Leeds City Wellington is John Elliott's accurate EM gauge portrayal of the ex-Midland Railway location as it existed at the end of the '50s. An overview of the layout can be found in the four videos on John's Youtube channel
A vital aspect of the whole layout is that operationally, everything is done as closely as possible to the real thing - thus we work to the real 1958 working timetable (and we run it at real-time speed - if we can keep up with it!) and all aspects of signalling are worked in accordance with what we understand to have been real local practice; though our knowledge of that continues to evolve. This has involved the construction of lever frames with full mechanical and electrical locking for the boxes on the "scenic" part of the layout along with replica block instruments, bells, control circuitry etc which replicate the working of the Midland Rotary Block and Controlled Block systems as appropriate. All this was described in 3 editions of Model Railway Journal - numbers 283, 285 and 286.
All very fine, but anyone with experience of large and busy layouts will be aware that it is the design and operation of the "hidden storage" aspect which presents the greatest challenge to the modeller and on John's layout, there are four "fiddle yards" representing Leeds City South (Leeds 'New' station), Whitehall Junction (to the North), Engine Shed Junction (to the South) and Farnley Junction on the ex LNWR "Viaduct" line. The latter two are physical connected and operated from a common control panel by two operators. The operators in each of these areas face a difficult enough task receiving, marshalling and despatching the trains without the handicap of working a complicated track plan unaided by any interlocking and so it has been necessary to develop solutions to give them the most powerful possible tools for the job. Therefore, in keeping with the 'as real as possible' theme, I have designed and built eNtry eXit style panels for each of these areas.
The first of these was for Leeds City South, representing Leeds West power box which works AB to Farnley Junction and TCB with slots on signals and points to Leeds City Junction. It was done using relays to perform the required functionality ie route-selection, interlocking, panel display, external controls (track circuits, block controls, slotting) etc for the 23 points/slips and signals. In use, the operator presses and holds the eNtry button, then presses the eXit button which completes the circuit to the required relays via the diode matrix 'logic'. After the passage of the train, the route is cleared, either automatically via the track circuits, or by the operators via the Clear Route buttons. This returns the controlling signal to Danger and releases the locks on the points, however, these retain their position until a conflicting route is set. This minimises risk to the trains from an inadvertent route cancel.
With over 150 individual relays and 200 diodes, the design of custom PCBs was essential to minimise hand wiring and these were manufactured by JLCPCB in China using our supplied Gerber files generated using the free KiCad software. The panel itself was made from MDF by John using his Laser to create all the cutouts for the track display, signal and track circuit LEDs, push buttons etc. After three years in use, it has proven very useful and - after an initial intermittent fault due to a dry joint - very reliable.
The second panel is for the Whitehall Junction Storage Siding area. This is a complex layout with 34 point ends and 112 possible routes with anything up to five in operation simultaneously. My original thinking for this was to use the same relay-based solution as described above to control just the "running lines" with the 18 storage roads being treated as a simple "fans of sidings" using a simple cascade of relays. However, it was realised that, to minimise the burden on the operators, it was really necessary to provide complete route selection and interlocking throughout the whole area. All this meant that a relay-based approach was just too complex and so the decision was taken to "go digital" using a microcontroller (single board computer) approach: the computer chosen being from the "Arduino" family based on the extent of support available.
Lest anyone should misunderstand, "digital" in this context is NOTHING to do with DCC technology, data packets etc: this is good old firm-coded-bit-bashing!!!
Any computer-based system depends on being able to provide sufficient input and output (I/O) connections to link the processor to the real world and for this we used 74HC165/575 Shift-register parallel/serial/parallel chips along with (because we wished to operate at 12v for compatibility with the rest of the layout) opto-isolators and ULN2803C amplifiers. Since we required a lot of channels, we again used custom designed PCBs but this time also had them populated with SMT chips in China. Each board gives up to 256 channels of input or output ('infinitely' expandable). Additionally, we designed and had populated a number of PCBs for the track indication LEDs, push button mountings etc which provide the panel functionality. This saves a huge amount of soldering, but was not cheap, and for 'next time' a cheaper solution has been produced.
