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Hi,

 

This is one for the signalling engineers / designers.

 

On Norwood Road, I have a signal sighting problem with my headshunt, it's too short, just. The situation is this:

 

When I stable Class 67's and 68's in there (and probably 37's, but I haven't tried), the locos are hard up against the buffers and the wheels are behind the shunt signal and track joint, but the cab is in line with signal (see picture below), giving the driver no indication of when the signal is off.

 

post-7271-0-90985500-1514469888_thumb.jpg

 

Just to note that there are two shunts for the headshunt in the photo, but the tall on is the commissioned signal, with the short one being out of use

 

I can't extend the headshunt and I can't move the signal forward (as this would mean locos would be foul of the crossovers. The headshunt works for shorter locos, but I want to be able to stable large locos in there as well.

 

So, what would you do as a signalling solution?

 

I think an off indicator mounted ahead of the signal would do the trick, although in talking with my boss about it, he thinks it's overkill! Whilst I'm not too worried about it being absolutely prototypical, I would like a realistic solution.

 

Simon

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Hi,

This is one for the signalling engineers / designers.

On Norwood Road, I have a signal sighting problem with my headshunt, it's too short, just. The situation is this:

When I stable Class 67's and 68's in there (and probably 37's, but I haven't tried), the locos are hard up against the buffers and the wheels are behind the shunt signal and track joint, but the cab is in line with signal (see picture below), giving the driver no indication of when the signal is off.

attachicon.gifIMG_1754.JPG

Just to note that there are two shunts for the headshunt in the photo, but the tall on is the commissioned signal, with the short one being out of use

I can't extend the headshunt and I can't move the signal forward (as this would mean locos would be foul of the crossovers. The headshunt works for shorter locos, but I want to be able to stable large locos in there as well.

So, what would you do as a signalling solution?

I think an off indicator mounted ahead of the signal would do the trick, although in talking with my boss about it, he thinks it's overkill! Whilst I'm not too worried about it being absolutely prototypical, I would like a realistic solution.

Simon

Hi Simon,

 

You've ruled out the obvious options of either lengthening the siding or repositioning the signal. So it has to be some other signalling solution - perhaps mounting the sub signal on a tall post (like the ones at Doncaster) to give the driver better sighting? Failing that, implement "full in-cab signalling" and abolish lineside signals altogether? Only joking, that would render your layout somewhat dull and a bit uninteresting.

 

Regards, Ian.

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Hi Simon,

You've ruled out the obvious options of either lengthening the siding or repositioning the signal. So it has to be some other signalling solution - perhaps mounting the sub signal on a tall post (like the ones at Doncaster) to give the driver better sighting? Failing that, implement "full in-cab signalling" and abolish lineside signals altogether? Only joking, that would render your layout somewhat dull and a bit uninteresting.

Regards, Ian.

The signal has already been installed, and I'm not sure if I can fit one in the higher structure gauge. Plus I'm not sure if that would give the driver any more sighting of them due to the position of the cab relative to the signals, but I did think of that.

 

Cab signalling could be fun, you could have PoSA routes and it would make the interlocking interesting!

 

Simon

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The signal has already been installed, and I'm not sure if I can fit one in the higher structure gauge. Plus I'm not sure if that would give the driver any more sighting of them due to the position of the cab relative to the signals, but I did think of that.

 

Cab signalling could be fun, you could have PoSA routes and it would make the interlocking interesting!

 

Simon

Mmm ..... it would seem that all the obvious solutions have been ruled out (in my limited signalling knowledge). If this scenario were to occur in "real-life" and no (reasonable/affordable) signalling option were available, then I guess the fall-back would be an "operational instruction" banning certain traction from using the siding unless a "second person" was available to confirm to the driver that the signal was "off".

 

By the way, is this a trick question - are you just testing us? Do you already know the answer?

 

Regards, Ian.

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Mmm ..... it would seem that all the obvious solutions have been ruled out (in my limited signalling knowledge). If this scenario were to occur in "real-life" and no (reasonable/affordable) signalling option were available, then I guess the fall-back would be an "operational instruction" banning certain traction from using the siding unless a "second person" was available to confirm to the driver that the signal was "off".

 

By the way, is this a trick question - are you just testing us? Do you already know the answer?

 

Regards, Ian.

Yes, there might be an operational instruction.

 

No, not a trick question at all, I have a solution (to put an OFF indicator on the back of a signal), but I was genuinely wandering what would other signalling engineers would do in this circumstance.

