In a run of automatic signals, why do we have a couple of non-automatics?

Sometimes it is because there used to be something there (such as a level crossing). If the crossing is removed, it is easier to leave the signals as is rather than convert to automatics.

Is there any design preference in the real world for this (signal with an auto button) versus emergency replacement buttons on signals that are full time auto's ?

Motherwell has several sets of 'E' on plain line between Carstairs and Gretna, about 1 signal in 5 depending on other nearby controlled items like LC and loops.

bill_gensheet in post 130213 said:

Is there any design preference in the real world for this (signal with an auto button) versus emergency replacement buttons on signals that are full time auto's ?

Motherwell has several sets of 'E' on plain line between Carstairs and Gretna, about 1 signal in 5 depending on other nearby controlled items like LC and loops.

The preference is emergency replacement. A controlled signal would only be provided in special situations or because they used to be there for some other reason.

1 in 5 used to be the standard; more precisely, you put in E buttons to replace AHBs or to protect tunnels and viaducts, then add others to ensure there are never more than 4 signals in a row without them.

The modern standard is to put E buttons on every signal. With SSIs and IECCs there's no additional wiring required and only a trivial amount of extra code, so why not?

I remember reading in a book series entitled 'signalman trilogy' that it was introduced as there was no way anyone could stop a train on auto sections. It was brought up with management, who thought it was a costly feature or something like that, and wasn't retro fitted until a derailment of a class 8 or 9 between Didcot and uffington due to a hotbox. This was around the time Didcot psb went live in the mid 60s.

03piggs in post 130214 said:

I remember reading in a book series entitled 'signalman trilogy' that it was introduced as there was no way anyone could stop a train on auto sections. It was brought up with management, who thought it was a costly feature or something like that, and wasn't retro fitted until a derailment of a class 8 or 9 between Didcot and uffington due to a hotbox. This was around the time Didcot psb went live in the mid 60s.

Adrian Vaughan, "Signalman's Nightmare".

I think they also had a train that went wrong-line for several miles, including over open level crossings, and no way to turn a green signal red to hopefully alert them.

clive in post 130219 said:

03piggs in post 130214 said:

I remember reading in a book series entitled 'signalman trilogy' that it was introduced as there was no way anyone could stop a train on auto sections. It was brought up with management, who thought it was a costly feature or something like that, and wasn't retro fitted until a derailment of a class 8 or 9 between Didcot and uffington due to a hotbox. This was around the time Didcot psb went live in the mid 60s.

Adrian Vaughan, "Signalman's Nightmare".

I think they also had a train that went wrong-line for several miles, including over open level crossings, and no way to turn a green signal red to hopefully alert them.

Yes! Thanks Clive, I couldn't remember the author.

Reminds me I really should re-read those books again....🤔🤔

Is there any design preference in the real world for this (signal with an auto button) versus emergency replacement buttons on signals that are full time auto's ?

03piggs in post 130220 said:

clive in post 130219 said:

03piggs in post 130214 said:

I remember reading in a book series entitled 'signalman trilogy' that it was introduced as there was no way anyone could stop a train on auto sections. It was brought up with management, who thought it was a costly feature or something like that, and wasn't retro fitted until a derailment of a class 8 or 9 between Didcot and uffington due to a hotbox. This was around the time Didcot psb went live in the mid 60s.

Adrian Vaughan, "Signalman's Nightmare".

I think they also had a train that went wrong-line for several miles, including over open level crossings, and no way to turn a green signal red to hopefully alert them.

Yes! Thanks Clive, I couldn't remember the author.

Reminds me I really should re-read those books again....🤔🤔

He got booted from a Facebook signalling group because, though he might be a good author, it turns out he had zero respect for anybody's opinion or for modern signalling. Mods got tired of his frequent rants and personal attacks. Good riddance.

807 / 811 have "Class 9" controls fitted, so I presume they are controlled signals for that reason.

896 looks to be to stop trains towards Westbury PSB if the emergency alarm is sent to Reading PSB.

headshot119 in post 130211 said:

807 / 811 have "Class 9" controls fitted, so I presume they are controlled signals for that reason.

896 looks to be to stop trains towards Westbury PSB if the emergency alarm is sent to Reading PSB.