The processor itself is a Teensy 4.1 - which uses the Arduino programming language and toolkit but is much more powerful and - unlike the Arduinos - blessed with sufficient memory for all the required data. The programme has been written in C (though I may yet re-write it in C++ to make it more transportable) and the necessary (and large!) data tables are created in MS XL, then copied and pasted into the code.
In operation the panel works pretty much like the prototype eNtry/eXit panels - except for much simplified cancelling arrangements - pressing an eNtry button causes it to flash - indicating that at least one route is available from it - then pressing the eXit button, sets the route (provided it is not locked), clears the signal - which backlocks all the points on the route - and illuminates the route on the panel. Additionally, the relevant Cancel button flashes red to indicate how the route will be cleared in the absence of track-circuit cancellation. A number of "Shunt" routes - which are bi-directional - are available and these require the buttons at both ends to be simultaneously pressed. In the second phase, full control via the block instruments will be provided but this feature currently remains to be implemented. These controls will link into the existing controls for the Rotary Block (to Leeds City Junction) and Controlled Block (from LCJ) on the Fast and Slow lines.
After 12 months operation the panel has been very successful. The only issue has been that occasionally, after power up, the processor boots up in a highly unstable state This is usually cured by a re-boot or two, but a cause has proved illusive and therefore the processor is left permanently running for the moment.
The third panel operates the combined fiddle yard for both Engine Shed and Farnley Junctions. This panel has been completed and bench-tested, but there has not yet been any opportunity to test it on the layout - though this should happen in the next few weeks. Although this fiddle yard is physically slightly smaller than Whitehall Junction, it is no less complicated to work, and in an ideal world, a panel of exactly the type described above would have been used to provide the same functionality. However, the track layout in this yard is rather compromised by limited space and John is not convinced that the current layout will not be subject to change - a decision not to be taken lightly and requiring more experience of working the current timetable. Rather than wait for this however, a "generic" panel has been designed which will be very easy to reconfigure to any future changes. Whilst this cannot provide the full functionality of a "proper" panel, it does go, say, 70% of the way and involves perhaps only 30% of the effort to build and program.
In operation the operator presses the button at the entry end of a route, and, if a route is available, the adjacent LED will flash. Pressing the button at the end of a valid route will cause the entry-end button to light steadily and the points and signal to be set. Once that is complete (there are small time delays so that several servos do not all fire at once), the exit-end LED will also illuminate along with the relevant Cancel button which flashes red. Clearly, in the absence of track indications, it is up to the operator to remember which route is represented by which pair of lights and that is not so easy when five routes are active at once as in the photo! Still, that is a lot easier than working individual points!!!
Again, the basis of the system is an Arduino type micro controller (a Teensy 4.0 in this case), and again uses custom-designed PCBs to provide the 64 output channels required. However, the panel has been simplified to the bare minimum - just 32 multi-purpose buttons and 32 LEDs. These are simply arranged in two pairs of columns and the track diagram (printed on A3 paper) is "bent round" to fit the buttons rather than the other way round. Thus, in the event of a change to the trackwork, all that is needed is to re-print the diagram and reconfigure the data to suit the new layout - nothing else needs changing.
Internally - apart from vastly simpler wiring - the functionality is provided in exactly the same way as the Whitehall Junction panel. One key difference however is that, being 'generic', no provision is made to receive any inputs directly from the layout and therefore 12v input compatibility is not required. This enables the panel to use logic-level voltages and therefore a matrix-scanning approach (using a 4x8 matrix for 32 buttons) is used which simplifies the input requirement to a single 74HC165 (for the 8 'rows') plus four output pins on the Teensy to provide the four 'columns' of the matrix. Along with the vastly reduced number of panel indications, this greatly simplifies the wiring (and the cost) of the panel.
The change to a matrix scan, plus the fact that most of the buttons are "dual purpose" (ie can function as both an entry and an exit button), demands a degree of modification of the code used for Whitehall Junction but this has proved to be minimal and there is a 95%+ compatibility between them.
I realise that there is lot to take in there, but I hope it will be of interest in that it gives people an idea of what can be done and also a realistic view of what is involved in making such equipment (let no one tells you it is "easy"!!!).
If there is interest, I would be happy to go into a little more depth as long as no one expects a step by step recipe - after all, these approaches are a bit too advanced for beginners and not every layout requires such comprehensive solutions. However, the 'generic' panel above, having potential wider application, might be worth further explanation.