 

Simon

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Simon

As a former S&T bod the answer is that the signal engineer would do absolutely nothing other than say your siding is too short. In the real world any vehicle that coudn't be parked with adequate sighting of the signal would be banned from using it. Unfortunately there is no realistic getout, don't seem to be any traps either.

 

Regards

Martin

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If there is a trap or derailer putting anything which fits within the length from the stop block to the TC joint at the points isn't necessarily a problem. In some places there were signals which had an OFF indicator on the back, fitted with an amber filter IIRC to distinguish it from other indicators, where sighting was a problem. Elsewhere there was a local instruction and nowadays there may possibly even be a board telling the Driver to check the signal is OFF before proceeding. 

 

In platforms or on running lines without trap protection it becomes more difficult. At Wolverhampton post-electrification there used to be a problem with the North Bay before it was rebuilt on the Banana Yard alignment. the signal was perfectly OK with a 2-car unit or a 3-car 57' set but the Shrewsbury and Chester trains often threw up a Class 116 or 120. With these the outermost wheels were inside the TC Clearance joint but the cab was level with the signal so couldn't be seen from the chair. Additionally it was on the opposite side from the platform so couldn't be seen by the Guard due to the alignment. I remember some drivers would go to the first window behind the cab to check that the signal was clear when the Guard gave two on the buzzer. There was also a signal at New Street where it was necessary to pull right up with a long train on. It was OK with a 45 but from a 47 the signal was not visible. The problem there was that there was a crossover just ahead of the signal and a second signal at the platform end for a train coming across in front. The 'R' indication on that signal was inhibited with the points reverse. 

 

(Tongue in cheek mode) Otherwise, get a Driver to put the engine behind the signal then carry out repairs in such a way that it will fit in future.

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Simon

As a former S&T bod the answer is that the signal engineer would do absolutely nothing other than say your siding is too short. In the real world any vehicle that coudn't be parked with adequate sighting of the signal would be banned from using it. Unfortunately there is no realistic getout, don't seem to be any traps either.

 

Regards

Martin

There are similar real world cases at Nottingham, Lincoln and Alton although they have main aspects and co-actors, which is overkill for my headshunt.

 

Trap points aren't needed as the feeds into a turnback siding which isn't a passenger line, and I've got restoration reminders on the points.

 

Simon

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There are similar real world cases at Nottingham, Lincoln and Alton although they have main aspects and co-actors, which is overkill for my headshunt.

 

Trap points aren't needed as the feeds into a turnback siding which isn't a passenger line, and I've got restoration reminders on the points.

 

Simon

I was about to mention the Nottingham one, but for the benefit of others it is a main aspect rotated through 90 degrees to shine through the cab window, needed if a three-car unit is sitting in platform 2.  Must be horribly dazzling if the driver looks straight at it, unless it's been dimmed somehow. 

 

There are a few places where the co-actor is beyond the main signal.  Not sure an off indicator would be allowed as I think a driver isn't allowed to take one as authority to move a train. 

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I was about to mention the Nottingham one, but for the benefit of others it is a main aspect rotated through 90 degrees to shine through the cab window, needed if a three-car unit is sitting in platform 2.  Must be horribly dazzling if the driver looks straight at it, unless it's been dimmed somehow.

 

There are a few places where the co-actor is beyond the main signal.  Not sure an off indicator would be allowed as I think a driver isn't allowed to take one as authority to move a train.

 

I don't think the main beam is directed at the driver, just above or below his line of sight to prevent dazzling

 

OFF Indicators can be used as a authority to move a train, there's a few places on the MML that have OFF Indicators for shunt signals for trains backing into yards. If they are on a platform, then I think they are only to be used by station staff.

 

Simon

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Simon

As a former S&T bod the answer is that the signal engineer would do absolutely nothing other than say your siding is too short. In the real world any vehicle that coudn't be parked with adequate sighting of the signal would be banned from using it. Unfortunately there is no realistic getout, don't seem to be any traps either.

 

Regards

Martin

 

Two answers and that would be one of them. The other - as already mentioned - would be an Instruction to Drivers/Shunters to check that the signal is showing a proceed aspect before commencing a movement past it although it should hardly be necessary to remind people of something which is in the Rule Book (although nowadays that seems to be done quite often).  

 

In reality in most cases I suspect that when the operators check the scheme plan prior to signing it off the question would be asked if the spur is long enough and the most likely response would be to restrict the classes of loco permitted to use it unless it can be extended.

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I am puzzled why the head-shunt can't be extended. From your photo there seems to be plenty of room beyond it for the amount of track needed. I am just curious - I expect that there is a very good reason.

