Question re direction feathers at junction.

[Colin_McLeod]

I understand that at a junction a green (or yellow)  aspect with the feathers extinguished means proceeding along the main line.  If the diverging route is set then the feathers will be illuminated. 

 

I have a junction where the main line (continuous run) is the curved side of a right hand turnout and the diverging route (to the branch line) is actually "straight on".

 

In this situation would the feathers be angled to the left (for the branch even though it is geometrically 'straight on') or would they be angled to the right (for the main line)

 

In other words are feathers determined by the geometry of the turnout or are they determined by which route is the diverging route?

 

 

[Ian Smeeton]

Main aspect for the Main line, feathers for the 'branch' whatever the geometry.

 

Regards

 

Ian

[Mike_Walker]

Correct.  In your case it would have a Position 1 junction indicator, that is to the left.  

 

Junction indicator positions are designated 1 to 3, top to bottom, to the left and 4 to 6, again top to bottom on the right.

[Colin_McLeod]

Ian and Mike, thank you for your help.  Feathers to the left (position one) it is then.

 

Cheers

Colin

[The Johnster]

Aspect only, no feathers, main line.  Feathers may be set at 45, 90. or 135 degrees either side of the main aspect, so up to six on a single signal post though I doubt if that actually exists anywhere.  If all three are present they read top to bottom = 3rd,  2nd, and 1st junction in the indicated direction, the lit feathers indicating the set route.  If there are more than 6 directions or the speed limit for the main roud is less than 40mph, a route indicator board is used instead, and drivers' route knowledge includes the speed restrictions through each of the junctions and of course the main line.

[Nearholmer]

And, once in a blue moon it all goes badly wrong https://www.gov.uk/raib-reports/derailment-at-bletchley-junction-bletchley

[w124bob]

I can think of at least one instance where a route indicators are fitted for two routes, left or right but a plain aspect cannot be shown, coming off the Atherton line into Salford Cresent(this may have changed). I assume this was because both routes were of equal importance and speed. 

Another  signal situation I came across is  where trains reversed. In one instance a route indicator was lite despite it being the only route available, in an identical setting a plain signal. The difference here was that in the first example a train could approach the signal whilst moving, in the second it was a through station platform but with certain local trains terminating and reversing. In both cases trains moved through a facing crossover to gain the correct route.

What has been quoted above regarding the importance of  the mainline versus the branch is correct, but there could be exceptions.This is mainly down to the historical context of the route and when it was resignalled, early signalling schemes often simply replaced semaphores with colour lights like for like.

Edited January 9, 2022 by w124bob

[andyman7]

54 minutes ago, Nearholmer said:

And, once in a blue moon it all goes badly wrong https://www.gov.uk/raib-reports/derailment-at-bletchley-junction-bletchley

That was a Theatre indicator but emphasises why drivers need to know a route and pay attention. Railway signals are not like traffic lights - they are not designed to be interpreted simply on sight but in conjunction with route training as to what the various indications mean at each specific location ('F' in this case) 

 

3 minutes ago, w124bob said:

I can think of at least one instance where a route indicators are fitted for two routes, left or right but a plain aspect cannot be shown, coming off the Atherton line into Salford Cresent(this may have changed). I assume this was because both routes were of equal importance and speed. 

Another  signal situation I came across is  where trains reversed. In one instance a route indicator was lite despite it being the only route available, in an identical setting a plain signal. The difference here was that in the first example a train could approach the signal whilst moving, in the second it was a through station platform but with certain local trains terminating and reversing. In both cases trains moved through a facing crossover to gain the correct route.

Again, although there are standing principles (so, as per this thread, feather(s) for branches, no feather for main line) there are any number of locations specific signalling solutions, each of which will be covered in the relevant local instructions and the route training for route(s) through them.

[BR traction instructor]

It used to be interesting at Clay Cross. Running at speed under clear signals on the up main with e.g. a fully fitted freight, parcels or passenger in the 1990s and approaching the junction southbound, there was insufficient distance to bring the train safely to a stand at the junction signal if the junction had been set for the wrong direction/signal cleared, due to the restricted view of the junction signal. ISTR that flashing yellows were subsequently fitted to give warning of the route setting. It wasn’t a dangerous situation, due to similar line speed in either direction but the implication for a driver was that taking an incorrect route at a junction was classed as passing a signal at danger.

 

BeRTIe

Edited January 9, 2022 by BR traction instructor

[St. Simon]

 

12 hours ago, Ian Smeeton said:

Main aspect for the Main line, feathers for the 'branch' whatever the geometry.

 

12 hours ago, Mike_Walker said:

Correct.  In your case it would have a Position 1 junction indicator, that is to the left.  

 

Junction indicator positions are designated 1 to 3, top to bottom, to the left and 4 to 6, again top to bottom on the right.

 

8 hours ago, The Johnster said:

Aspect only, no feathers, main line.  

Hi,

 

Nope, Feathers are allocated on Geometry not whether the line is Main or Branch*, it’s just in most cases the Main is the straight on route.

