Aberdeen Kirkhill T&RSD

[5BarVT]

23 hours ago, Flood said:

A totally unrealistic scenario but is was still good fun to run...

Their successors got to Aberdeen so why not!

Paul.

[Dunedin]

I haven't posted on here for a while, but I'm hoping we will have some exciting news to share with you in the near future. I've been asked to submit costings to take Kirkhill to a major show this autumn. The organisers have a lot of planning to do and so I'm not going to steal their thunder at this stage, but it's good to know that we're in the melting pot for what will be the layout's first outing since Taunton in October 2019.

[Dunedin]

I've been progressing a few improvement projects for the layout recently. The first one I'll tell you about, because it's independent of the other two, is the new HST power car repair/maintenance shed. When I say new, it isn't really; it was a lockdown project from April 2020, when I started to build a new shed for something to do.

 

The shed during construction back in 2020:

 

Cladding applied, still to be primed and painted:

 

It's been sat on the worktop in my project room ever since, without a plan to utilise it. Towards the end of last year, it occurred to me that we could add further interest to the operation of the layout by swapping power cars on the HST sets that arrive on the depot for servicing. Back in the days when I worked at Craigentinny Depot in Edinburgh, power car changes were a nightly occurrence, with a target of five per week off exam or repair (usually engine repairs), plus additional swaps between sets for positioning moves, so they finished at the required location the next night (or subsequent nights) to be taken off there for exam etc. Although power cars were allocated to a home depot, Maintenance Control at York would balance out the workload between depots, so you would occasionally get a foreign power car for repair if we had one that was approaching completion and there wasn't a home power car in need of attention or in the right place. Keeping the service running reliably was a balancing act between getting power cars to their scheduled exams on time and removing power cars with defects from service before they became too much of a liability.

 

Given that Kirkhill is largely fictitious and would not have been the size that it is anyway in a location such as Aberdeen - it has a large maintenance shed and a wheel lathe - it wouldn't have had a power car repair shed either, but so what? It's our layout and it would add interest, so on that basis it seemed worth a shot. I realised that if I shortened my lockdown shed, it would fit on a dead-end road at the north end of the depot and these roads don't tend to be utilised that much anyway. The idea was to have the shed, with an inspection pit, with lighting and jacks and other equipment such as would be found in a typical power car maintenance facility.

 

As I said, as originally built, it was one bay too long, so I had to remove some of the cladding and glazing, cut sections of the plywood out and then glue it back together again and reapply the cladding etc.

 

The following photos show how it's turned out thus far.

 

Trying it for size at the north end of the layout:

 

Preparing the ground, Peco inspection pit cut into the baseboard:

 

Ground works nearing completion:

 

View from the public viewing side, power car in position between the lifting jacks (Bachmann Scenecraft):

 

Interior with overhead and pit lighting, but without interior fittings etc.:

 

View from the entrance to the shed:

 

External view:

 

Future improvements will be the addition of workbenches, lockers and general equipment - all from West Hill Wagon Works Ltd, who make some excellent 3D printed items. I also intend to have a flatbed articulated Swift's truck delivering overhauled bogies from Crewe, as used to happen following the move to component exchange maintenance in the late 1980s.

A friend and I are also investigating the possibility of fitting a loco lifting system to simulate a power car being lifted on the jacks for underframe attention / brake disc renewal - which was a frequent overnight activity before the introduction of BSI one-piece brake discs.

More of this in the future. 

Edited March 15 by Dunedin

[Andy Keane]

That's a really lovely model - well worth adding in my view.

In one of your photos there is a little set of steps beside the loco - where did they come from or did you scratch build them - I could do with similar. Thanks Andy

[Dunedin]

15 minutes ago, Andy Keane said:

That's a really lovely model - well worth adding in my view.

In one of your photos there is a little set of steps beside the loco - where did they come from or did you scratch build them - I could do with similar. Thanks Andy

Thanks Andy - much appreciated as always.

Graham built the access platform and steps from a kit a few years ago and it was in the original shed for ages - he can probably remember where it came from.

It wouldn't have been very practical in the main shed in reality, because that has side pits so the access platform couldn't have reached the side of any rolling stock before it fell into the side pit! It's much better where it is now, so it justifies all the work of incorporating the new shed.

