What is the purpose of a fixed distant?

[BanburyBlue]

Hi all.

Can someone enlighten me as to what the purpose of a fixed distant? A fixed distant implies to me that the following home signal is always set at stop as the train is approaching. The only reason I can see for this is possibly when approaching a terminus.

So I’m guessing I must be missing something?

Apologies if a noddy question.

 

[pdeaves]

Approaching a terminus is one application, yes. Bourne End has a fixed distant (albeit at least one is a colour light fixed distant) on both approach lines.

 

[edwin_m]

When speeds are low enough that drivers can stop safely if they see the stop signal at danger then a worked distant doesn't serve much purpose, but the rules require every stop signal to be preceded by a distant (except when starting from a buffer stop). I think fixed distants may sometimes also have been used on the approach to a buffer stop.

 

[Nottingham59]

I'm no expert, but in addition to ends of line at termini, they can be used whenever all trains have to stop for some reason. For instance, I think they're used on the West Highland Line before passing loops where trains have to stop at Token Exchange Points.

 

[Gloster]

It also provides a reminder to the driver that he or she is at the braking distance for a Stop signal, which may be at stop, and they must start slowing down. In some areas it may not be so easy to identify the exact point at which to start braking, however good their route-knowledge is.

 

[dk1]

You can’t just have a red/stop signal without warning/braking distance.

 

[BanburyBlue]

There’s one as you are approaching London Marylebone on the High Wycombe line. If I remember, it’s just past Wembley around Neasden, a branch towards a cross London freight only line.

 

[a good off]

It’s effectively the semaphore version of a single yellow colour light aspect

 

[HSTEd]

Is this conceptually a similar idea to approach control? Albeit without setting a red on the home signal

 

[172007]

Worcester has several fixed distance signals. Simply a fixed signal requires no cable so, therefore, a saving in maintenence. TJ5 at Tunnel jct routes through to SH2 (SH2 being the first home for Shrub Hill signal box and platform 2 at its namesake station). The only trains to run through Shrub Hill are diverted XC (except 1 booked at day) or, the occasional freight bypassing the yard so why bother with a "movable" distant. TJ7 signal at Tunnel jct routes through to Foregate St, 2 out of 3 trains an hour turn back at Foregate St and the line speeds and sighting of signals upto Henwick section signal would not provide any advantage to a non fixed fixed distant sign

 

[a good off]

Is this conceptually a similar idea to approach control? Albeit without setting a red on the home signal

If a driver received a yellow aspect (or a a fixed distant) then they should start slowing down and be prepared for the next signal to be red. Fixed distant signals are also used in areas of low line speed such as Worcester and Shrewsbury which go in hand with the reduction of speed for the PSR.

 

[172007]

If a driver received a yellow aspect (or a a fixed distant) then they should start slowing down and be prepared for the next signal to be red. Fixed distant signals are also used in areas of low line speed such as Worcester and Shrewsbury which go in hand with the reduction of speed for the PSR.

Agree with this.

ultimately fixed distant ultimately saves money. No linkages, no wires, no levers, no interlocking, no cost except the actual fixed arm which requires a clean, lick of paint and probably replacement once in a blue moon.

 

[Annetts key]

Fixed distant signals, regardless of type are provided at service braking distance from either buffer stops, stop boards or signals that will be red/danger when the train approaches them. Or when the speed of the train will be low enough that having a worked distant (or colour light capable of showing a yellow/green aspect) gives no advantage. For example, on slow speed lines or where there are junction or other permanent speed restrictions.

One example of when a signal will always be red, is a signal that stays red until a token has been released for the single line section ahead. Or where interlocking controls require a track circuit to be occupied before the signal can be cleared.

 

[Gloster]

ultimately fixed distant ultimately saves money. No linkages, no wires, no levers, no interlocking, no cost except the actual fixed arm which requires a clean, lick of paint and probably replacement once in a blue moon.

Unless it is considered that the line will never be used in darkness or very poor visibility, the signal must have some sort of light. In this case it would be a single yellow at all times.

 

[splashoutradio]

Unless it is considered that the line will never be used in darkness or very poor visibility, the signal must have some sort of light. In this case it would be a single yellow at all times.

Not necessarily. Reflective distant boards are often used as fixed distants. An example of this is available here: https://www.rmweb.co.uk/community/uploads/monthly_07_2012/post-6662-0-08533200-1342781773.jpg

 

[Gloster]

Not necessarily. Reflective distant boards are often used as fixed distants. An example of this is available here: https://www.rmweb.co.uk/community/uploads/monthly_07_2012/post-6662-0-08533200-1342781773.jpg

Indeed, but just a plain signal is not suitable. Is that board the wrong way round or do the current standards allow it to have the notch on the rail side?

 

[splashoutradio]

You're very right. Did think it was upside down, but or sure how compliment it is. Doesn't look like it's on a preserved line, either.

 

[172007]

Attached is the December 2020 rulebook module RS521 page on Distant signals.

I believe there is one on the approach to Redditch according to a number of colleagues.

The RMweb photo above does have the sign the wrong way around.

 

[driver9000]

When speeds are low enough that drivers can stop safely if they see the stop signal at danger then a worked distant doesn't serve much purpose, but the rules require every stop signal to be preceded by a distant (except when starting from a buffer stop). I think fixed distants may sometimes also have been used on the approach to a buffer stop.

Every branch line terminal station I worked into had a Fixed Distant on its approach.

 

[ComUtoR]

They are also provided for SIMBIDS

 

[edwin_m]

Every branch line terminal station I worked into had a Fixed Distant on its approach.