 

The Junction Indicator (the actual term for a Feather) is precisely that, it indicates the route the train is taking at the junction so that the driver can manage their speed accordingly, so therefore it is better for the JI to be related to the geometry at the points rather than the importance of the line, so it is easier for the drivers to remember it. 

My book explains it all

 

*It might have been the historically that the type of line determined the JI, but not now and hasn’t been for many many years.

 

Simon

Edited January 9, 2022 by St. Simon

[cb900f]

7 minutes ago, BR traction instructor said:

It used to be interesting at Clay Cross. Running at speed under clear signals with e.g. a fully fitted freight, parcels or passenger in the 1990s and approaching the junction southbound, there was insufficient distance to bring the train safely to a stand at the junction signal if the junction had been set for the wrong direction/signal cleared, due to the restricted view of the junction signal. ISTR that flashing yellows were subsequently fitted to give warning of the route setting. It wasn’t a dangerous situation, due to similar line speed in either direction but the implication for a driver was that taking an incorrect route at a junction was classed as passing a signal at danger.

 

BeRTIe

Clay Cross never had flashing yellows although I agree it was a perfect example of a situation that should have. If you remember they relocated the signal to the north side of the station bridge thereby giving the Dvr an earlier view of the aspect displayed.

[St. Simon]

Hi Colin,

 

I would have a Position 4 Junction Indicator on the Junction Signal not a Position 1.

 

Simon

[St. Simon]

7 minutes ago, cb900f said:

Clay Cross never had flashing yellows although I agree it was a perfect example of a situation that should have. If you remember they relocated the signal to the north side of the station bridge thereby giving the Dvr an earlier view of the aspect displayed.

Hi,

 

But as a concept Flashing Yellows don’t give an indication of which route you are taking, only that you are diverging from the straight on route, so in a case where you have multiple divergent routes that are suitable for Flashing Yellows, you really have to have a different way of indicating the route before reaching the junction signal, such as a Splitting Distant or Preliminary Route Indicators (but these might not have been in use then)

 

If the junction at Clay Cross only has two routes or if only one route is suitable for Flashing Yellows, (sorry not familiar with the area), then yes Flashing Yellows would be fine.

 

Simon

Edited January 9, 2022 by St. Simon

[BR traction instructor]

9 minutes ago, cb900f said:

Clay Cross never had flashing yellows although I agree it was a perfect example of a situation that should have. If you remember they relocated the signal to the north side of the station bridge thereby giving the Dvr an earlier view of the aspect displayed.

I moved on to become a full time classroom instructor in 1992 hence being unsure of what came after from a signal mod point of view.

 

BeRTIe

Edited January 9, 2022 by BR traction instructor

[big jim]

South Ruislip used to be back to front, feathers (No1 route indicator) to take the chiltern mainline to marylebone and main aspect only to head toward Greenford down the branch line, this of course being a throwback to when the mainline went to Paddington and the branch was the line toward Marylebone, it’s been remodelled now with a totally new down line added and the line to Greenford being accessed via a crossover at the north end of the station and running bidirectional via the down line 

 

you can very beiefy see the signal at 1:19

 

[russ p]

31 minutes ago, BR traction instructor said:

It used to be interesting at Clay Cross. Running at speed under clear signals on the up main with e.g. a fully fitted freight, parcels or passenger in the 1990s and approaching the junction southbound, there was insufficient distance to bring the train safely to a stand at the junction signal if the junction had been set for the wrong direction/signal cleared, due to the restricted view of the junction signal. ISTR that flashing yellows were subsequently fitted to give warning of the route setting. It wasn’t a dangerous situation, due to similar line speed in either direction but the implication for a driver was that taking an incorrect route at a junction was classed as passing a signal at danger.

 

BeRTIe

 

Colton junction is still the same 125mph both directions and you get a feather for both routes and you can't find get a decent view of them until you are on top of them. I've Ben wrong routed there a couple of times in the past. Didn't matter then as you could go via Doncaster.  It actually did me a favour as Tees -Tinsley and return was mileage via Doncaster! 

[BR traction instructor]

I was never wrong routed at Clay Cross but approaching at around 90mph with a 47 and four bogie vans (Piccadilly to Pancras parcels, limited brake force) you knew that you were going whichever way the points were set.

 

BeRTIe

Edited January 9, 2022 by BR traction instructor

[Nearholmer]

1 hour ago, andyman7 said:

Railway signals are not like traffic lights - they are not designed to be interpreted simply on sight but in conjunction with route training as to what the various indications mean at each specific location ('F' in this case) 

That I understand.

 

That I also think is a design weakness which, these days, wouldn’t be tolerated in any other safety-critical application that relies on the operator interpreting visual indications. It’s an approach that invites trouble, by asking a lot of the human cognitive system.

 

I know that modern signalling design does go a lot further in attempting to make what is shown intuitive, and to avoid over-reliance on the driver’s memory.

[andyman7]

2 minutes ago, Nearholmer said:

That I understand.

 

That I also think is a design weakness which, these days, wouldn’t be tolerated in any other safety-critical application that relies on the operator interpreting visual indications. It’s an approach that invites trouble, by asking a lot of the human cognitive system.

 

I know that modern signalling design does go a lot further in attempting to make what is shown intuitive, and to avoid over-reliance on the driver’s memory.