Yes, you are right, but I just don't want to go ripping up scenic work to extend the headshunt, particularly as the layout is out at the beginning of February and I haven't tested the signalling yet!

 

Simon

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OFF Indicators can be used as a authority to move a train, there's a few places on the MML that have OFF Indicators for shunt signals for trains backing into yards. If they are on a platform, then I think they are only to be used by station staff.

 

Simon

There were several on Saltley PSB e.g. for setting back into Lawley Street. The signals were originally slotted by Lawley Street A Shunt Frame. After that closed IIRC  we provided Shunters Plungers at the signals to confirm that the road was correctly set inside the yard before the OFF indicator would illuminate.

 

 

Yes, you are right, but I just don't want to go ripping up scenic work to extend the headshunt, ....................................

Simon

Coachmann would have been to the shed, done it and gone back indoors in the length of time this thread has been running.

 

Eric

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Yes, you are right, but I just don't want to go ripping up scenic work to extend the headshunt, particularly as the layout is out at the beginning of February and I haven't tested the signalling yet!

 

Simon

 

I know diddly squat about signalling, but, it seems to me it's your only/best option, I deduce from your comments you are not happy with the situation.

 

Mike.

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I can tell you why the headshunt's too short... it was only meant for a Class 33! At a shade over 8" buffer to buffer, they're a wee bit smaller than the 68 in your picture.

 

post-17811-0-76256100-1514542370.jpg

 

In all seriousness, if you do want to extend the length... concrete sleepers are Exactoscale, wooden sleepers are Tillig, and the rail is Tillig Code 83 flatbottom. The ballast used was Woodland Scenics fine light grey with a liberal dose of Humbrol 29 to blend it all in. It shouldn't be a huge job.

 

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Admittedly I can't see all of the layout, but I am slightly surprised that the siding hasn't got a trap point, in which case an important clue to a driver that he is likely to get the route is sight of the trap points going over. As it is, about the only way the driver could see the signal would be to look out of the cab door, although on older locos there would have been a fair chance that he could have seen it by looking out of the cab side window.

In this day and age, when prescriptive standards rule, the only real solution is to extend the siding, when of course you will also have to accommodate the considerably increased stand back distance required to allow for train drivers' inability to look other than straight ahead. But, in your position, with a show coming up that soon, I would take the Nelsonian approach and leave it until later. Most of the audience won't even notice (although you will).

The E&P Engineer wouldn't be terribly impressed by the conductor rail layout through that turnout either. The ramp ends on the two legs of the turnout should be abreast of each other in order to provide sufficient lateral offset to avoid the shoes getting caught up in the rail.

 

Jim

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Coachmann would have been to the shed, done it and gone back indoors in the length of time this thread has been running.

 

Eric

 

 

Ah yes, but I don't have the skills of Mr Coachmann!

 

 

I deduce from your comments you are not happy with the situation.

 

Mike.

  

 

I'm not unhappy with the situation, the line is long enough, I don't see the point in extending the headshunt. It's basically because I like very odd signalling, because I like seeing the armchair experts squirm ;) , and I thought this might be a way of introducing another odd signalling arrangement on to the layout.

 

I can tell you why the headshunt's too short... it was only meant for a Class 33! At a shade over 8" buffer to buffer, they're a wee bit smaller than the 68 in your picture.

 

attachicon.gifwest_croydon_067.jpg

 

In all seriousness, if you do want to extend the length... concrete sleepers are Exactoscale, wooden sleepers are Tillig, and the rail is Tillig Code 83 flatbottom. The ballast used was Woodland Scenics fine light grey with a liberal dose of Humbrol 29 to blend it all in. It shouldn't be a huge job.

The headshunt is still the right length, it's just my placing of signals was a bit out, so it's my own doing! I like having operational restrictions like this as it makes it more interesting.

 

Simon

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Admittedly I can't see all of the layout, but I am slightly surprised that the siding hasn't got a trap point, in which case an important clue to a driver that he is likely to get the route is sight of the trap points going over. As it is, about the only way the driver could see the signal would be to look out of the cab door, although on older locos there would have been a fair chance that he could have seen it by looking out of the cab side window.

In this day and age, when prescriptive standards rule, the only real solution is to extend the siding, when of course you will also have to accommodate the considerably increased stand back distance required to allow for train drivers' inability to look other than straight ahead. But, in your position, with a show coming up that soon, I would take the Nelsonian approach and leave it until later. Most of the audience won't even notice (although you will).