I think there's a distinction that needs to be made here between a traditional fixed distant, that looks like a signal but doesn't move, and the more recent distant board, that has a picture of a distant arm on a reflective sign. I believe the boards have appeared in many places, like the approach to the termini, where earlier practice would have relied on driver route knowledge and not provided a fixed distant signal.

 

[55018ballymoss]

What everyone seems to have missed is the use of a fixed distant for the associated home signal which is approach controlled, and requires the train to slow for any route at the home signal (and is not on the approach to a terminal platform).
For my example I would suggest you look at Hellifield, where the line from Blackburn ends with a very slow curve into Hellifield station (15mph if I remember rightly from when I worked there), and the home signal can only be cleared once the track circuit on approach to the home signal has been occupied. This applies for the route into the down loop, or down main, so the distant is a fixed distant as the home signal will never be cleared before the train has passed the distant.

 

[scotraildriver]

In our RETB areas the fixed distant boards are unlit, however most of them have a blue TPWS light associated with the stop board at the token exchange point. A flashing light at the fixed distant indicates no need to stop at the TEP as the driver has a long section token.

 

[Annetts key]

What everyone seems to have missed is the use of a fixed distant for the associated home signal which is approach controlled, and requires the train to slow for any route at the home signal (and is not on the approach to a terminal platform).
For my example I would suggest you look at Hellifield, where the line from Blackburn ends with a very slow curve into Hellifield station (15mph if I remember rightly from when I worked there), and the home signal can only be cleared once the track circuit on approach to the home signal has been occupied. This applies for the route into the down loop, or down main, so the distant is a fixed distant as the home signal will never be cleared before the train has passed the distant.

That’s another example of what I was trying to include as a more general statement in post #13 above.

 

[edwin_m]

What everyone seems to have missed is the use of a fixed distant for the associated home signal which is approach controlled, and requires the train to slow for any route at the home signal (and is not on the approach to a terminal platform).
For my example I would suggest you look at Hellifield, where the line from Blackburn ends with a very slow curve into Hellifield station (15mph if I remember rightly from when I worked there), and the home signal can only be cleared once the track circuit on approach to the home signal has been occupied. This applies for the route into the down loop, or down main, so the distant is a fixed distant as the home signal will never be cleared before the train has passed the distant.

That's a fairly unusual situation. Normally when a restriction applies to all passing trains it is managed as a permanent speed restriction with signs and TPWS, and the signal can be cleared as soon as the state of the line ahead permits. In this situation a fixed distant might still be used if the restriction was low enough that the driver could stop on sight of the stop signal at danger.

The more usual application of approach control (either under the manual control of the signaller or automatically released from red in MAS areas) is at a diverging junction where one or more routes is significantly slower than the main route. In that case the distant or other signal providing the caution aspect would show that aspect, but it wouldn't be a fixed distant because it could still show green for the unrestricted route.

 

[Tomnick]

I think there's a distinction that needs to be made here between a traditional fixed distant, that looks like a signal but doesn't move, and the more recent distant board, that has a picture of a distant arm on a reflective sign. I believe the boards have appeared in many places, like the approach to the termini, where earlier practice would have relied on driver route knowledge and not provided a fixed distant signal.

I don’t know how widespread the practice of relying on drivers’ route knowledge rather than providing a fixed distant was, and when it ceased, but I’d suggest that most fixed distants reading onto buffer stops at a terminus probably date from the rationalisation of the layout at that terminus and abolition of whatever signalling was there previously.

What everyone seems to have missed is the use of a fixed distant for the associated home signal which is approach controlled, and requires the train to slow for any route at the home signal (and is not on the approach to a terminal platform).
For my example I would suggest you look at Hellifield, where the line from Blackburn ends with a very slow curve into Hellifield station (15mph if I remember rightly from when I worked there), and the home signal can only be cleared once the track circuit on approach to the home signal has been occupied. This applies for the route into the down loop, or down main, so the distant is a fixed distant as the home signal will never be cleared before the train has passed the distant.

Hellifield’s very unusual in that case then - approach control isn’t routinely provided where all routes from a signal are low speed (the advance warning board - “Morpeth board” - and nowadays TPWS suffice alone), although the low speeds might mean that a worked distant couldn’t be justified.

 

[ComUtoR]

but I’d suggest that most fixed distants reading onto buffer stops at a terminus probably date from the rationalisation of the layout at that terminus and abolition of whatever signalling was there previously.

If you had a fixed distant onto the buffers. How would you control movements if the platform was occupied ?

 

[edwin_m]

If you had a fixed distant onto the buffers. How would you control movements if the platform was occupied ?

Modern practice would be to have a subsidiary signal or aspect which would clear when the platform was part occupied, and the main signal would only clear if the platform was empty. Historically I believe some stations cleared the main stop signal for any move into the platform and additionally the distant if it was empty, but I believe this practice ended many years ago.

 

[Annetts key]

If you had a fixed distant onto the buffers. How would you control movements if the platform was occupied ?

The fixed distant signals that I’m aware of that are used on approach to terminal station platforms with buffers are all on non-permissive lines. So this is not an issue.

Where you have permissive passenger lines, generally these are more complex areas and hence have proper signalling.

 

[ComUtoR]

Apologies if Im confused but a fixed distant will always allow a train to pass it. Therefore if a train is occupying the section then how would it be protected ? If that section was a terminal platform with a buffer stop. It doesn't matter if its permissive or not. A train aproaching the distant will have a clear aspect.

1) [fixed distant] (train) [buffers] doesn't appear to have any protection arrangements.

2) [fixed distant] [stop] (train) [buffers] makes more sense.

Shouldn't a fixed distant always be preceeded by another signal rather than a set of buffers ?