Best wishes,
Howard
A vital aspect of the whole layout is that operationally, everything is done as closely as possible to the real thing - thus we work to the real 1958 working timetable (and we run it at real-time speed - if we can keep up with it!) and all aspects of signalling are worked in accordance with what we understand to have been real local practice; though our knowledge of that continues to evolve. This has involved the construction of lever frames with full mechanical and electrical locking for the boxes on the "scenic" part of the layout along with replica block instruments, bells, control circuitry etc which replicate the working of the Midland Rotary Block and Controlled Block systems as appropriate. All this was described in 3 editions of Model Railway Journal - numbers 283, 285 and 286.
All very fine, but anyone with experience of large and busy layouts will be aware that it is the design and operation of the "hidden storage" aspect which presents the greatest challenge to the modeller and on John's layout, there are four "fiddle yards" representing Leeds City South (Leeds 'New' station), Whitehall Junction (to the North), Engine Shed Junction (to the South) and Farnley Junction on the ex LNWR "Viaduct" line. The latter two are physical connected and operated from a common control panel by two operators. The operators in each of these areas face a difficult enough task receiving, marshalling and despatching the trains without the handicap of working a complicated track plan unaided by any interlocking and so it has been necessary to develop solutions to give them the most powerful possible tools for the job. Therefore, in keeping with the 'as real as possible' theme, I have designed and built eNtry eXit style panels for each of these areas.
The first of these was for Leeds City South, representing Leeds West power box which works AB to Farnley Junction and TCB with slots on signals and points to Leeds City Junction. It was done using relays to perform the required functionality ie route-selection, interlocking, panel display, external controls (track circuits, block controls, slotting) etc for the 23 points/slips and signals. In use, the operator presses and holds the eNtry button, then presses the eXit button which completes the circuit to the required relays via the diode matrix 'logic'. After the passage of the train, the route is cleared, either automatically via the track circuits, or by the operators via the Clear Route buttons. This returns the controlling signal to Danger and releases the locks on the points, however, these retain their position until a conflicting route is set. This minimises risk to the trains from an inadvertent route cancel.
With over 150 individual relays and 200 diodes, the design of custom PCBs was essential to minimise hand wiring and these were manufactured by JLCPCB in China using our supplied Gerber files generated using the free KiCad software. The panel itself was made from MDF by John using his Laser to create all the cutouts for the track display, signal and track circuit LEDs, push buttons etc. After three years in use, it has proven very useful and - after an initial intermittent fault due to a dry joint - very reliable.
The second panel is for the Whitehall Junction Storage Siding area. This is a complex layout with 34 point ends and 112 possible routes with anything up to five in operation simultaneously. My original thinking for this was to use the same relay-based solution as described above to control just the "running lines" with the 18 storage roads being treated as a simple "fans of sidings" using a simple cascade of relays. However, it was realised that, to minimise the burden on the operators, it was really necessary to provide complete route selection and interlocking throughout the whole area. All this meant that a relay-based approach was just too complex and so the decision was taken to "go digital" using a microcontroller (single board computer) approach: the computer chosen being from the "Arduino" family based on the extent of support available.
Lest anyone should misunderstand, "digital" in this context is NOTHING to do with DCC technology, data packets etc: this is good old firm-coded-bit-bashing!!!
Any computer-based system depends on being able to provide sufficient input and output (I/O) connections to link the processor to the real world and for this we used 74HC165/575 Shift-register parallel/serial/parallel chips along with (because we wished to operate at 12v for compatibility with the rest of the layout) opto-isolators and ULN2803C amplifiers. Since we required a lot of channels, we again used custom designed PCBs but this time also had them populated with SMT chips in China. Each board gives up to 256 channels of input or output ('infinitely' expandable). Additionally, we designed and had populated a number of PCBs for the track indication LEDs, push button mountings etc which provide the panel functionality. This saves a huge amount of soldering, but was not cheap, and for 'next time' a cheaper solution has been produced.
The processor itself is a Teensy 4.1 - which uses the Arduino programming language and toolkit but is much more powerful and - unlike the Arduinos - blessed with sufficient memory for all the required data. The programme has been written in C (though I may yet re-write it in C++ to make it more transportable) and the necessary (and large!) data tables are created in MS XL, then copied and pasted into the code.