The E&P Engineer wouldn't be terribly impressed by the conductor rail layout through that turnout either. The ramp ends on the two legs of the turnout should be abreast of each other in order to provide sufficient lateral offset to avoid the shoes getting caught up in the rail.

Jim

Hi Jim,

 

What the picture doesn't show is that the headshunt feeds straight into a none passenger turnback siding, so no trapping protection is required, same arrangement at Maidenhead and West Croydon. The trapping protection for the main lines either side is through the two crossovers set normal and I've provided restoration reminders for these on the panel.

 

Simon

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Hi Simon,

 

Could a temporary solution work in the short-term? You could remove the buffer stop and replace it with a red & white sleeper (as per the attached photos). That might create just a bit more room without hacking about the scenery or the signalling?

 

post-32776-0-77400600-1514543953_thumb.jpg

post-32776-0-72045400-1514544019_thumb.jpg

 

Just a thought.

 

Regards, Ian.

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Simon while there might be a signalling solution I think you'd find the drivers reps would black it due to SPAD risk not being able to properly see the signal. Also a loco shouldn't have to hit the buffers, it's counted as a collision.

I'm afraid the practical solution is put siding out of use except to shorter locos, 08 or possibly 33's?, or extend the headshunt by a small amount.

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Hi Jim,

 

What the picture doesn't show is that the headshunt feeds straight into a none passenger turnback siding, so no trapping protection is required, same arrangement at Maidenhead and West Croydon. The trapping protection for the main lines either side is through the two crossovers set normal and I've provided restoration reminders for these on the panel.

 

Simon

As I suspected it might, that's what happens when you can't see all of the picture. :read:

 

As for the conductor rail, have you got access to the NR standards? If yes, as I suspect, I 'll give you the necessary reference. :)

 

Jim

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Hi,

 

This is one for the signalling engineers / designers.

 

On Norwood Road, I have a signal sighting problem with my headshunt, it's too short, just. The situation is this:

 

When I stable Class 67's and 68's in there (and probably 37's, but I haven't tried), the locos are hard up against the buffers and the wheels are behind the shunt signal and track joint, but the cab is in line with signal (see picture below), giving the driver no indication of when the signal is off.

 

attachicon.gifIMG_1754.JPG

 

Just to note that there are two shunts for the headshunt in the photo, but the tall on is the commissioned signal, with the short one being out of use

 

I can't extend the headshunt and I can't move the signal forward (as this would mean locos would be foul of the crossovers. The headshunt works for shorter locos, but I want to be able to stable large locos in there as well.

 

So, what would you do as a signalling solution?

 

I think an off indicator mounted ahead of the signal would do the trick, although in talking with my boss about it, he thinks it's overkill! Whilst I'm not too worried about it being absolutely prototypical, I would like a realistic solution.

 

Simon

Is the joint compliant in the first instance? Find the location where the rails from the common crossing are 6 feet 6 inches apart. Measure back from there 16 feet. Where is the track circuit joint in relation to that measurement?

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Is the joint compliant in the first instance? Find the location where the rails from the common crossing are 6 feet 6 inches apart. Measure back from there 16 feet. Where is the track circuit joint in relation to that measurement?

Whilst I don't think it is prototypically compliant, it is behind the clearance point.

 

Simon

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Hi,

 

This is one for the signalling engineers / designers.

 

On Norwood Road, I have a signal sighting problem with my headshunt, it's too short, just. The situation is this:

 

When I stable Class 67's and 68's in there (and probably 37's, but I haven't tried), the locos are hard up against the buffers and the wheels are behind the shunt signal and track joint, but the cab is in line with signal (see picture below), giving the driver no indication of when the signal is off.

Thats no worse than Exeter headshunt with a 153, the only unit that fits in there, we need to get within 2 feet of the buffers to be behind the signal, but you dont have to because the block joint is a beside the signal, and with the wheels being well back from the front of the unit it isnt a problem, it cant be extended because of the river behind the buffers.

 

On your layout you could extend the headshunt if you wanted to and could even do it in a way to make it look like it has been deliberately extended, or you could leave it as it is and work around the problem.

 

First rule of operation is where is the block joint, as long as the wheels are the right side of the block joint the signal can be cleared whether the train is behind the signal or not.

 

I went out for my unit one morning and the signal was in line with the first passenger doo0r on the 455, the front of the train was about 15 feet the wrong side of the signal, but because the wheels had cleared the block joint (by about 2 inches) it was all good, I just had to stand on the platform until the signal cleared and then return to the cab.

Edited by royaloak
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