[Andy Keane]

2 minutes ago, Dunedin said:

Thanks Andy - much appreciated as always.

Graham built the access platform and steps from a kit a few years ago and it was in the original shed for ages - he can probably remember where it came from.

It wouldn't have been very practical in the main shed in reality, because that has side pits so the access platform couldn't have reached the side of any rolling stock before it fell into the side pit! It's much better where it is now, so it justifies all the work of incorporating the new shed.

My carriage shed needs a set of mobile access steps and I have been wondering how best to model them.

[Flood]

20 minutes ago, Andy Keane said:

My carriage shed needs a set of mobile access steps and I have been wondering how best to model them.

Pete Harvey etches.

https://phd-design-etchings.co.uk/products/ols/products/4mm-mobile-depot-inspection-platform

 

I shortened the original to match a photo posted by @Bob Reid of the inside of Inverness carriage shed.

[Flood]

And the ongoing joke on Kirkhill is that the new HST maintenance shed is actually for one of these:

 

 

🤣🤣🤣

[Dunedin]

When we rebuilt the layout in 2016/2017, we added some signals on the mainline and around the depot exits, but initially they were non-working. The mainline signals were three-aspect Berko models and for the depot exits we had three-aspect Berko ground signals, similar to those I remember on the Craigentinny departure roads. I had also bought some Eckon ground position light signals for shunt moves. I located the signals where I thought was reasonable and didn't think much more about it for several years. It was one of those projects that I would get around to eventually.

 

"Eventually" occurred a couple of years ago now, and I got the signals working at the same time as I upgraded the auto-operation and route setting, such that when a route was set, it also set the signals and they then reverted to red after the passage of a train. At the time, I thought that was pretty cool and added an extra dimension of realism to the operation of the layout. That was until we had a visit by one of our friends who works for Network Rail and also another who is a driver. They pointed out everything that was wrong with the signalling scheme. Anyone who knows me and also understands that one of the objectives of Kirkhill is to make the operation as realistic as possible (if you forget the fact that it's fictitious and over-developed for a Depot in Aberdeen!), then you would also know that this would niggle away at me (which it did), until eventually I decided that something had to be done about it.

 

To explain, it's first necessary to understand the actual layout at Craiginches and the signalling scheme there as it is (or was) in real life. Graham supplied me with the following screenshot:

 

On Kirkhill, we don't have the Down Sidings, so A63 signal and 107 points don't exist, but we do have representations of signals A57, A62 and A58. A65 is assumed to be beyond Wellington Road Bridge due to space constraints.

Our layout plan and interpretation of this is shown below:

 

 

The north end depot departure signals AK09 and AK10 replace A13 signal on the real-life plan. In our original scheme, AK60 and A65BR didn't exist.

Those who have seen Kirkhill in operation will know that when we run the overnight part of our sequence and also on Sundays, we close the Down Main for a civil engineering possession and run trains bidirectionally on the Up Main. In order to facilitate this, our A57 signal has a route indicator on it to indicate that points 25A & 25B are reversed.

So far so good, but as our friends in the knowledge pointed out, part of the reason for having a second means of access to a depot in real life is to enable continued access/egress in the event that the main connection becomes unusable for any reason. We included the south end connection because we have a train that departs to the south each morning. We rarely brought anything onto the depot via that connection and when we did, the setup was such that A57 Signal again had its route indictor illuminated, which in reality it wouldn't.

 

In the real world, what would happen is that to allow northbound trains from the Down Main to access the depot, A57 Signal would have subsidiary calling on signal beneath the main aspects - two white lights or cats eyes. These would indicate authority to pass the main aspect at red for a move onto the depot which then becomes permissive, under control of the depot yard staff and the driver must be prepared to stop and obey their commands. The move then takes place via points 25A & 25B and points 28A & 28B into the depot.

 

In the event of the north end depot connection being unavailable, trains would also be brought into the depot from the north on the Up Main via the south end depot connection. To do this, A62 Signal would also have a sub' signal below its main aspect. This would give the driver authority to pass the main aspect at red and to proceed as far as a Limit of Shunt board, positioned far enough beyond the points such that the rear end of the train would clear them. The signal I've denoted as AK60 because it doesn't exist in real life, would then allow the train to set back into the depot via points 28A & 28B, once again under control of the depot yard staff.