In operation the panel works pretty much like the prototype eNtry/eXit panels - except for much simplified cancelling arrangements - pressing an eNtry button causes it to flash - indicating that at least one route is available from it - then pressing the eXit button, sets the route (provided it is not locked), clears the signal - which backlocks all the points on the route - and illuminates the route on the panel. Additionally, the relevant Cancel button flashes red to indicate how the route will be cleared in the absence of track-circuit cancellation. A number of "Shunt" routes - which are bi-directional - are available and these require the buttons at both ends to be simultaneously pressed. In the second phase, full control via the block instruments will be provided but this feature currently remains to be implemented. These controls will link into the existing controls for the Rotary Block (to Leeds City Junction) and Controlled Block (from LCJ) on the Fast and Slow lines.
After 12 months operation the panel has been very successful. The only issue has been that occasionally, after power up, the processor boots up in a highly unstable state This is usually cured by a re-boot or two, but a cause has proved illusive and therefore the processor is left permanently running for the moment.
The third panel operates the combined fiddle yard for both Engine Shed and Farnley Junctions. This panel has been completed and bench-tested, but there has not yet been any opportunity to test it on the layout - though this should happen in the next few weeks. Although this fiddle yard is physically slightly smaller than Whitehall Junction, it is no less complicated to work, and in an ideal world, a panel of exactly the type described above would have been used to provide the same functionality. However, the track layout in this yard is rather compromised by limited space and John is not convinced that the current layout will not be subject to change - a decision not to be taken lightly and requiring more experience of working the current timetable. Rather than wait for this however, a "generic" panel has been designed which will be very easy to reconfigure to any future changes. Whilst this cannot provide the full functionality of a "proper" panel, it does go, say, 70% of the way and involves perhaps only 30% of the effort to build and program.
In operation the operator presses the button at the entry end of a route, and, if a route is available, the adjacent LED will flash. Pressing the button at the end of a valid route will cause the entry-end button to light steadily and the points and signal to be set. Once that is complete (there are small time delays so that several servos do not all fire at once), the exit-end LED will also illuminate along with the relevant Cancel button which flashes red. Clearly, in the absence of track indications, it is up to the operator to remember which route is represented by which pair of lights and that is not so easy when five routes are active at once as in the photo! Still, that is a lot easier than working individual points!!!
Again, the basis of the system is an Arduino type micro controller (a Teensy 4.0 in this case), and again uses custom-designed PCBs to provide the 64 output channels required. However, the panel has been simplified to the bare minimum - just 32 multi-purpose buttons and 32 LEDs. These are simply arranged in two pairs of columns and the track diagram (printed on A3 paper) is "bent round" to fit the buttons rather than the other way round. Thus, in the event of a change to the trackwork, all that is needed is to re-print the diagram and reconfigure the data to suit the new layout - nothing else needs changing.
Internally - apart from vastly simpler wiring - the functionality is provided in exactly the same way as the Whitehall Junction panel. One key difference however is that, being 'generic', no provision is made to receive any inputs directly from the layout and therefore 12v input compatibility is not required. This enables the panel to use logic-level voltages and therefore a matrix-scanning approach (using a 4x8 matrix for 32 buttons) is used which simplifies the input requirement to a single 74HC165 (for the 8 'rows') plus four output pins on the Teensy to provide the four 'columns' of the matrix. Along with the vastly reduced number of panel indications, this greatly simplifies the wiring (and the cost) of the panel.
The change to a matrix scan, plus the fact that most of the buttons are "dual purpose" (ie can function as both an entry and an exit button), demands a degree of modification of the code used for Whitehall Junction but this has proved to be minimal and there is a 95%+ compatibility between them.
I realise that there is lot to take in there, but I hope it will be of interest in that it gives people an idea of what can be done and also a realistic view of what is involved in making such equipment (let no one tells you it is "easy"!!!).
If there is interest, I would be happy to go into a little more depth as long as no one expects a step by step recipe - after all, these approaches are a bit too advanced for beginners and not every layout requires such comprehensive solutions. However, the 'generic' panel above, having potential wider application, might be worth further explanation.
Best wishes,
Howard