My drivers' route map of the Reading to Westbury section annotates TR896 signal on the Down Westbury as being the "Last TVSC Signal". I remember being told years ago (and I don't know if this is still, or ever was, a thing) that the last signal in each signalbox's area was a controlled signal.

The obvious reason, as you suggest, is so that the signaller in rear can stop a train before it enters the next signaller's area. I don't know of any other technical reason why it would be a controlled signal.

In the up direction, Westbury's last signal is automatic signal UW93, followed by autos UW91 and UW90. Then it's the mysterious controlled TR807, located about half a mile physically from TR896 on the Down Westbury.

TR896 and TR807 are either side of the site of the old Lavington station. I can find no evidence of a level crossing ever existing at Lavintgon (mostly from old photos), but photos show that the goods yard on the down side required crossovers to be protected by signals. If any of the pointwork still existed when the line was converted to colour light signals back in the day then the new signals there would have been controlled ones. I'm not entirely sure when the B&H was re-signalled to colour light - does anyone have any info on this, or a website or something? I can't find anything.

As for TR811, I can see no obvious reason why that would be controlled, other than because there used to be emergency crossovers at Urchfont. But then that would imply that automatic DW83 in the other direction should also be a controlled signal. The topography of the line at Urchfont (an embankment on a hill in the middle of nowhere) suggests there was clearly never a road crossing there.

R896 and R807 (Now renumbered TRxxx) protected Lavington Emergency GF, that was removed in early 2000s

R811 (as well as R807) protected a set of spring catch points in the Up Westbury to protect against trains running away on the uphill Grade to Woodborough - there were box instructions for working unfitted or partially fitted trains over the B&H where those signals had to be maintained at Danger behind such trains until said trains had passed a given point further up line.

JamesN in post 130260 said:

R896 and R807 (Now renumbered TRxxx) protected Lavington Emergency GF, that was removed in early 2000s

R811 (as well as R807) protected a set of spring catch points in the Up Westbury to protect against trains running away on the uphill Grade to Woodborough - there were box instructions for working unfitted or partially fitted trains over the B&H where those signals had to be maintained at Danger behind such trains until said trains had passed a given point further up line.

Well I think you've just answered the OP's question, as well as more or less confirming my suspicions about left-over pointwork at Lavington.

Do you have any more info about old track layouts and signalling on the B&H? It's a line I drive regularly and it's always nice to know more about how it used to be back in the day.

(Fun fact - my avatar is a photo of me driving 57303 with ECS sleeper stock, on the Up Westbury near Frome back in 2015.)

[...]

R896 and R807 (Now renumbered TRxxx) protected Lavington Emergency GF, that was removed in early 2000s

R811 (as well as R807) protected a set of spring catch points in the Up Westbury to protect against trains running away on the uphill Grade to Woodborough - there were box instructions for working unfitted or partially fitted trains over the B&H where those signals had to be maintained at Danger behind such trains until said trains had passed a given point further up line.

JamesN in post 130260 said:

[...]

R896 and R807 (Now renumbered TRxxx) protected Lavington Emergency GF, that was removed in early 2000s

R811 (as well as R807) protected a set of spring catch points in the Up Westbury to protect against trains running away on the uphill Grade to Woodborough - there were box instructions for working unfitted or partially fitted trains over the B&H where those signals had to be maintained at Danger behind such trains until said trains had passed a given point further up line.

The Westbury signal number plan still shows the emergency GF - which is no longer there on the sim's present version. (The signal numbers on that plan don't match those on the present sim either. Not only the Reading panel differs but also UW93 is UW92 there.)

OpenStreetMap shows me a foot crossing at Urchfont, but it is probably not the reason why there is a signal. The reason is also not the Devizes branch closed 1966 - measuring distances on Google Maps and comparing them with the length of track circuits in the sim, it appears that that junction would have been between present-day UW83 and UW82. EDIT: I didn't read properly. JamesN already answered this.

I remember being told years ago (and I don't know if this is still, or ever was, a thing) that the last signal in each signalbox's area was a controlled signal.

Going to add here, not forgetting the difference in E and R replacements. R being guaranteed, E not being guaranteed (Or is it other way around).

Going slightly off topic, when would R replacements have started to become common?