 

I said above that A65 Signal is off-scene in our representation, the other side of Wellington Road Bridge, but the line curves through the bridge, so signal sighting would be poor. It therefore seemed reasonable that a banner repeater (A65BR) might be provided to give the driver an indication of whether the signal is off or on, thus reducing SPAD risk, hence A65BR being shown on our plan, before the bridge.

[Dunedin]

44 minutes ago, Flood said:

And the ongoing joke on Kirkhill is that the new HST maintenance shed is actually for one of these:

 

 

🤣🤣🤣

It's known as the giraffe house due to it being tall and narrow 🤣

[Dunedin]

Berko and Eckon don't make the types if signals we need, but I came across Absolute Aspects at one of the Warley NEC shows a few years ago: https://absoluteaspects.com

You can specify more or less any type of UK mainline signal and they'll build it for you - so I did.

In reality, A57 is a 4-aspect signal, so that's what I specified, with route indicator and sub' signal. A62 was spec'd as a three aspect with sub' and I also ordered the banner repeater for A65 which would be A65BR.

After a month or so a very nice box arrived in the post:

 

With some even nicer contents.

The signals themselves:

 

and the circuit boards and connectors necessary to install them:

 

All that was needed then was to install them. How hard could that possibly be?

[Dunedin]

How hard? Well the first thing to note is that these signals have multipin connectors that need to pass through a rectangular hole in the baseboard to mate with the sockets on the baseplates which mount under the baseboard, whereas the Berko signals just had a flat plastic base that you pined to the baseboard surface. All that was necessary was a hole in the board to allow the wires to pass through.

Cutting the rectangular hole is a bit of a nuisance, but it's ok except where there's something below the board surface.

In the case of A62, there was:

 

When we added the mainline, we widened the original boards by adding a 9 inch extension to the rear of each board. The mainline runs along the new board, but A62 was right above the join between the new and the old boards. With only a few wires to pass through, it was possible to fudge it by drilling a hole at an angle. That wouldn't work for a rectangular slot. I ended up buying multitool to cut out the original gusset below the board to make way for the mounting circuit board.

Eventually it all went in.

 

A62 installed, just reballasting to do to complete:

 

For A57, the installation was more straightforward, but getting it to work was another matter entirely...

A57 installed, ballasting still to be completed:

 

With the original Berko signals, I had used Traintech signal decoders because they were relatively cheap and simple to install and set up. They are designed to work anything up to a 4-aspect signal and have two DCC bus addresses, each one on or off, giving four possible outputs. They can therefore be used for a 4-aspect signal, 3-aspect, 3-aspect with route indicator etc. I was able to set up the decoder for A62 without much trouble. I knew that for A57, with it being 4-aspect also with a route indicator and position lights things would be different, but I thought a second decoder would work: one would be used for the four aspects, the other for the position lights and the feather. Wrong! Traintech don't design their decoders to work like that it seems, so I was getting all sorts of strange combinations.

After a bit of research and help from Digitrains, I ended up buying a Yamorc YD8116 switch:

 

This is a very configurable decoder which can be set to operate just about any signal from any country and one of its configs is UK signalling and it will drive a UK 4-aspect signal with route indicator and sub'. You set all this up using a Windows pc interface, so it makes the configuration process relatively simple. Unfortunately the instructions don't tell you a great deal more beyond that and the videos on YouTube manage to leave out some key aspects of the set up which if you don't know about them, you don't know about them and will take you some considerable time to deduce.

I had situations where when I wanted a certain aspect, I had alternately flashing yellows and feathers which is not a valid aspect in the UK, if anywhere.

This is where taking a break and getting two brains on the job is better than trying to continue and beating your one head against the wall.

Cue arranging for Graham to join me the following day and heading out for a walk in the meantime.

