
 

louis97

Established Member
Joined
14 May 2008
Messages
2,150
Location
Derby
@MarkyT

Just for clarification. I'm specifically referring to the ones out London End of Platforms 8/9 at London Bridge which are placed about 10m before the Red. As London Bridge is a new installation I' wondering if this is a new standard for trainstop (TPWS) placement. It's a much better placement and should prevent a SPAD.

*edit*

HL17 briefing mentions TPWS grids provided more than 4m on the approach to the following signals to comply with signalling standards.

The TSS loops for TL2218 and TL2020, the signals at the London end of Platforms 8 and 9 respectively, were subject to re-positioning during the design phase as a result of a reduced overlap risk assessment. This was to mitigate against the consequence of a signal overrun. Both were moved to 9 metres in rear of the signal.
 

AndrewE

Established Member
Joined
9 Nov 2015
Messages
7,345
No, they display yellow or green aspects (or are blank when co-located with a stop signal displaying a danger aspect).
All right. Would you accept this? When first introduced they were mechanical and black and white, and showed clear (diagonal) or caution (horizontal) to avoid the conflict of it not being an actual signal, yet needing to show that a red might be coming up. The principle is still that you can't have a simple red signal that is not a mandatory stop!
 

ComUtoR

Established Member
Joined
13 Dec 2013
Messages
9,562
Location
UK
The TSS loops for TL2218 and TL2020,

As well as numerous other signals in the re-signalling.

the signals at the London end of Platforms 8 and 9 respectively, were subject to re-positioning during the design phase as a result of a reduced overlap risk assessment. This was to mitigate against the consequence of a signal overrun. Both were moved to 9 metres in rear of the signal.

My guess was around 10m :) My thoughts are really that not only will they mitigate against the consequences but prevent too.

Where it mentions that this is to 'comply with standards' Is this specifically because of the overlap distances and/or will new signals also have the grids placed similarly ? I feel that the new placement is an improvement over placement at the signal. Placing them like this will not only mitigate against overrun distances (bringing the overall severity ratings down) but potentially also reduce SPADS overall. (reduction of SASSPADS)

Thanks Louis97
 

ComUtoR

Established Member
Joined
13 Dec 2013
Messages
9,562
Location
UK
That's my understanding too. I can't think that it's anything to do with the signalman's actions - you couldn't pull the route and reset it quickly enough to avoid it visibly returning to danger (and I've seen it happen on auto signals too).

'Points bounce' :'(
 

SPADTrap

Established Member
Joined
15 Oct 2012
Messages
2,355
Has anyone else ever noticed a coloured light signal 'winking' once as though the signaller might have re-set the signal but to the same aspect it was already showing? LED type. Like the colour disappears for about .2 of a second but is then seen again? Or could this be a faulty signal? Note not seen this when a train has been anything within 3 mins of a signal.
I think it's an hourly self test. At least that is what I was told. Most annoying.
 

ComUtoR

Established Member
Joined
13 Dec 2013
Messages
9,562
Location
UK
I think it's an hourly self test. At least that is what I was told. Most annoying.

We have a service that always hits the point in which the banner blinks. It happens so regularly that when I drop into the gradient and sight the banner I find it more unusual for it not to blink. It's funny when a route learner/Trainee sees it blink for the first time. The look on their faces is priceless.

As I mentioned upthread. When signals do stuff like this it becomes so routine that if it was a fault then I doubt I would notice till it was too late.
 

MarkyT

Established Member
Joined
20 May 2012
Messages
7,573
Location
Torbay
I think it's an hourly self test. At least that is what I was told. Most annoying.

When TFMs (trackside functional modules - SSI's distributed input/output units) were first introduced in the 1980s, incandescent filament lamps were universal and the self test blink was hardly noticeable as the filament continued to glow for a short while after power was withdrawn. The now near universal LEDs go dark instantly when power is cut off so the blink has become more noticeable. Alternative modern object controllers should take this into account but there are very many older TFMs out there.
 

SPADTrap

Established Member
Joined
15 Oct 2012
Messages
2,355
When TFMs (trackside functional modules - SSI's distributed input/output units) were first introduced in the 1980s, incandescent filament lamps were universal and the self test blink was hardly noticeable as the filament continued to glow for a short while after power was withdrawn. The now near universal LEDs go dark instantly when power is cut off so the blink has become more noticeable. Alternative modern object controllers should take this into account but there are very many older TFMs out there.
Thank you for the benefit of your knowledge once again, MarkyT! :)
 

SPADTrap

Established Member
Joined
15 Oct 2012
Messages
2,355
We have a service that always hits the point in which the banner blinks. It happens so regularly that when I drop into the gradient and sight the banner I find it more unusual for it not to blink. It's funny when a route learner/Trainee sees it blink for the first time. The look on their faces is priceless.

As I mentioned upthread. When signals do stuff like this it becomes so routine that if it was a fault then I doubt I would notice till it was too late.

I'll admit to passing WH32BR multiple times a few weeks ago which was blank, and each time I couldn't convince myself what I had seen was correct! Very weird.
 

ComUtoR

Established Member
Joined
13 Dec 2013
Messages
9,562
Location
UK
Is that one of those ones that is blank unless on ?

Cheers Marky Mark and the Funky Technical info. Your technical knowledge never ceases to amaze.
 

driver_m

Established Member
Joined
8 Nov 2011
Messages
2,248
Regarding this blinking. It's well established amongst us on the WCML to expect it at certain locations, what I will say is that it was definitely noticeable on filaments as well as now with Dorman LEDs . Particularly with Stoke, Rugby SCC and Wembley Mainline boxes.
 
Joined
20 May 2009
Messages
330
Location
Bromley
It's not necessarily blinking, but I've seen slow flashing yellows on the signal at Chelsfield station before. It's a four-aspect that is just at the end of the London-bound platform. Was never sure of its significance.
 

bionic

Member
Joined
8 Nov 2013
Messages
883
It's not necessarily blinking, but I've seen slow flashing yellows on the signal at Chelsfield station before. It's a four-aspect that is just at the end of the London-bound platform. Was never sure of its significance.
You'll only get flashing yellows at Chelsfield if the route is set into platform 4 (up slow) at Orpington. A green means the route is set onto the up fast to platform 2. Two steady yellows tells you the signal before Orpington is at danger.
 
Status
Not open for further replies.

Top