I think that's the way things are heading, especially with ERTMS and in cab signalling. Of course it's politically fraught, because any endeavour that seeks to reduce reliance on specialist and lengthy training is also reducing the barriers to that role, which the unions do not want. And of course they will play the safety card even if it can be proven that reducing reliance on human action as the single point of criticality makes things safer. 

[BR traction instructor]

In response to Nearholmer’s post above. Railway operations long pre date most, or all road traffic lights and have been developed over a considerable period of time. The training given to me as a trainee driver in 1987 under BR was exhaustive and covered a great deal of variety emerging from numerous historic railway companies/regions. Route learning then allowed individual  features of various routes to be studied and absorbed.

 

BeRTIe

Edited January 9, 2022 by BR traction instructor

[Oldddudders]

2 hours ago, Nearholmer said:

And, once in a blue moon it all goes badly wrong https://www.gov.uk/raib-reports/derailment-at-bletchley-junction-bletchley

While clearly the driver failed to spot the correctly-illuminated route indicator, he may also have shown a failure to understand approach control. With such a dramatic difference between linespeed and the diverging route, the proceed aspect is not displayed until a preset time has elapsed since the berth track circuit was first occupied. That timer circuit, which is regularly checked by the techs, is designed to ensure the loco or train has reduced speed sufficiently, and is therefore customised to the location.

 

As has been pointed out, when a driver signs a route, he declares he understands all its physical features, and that would include understanding the characteristics of each signal he sees. Being brought to a virtual stand at this signal ought to have made him consider that a diverging route had been set.

[Michael Hodgson]

10 hours ago, The Johnster said:

Aspect only, no feathers, main line.  Feathers may be set at 45, 90. or 135 degrees either side of the main aspect, so up to six on a single signal post though I doubt if that actually exists anywhere.  

I understand that combinations of position 1 and 6 or 4 and 5 are deprecated because diagonally opposed feathers are open to misinterpretation, although quite a number of instances can be found.

There's an example at Nuneaton with 5 feathers and I understand that's the most there is.

 

Also four feather with positions 2 & 5, which I think can be found approaching Gloucester on the line from Chepstow .

Edited January 9, 2022 by Michael Hodgson
postscript

[Rugd1022]

10 hours ago, The Johnster said:

Aspect only, no feathers, main line.  Feathers may be set at 45, 90. or 135 degrees either side of the main aspect, so up to six on a single signal post though I doubt if that actually exists anywhere.  If all three are present they read top to bottom = 3rd,  2nd, and 1st junction in the indicated direction, the lit feathers indicating the set route.  If there are more than 6 directions or the speed limit for the main roud is less than 40mph, a route indicator board is used instead, and drivers' route knowledge includes the speed restrictions through each of the junctions and of course the main line.

 

The closest I can find is this now long gone example at Nuneaton where you came off the line from Arley Tunnel, only five feathers but it's making me wonder if there is (or was) one somewhere with six on it....

 

 

To some train crew route indicators / feathers are also known as 'flashes', although it's not that commonly used.

[keefer]

1 hour ago, big jim said:

South Ruislip used to be back to front, feathers (No1 route indicator) to take the chiltern mainline to marylebone and main aspect only to head toward Greenford down the branch line, this of course being a throwback to when the mainline went to Paddington and the branch was the line toward Marylebone, it’s been remodelled now with a totally new down line added and the line to Greenford being accessed via a crossover at the north end of the station and running bidirectional via the down line 

 

This video from a Thumper railtour shows the line from West Ruislip to Greenford in 2017.

At the start, they are given main aspect only, which is for Marylebone, so they have to wait until they are given the no.4 JI to cross over onto the Down main to head for Greenford. It's mentioned that due to various speed/capacity improvements (presumably for the Chiltern main line), this is the only way to reach Greenford.

At Ruislip Gardens they get another no.4 JI onto the Up/Down Northolt Loop which diverges just south of South Ruislip, going onto the single line Greenford route (remains of the NNML)

https://youtu.be/KAEOaqvw0OM

Edited January 9, 2022 by keefer

[Colin_McLeod]

13 hours ago, Ian Smeeton said:

Main aspect for the Main line, feathers for the 'branch' whatever the geometry.

 

13 hours ago, Mike_Walker said:

Correct.  In your case it would have a Position 1 junction indicator, that is to the left.  

 

10 hours ago, The Johnster said:

Aspect only, no feathers, main line.  

 

 

Consistent advice.

 

 

1 hour ago, St. Simon said:

Nope, Feathers are allocated on Geometry not whether the line is Main or Branch*, it’s just in most cases the Main is the straight on route.

 

(snip)

 

*It might have been the historically that the type of line determined the JI, but not now and hasn’t been for many many years.

 

1 hour ago, St. Simon said:

I would have a Position 4 Junction Indicator on the Junction Signal not a Position 1.

 

 

 

Oh dear.  Back where I started.

 

 

Though perhaps St. Simon's last paragraph gives room to manoeuvre depending on whether my model is of a current system or one that was based on type of line.

 

Applying Rule one is unclear as I have stock from a range of eras.