What the walk did was allow my brain to work out that I had two problems: one with the signal and one with the Yamorc switch. The signal problem was partly due to what I had asked Absolute Aspects to design for me: Normally their signals come with the circuit boards fitted with the appropriate dropper resistors to enable the signal to operate from 12V dc, so each LED has a 2.2k Ohm resistor in circuit. The Traintech decoders don't require resistors because all that is done internally within the decoder so the additional resistors would cause the aspects to be too dim. I had therefore asked Absolute Aspects to exclude the resistors from my circuit boards. Also their signals are also normally wired common negative whereas most decoders are common positive, so I had asked that they wire mine common positive, which they did. Additionally though, Absolute Aspects also design their circuit boards such that each aspect has its own dedicated terminal, so instead of a double yellow requiring connections to both yellows, it only requires one. The subsidiary calling-on lights also illuminate the red aspect. Absolute Aspects achieve this by using a series of diodes. The configuration for the Yamorc assumes that these are all wired separately, so that was one problem identified. The only difference is that it's possible to get the route indicator with any aspect - in theory (even red). In reality, I wasn't getting a route indicator at all with any other aspect. By removing the diodes I managed to get the arrangement to what the Yamorc design assumes is the starting point.

 

The Yamorc provides a 12V dc output at its terminals, so I had needed to put a 2.2k resistor back in again, which I had done on the common positive wire, so all aspects had the same resistance. Some of the aspects the signal will provide via the Yamorc is flashing yellow, flashing double yellow and the above with route indicator. When I had them flashing alternately, this was because the yellow LEDs require less current to illuminate them than the white ones. When the yellow was switched on, most of the current passed through them and not enough went down the white path to illuminate the whites - there are more whites. When the yellow(s) went out, there was no alternative path so the current flowed through the whites and illuminated them. Once I'd understood this, I put different values in each leg until I got the brightnesses where I wanted them.

 

But why was I getting flashing yellows at a all when I expected a steady aspect?

That was where the next day with Graham came in: There are so many possible outputs from the switch to drive the signal that it needs two accessory addresses to be called up for each aspect. This is easy enough when it's done via a controller such as the NCE Minipanel which I'm using for all of this, but you need to know what addresses and states (on or off) to command. It turns out that the order in which you send these commands to the switch is critical - and in some cases it's the opposite to what the instructions in the Windows configuration table imply. Once again, if you don't know this, you don't know it and will only find out if you follow a very structured process of trial and error - which is where having two of us on the job was invaluable. Once I understood what was going on, the rest was reasonably straightforward. Big thanks to Graham here for his help with this, working out how many different combinations we could have and for double checking my keypad entries on the cab when we were testing it. His maths degree came in useful after all 🤣😂

[Dunedin]

The Yamorc has 16 switchable outputs. It needed 6 for signal A57, so that left plenty over to do something else with. I used the next three to control AK60, the position light ground signal for the move from the Up Main into the depot.

Signals A57 and AK60:

 

That left the banner repeater, A65BR.

Originally, I thought I would just site this on the curve, somewhere before the bridge like this:

 

The more I thought about it, the less happy I was with this arrangement. It wasn't a good angle for seeing when viewing the layout from the public viewing side and it was a little too close to A57, so moving it nearer to the bridge would be better. The problem was that when I built the bridge - in a hurry back in 2017, trying to get the layout finished in time for the Derby Roundhouse exhibition that May, I'd put a retaining wall there, with no room for any signal. That would mean remodelling the cutting, which also meant remodelling the bridge. More of that in a subsequent post, because that has become another project in itself!

The banner repeater looked much better with the reprofiled cutting and sitting in front of what would become the bridge abutment wall:

 

Once again I found that the Traintech decoders were unsuitable for the banner repeater: it was too dim, despite it also having no resistors when I specified it. Unfortunately, these can only be supplied wired common negative at the present time, so I couldn't drive it directly from the Yamorc switch. What the switch can do though is provide an on/off output. This is intended for controlling lights on a layout, but there is sufficient current to drive a relay, which in turn is used to control the banner repeater which is then fed from the 12V dc supply on that baseboard, via appropriate dropper resistors.

[Dunedin]

How does all this work in practice?

Here is a video showing A57, with the route set for the transition from Down Main to Up Main, with approach control. This is all set up to run automatically, when that route is selected from one button on the panel:

 

 

[Andy Keane]

That is an epic development on your signals. Have you thought of writings this up for an article in the MERG Journal. They are looking for content and I think many people would enjoy a full piece on this work.

Andy

[Dunedin]

4 hours ago, Andy Keane said:

That is an epic development on your signals. Have you thought of writings this up for an article in the MERG Journal. They are looking for content and I think many people would enjoy a full piece on this work.

Andy

Wow, thanks Andy!

I had thought this might be content for an article in some publication at some point. To be honest, I hadn't thought about MERG, mainly because this is mostly using proprietary parts and where I'm having to use logic for decision-making (i.e. which aspects get displayed for which route conditions), I'm doing it using relays rather than electronics because I understand relays. I know it could be done much more neatly with some integrated circuits and AND or OR gates. Unfortunately, the NCE Minipanel can't do "if-then-else logic". If it sees an input, it just runs the appropriate macro that corresponds to that input. You have to make the decisions about which inputs to give it elsewhere.

I have some friends and former colleagues who are electronics engineers and who I know would help me with this, so there's much more to do to iron out some of the anomalies that I have at the moment.

 

[Dunedin]

One example of an anomaly is where a train is sitting in a section beyond the signal, so in theory it shouldn't be possible for that signal to display any aspect other than red. I'm using block occupancy detectors to detect the presence of the train, which they do. These can be linked to an input on the NCE Minipanel to revert the signal to danger when it sees the input from the block detector. If a train enters that section, the block detector switches on and the Minipanel detects this and runs the macro to revert the signal. If the train is already just sitting there, although the block detector detects it, the Minipanel doesn't react and it is possible to select that route again and clear the signal. This is because the inputs are being scanned for changes of state - the processor is looking to detect a falling edge as the input is grounded. If it's already grounded, there's no change of state, so the input is ignored. My solution at the moment is to have the block detector drive a relay and the state of its contacts determine which input on the Minipanel is grounded when you attempt to select the route. If the relay is energised (normally open contacts closed), you get a proceed aspect. If it is de-energised, the normally closed contacts are closed and you can only get a red. Those relay contacts are connected to different inputs and those inputs determine which macro gets run when you press the route button.

 

This works ok until I start interlocking the signals with the points. The signal aspect depends on the way the points are set and until the points have changed, and the appropriate contacts which detect their position have changed state, it's possible for the system to decide to display the incorrect aspect on the signal. Once the points have changed, if you press the route setting button a second time, because the point detection contacts are now in the correct position, the system will now display the correct aspect. Once an operator knows the trick is to press the route buttons twice, I suppose it's ok, but it isn't intuitive and it's a fudge and I don't like fudges. For me, this is a fairly significant area for improvement. For exhibitions, operation needs to be as mistake-proof as possible. Whilst at the moment it's good, it isn't where I want it to be, so watch this space. There's more to run on this topic.

[Andy Keane]

I am really enjoying reading this thread. I have built an interlocking system for my tiny layout using an Arduino so I appreciate the difficulties. But I also had help from @The Stationmaster, @5BarVT and @Harlequin to keep me on the straight and narrow. I shall definitely seek you all out when you start exhibiting again. Terrific.

[Dunedin]

2 hours ago, Andy Keane said:

I am really enjoying reading this thread. I have built an interlocking system for my tiny layout using an Arduino so I appreciate the difficulties. But I also had help from @The Stationmaster, @5BarVT and @Harlequin to keep me on the straight and narrow. I shall definitely seek you all out when you start exhibiting again. Terrific.

Thanks Andy and please do come and see us.

[Dunedin]

It's interesting how explaining the difficulties I'm having to someone else helps clarify what the issues are to me too and assists with coming up with a solution. I've realised that what I need for my incorrect signal aspects is a timing circuit. This would be arranged such that when the route selection button is pressed, it grounds the Minipanel input to set up the route and starts the timer, but doesn't ground the input for the signal. After a pre-determined time to allow the route to have set, the timer expires and grounds the input to set the signal. As this will occur after the route has set, it will select the correct signal aspect.

 

Simples! 

[Andy Keane]

50 minutes ago, Dunedin said:

It's interesting how explaining the difficulties I'm having to someone else helps clarify what the issues are to me too

I find exactly the same - somehow just setting things down really helps order my thoughts. I wrote an article on my signal frame for MERG and it made me realize there were a couple of things I had not thought about until I started typing. I am currently writing up my block instruments and again it is helping.