Prince's Cross

by Tony Elliman

Creating Prince’s Cross (Part 3)

There is still a lot of work to do on the design of buildings, scenery and the “under board" electrics but this is essentially a practical project so this part turns to some initial building work. I began with the main board carrying the station throat from gasworks tunnels to the platform ends. If this doesn’t work as designed then there is no point in fitting the scenic stuff round it.

Board and Base Level Construction

The two 2'6“ by 4' base boards were supplied in kit form by Model Railway Solutions along with sets of legs and boards for the back scenes. This all went together as expected to produce the main scenic area as shown in Figure 1. I also produced two end plates so the scenic boards could be stored or moved face to face. I don’t envisage moving the layout often but having, with my son in the 80/90s, built layouts on fixed bases and then needed to move I am not going to be caught out again.

Figure 1. Initial Scenic Base Board Assembly

The first step was to check the location of key parts to the design - the tunnels, the turntable, Goods Way and York Way (see Fig. 2) before building up the relative scenic levels. Of course it’s going to be a while before details like the Albion, the gasworks and the signal box appear.

Figure 2. Locating Key Bits of the Scene

The basic levels covered by the two road ways and the elevated structures were blocked in using balsa wood and basewood sheets courtesy of Hobby Craft to keep the overall board weight down. The bank down from the gasworks behind Goods way needed a bit of retaining brick wall along the pavement to get it looking right. The final profile was created by filling the voids in the balsa with Gorilla Expanding foam filler and a finishing skin of plaster.

The track work through the tunnels is lower than that in passenger loco by some 4 or 5 feet. To reproduce this I built up the track base with increasing layers of B&Q’s thin polystyrene wood floor underlay. This is conveniently 2.2mm, about 1 scale foot thick. To achieve a uniform surface on the top layer the profile was built “up-side-down” as in Fig. 3.

Figure 3. “Up-side-down" Polystyrene Layering for the Track Gradients

Building up the grade up from the tunnels (1 sheet) to the platform lines (4 sheets) and Passenger Loco (5 sheets) creates a reasonable looking profile for the track bed. I t also requires the creation of a retaining wall to the east of the service area. This was created using a sheet of 1/32 base wood and brick paper inserted between the layers of polystyrene to reach the stage shown in Figure 4.

Figure 4. Track Levels and the Loco Retaining Wall

Track Laying Track laying began with the iconic scissor and slip pattern between the central up and down lines through the gasworks tunnels. This is shown in Figure 5. The polystyrene was painted grey before laying the track using PVA. For this section I tried adding Woodland Scenics fine grey ballast while the PVA was still wet (as the club has on the Aylesbury Town layout).

Figure 5. Starting to Lay Track

I found this “Aylesbury” method doesn’t work so well with the thick plastic base on PECO code 55 track. The layer of ballast achieved is too thin and there are significant problems with sticky ballast getting into moving parts! For subsequent track laying I have not added ballast at the same time.

This board has 4 double slips, 4 single slips, 2 diamond crossings and 11 points! Getting them all to line up with only short bits of track, if any, between them was going to be a challenge! There is a long run of point work starting at the up relief and running south west across all the down lines to the outside platforms 8 and 9. This going to determine where the other lines run and set the angles for access to the milk yards and passenger loco. The priority was to get this line right and then position the other track work from it.

Figure 6. The Key Lines Through the Throat

Figure 6 shows this line from Up Relief right through to the platform 8/9 entry slip. There is a choice here between route C that crosses both down lines or route B that goes about 33 yards on the Down Main before crossing to the Down Slow into the suburban platforms. The other key line of point work is from the Up Main through route A into platform 6.

With tracks diverging and the rejoining some of these lines were tricky to get right and I decided a couple of times to release the adhesive and relay a couple of sections before I was satisfied. Having got the “spine” right I could turn my attention to completing the track work on the north board as shown in Figures 7, 8 and 9.

Having come this far it is time to get under the board (see Fig. 10) and sort out all the point actuators (28) and drop wires (90 odd)! But that is another part of the story.

Figure 7. Station Throat and Gasworks Tunnels from North End of Train Shed

Figure 8. The Trainspotters View from Platform 6 (Departures)

Figure 9. The View from Goods Way

Figure 10. Now for All Those Wires!

Creating Prince’s Cross (Part 2)

The Birth of an Idea

To capture something of the 1960s station, a freestyle model can’t be a perfect design. It needs to reflect this feel of having grown over time so things end up not being in the right place. In my case, for example, the rather awkward moves to get from the main line platforms to the passenger loco service area. I began by studying the track plan and site layout to try and work out how it had grown up over time. Fortunately the S-R-S archive contains working notes tracing the early evolution of King’s Cross.

The Evolution of a Station

The main line station was opened by the London & York Railway in October 1852. Cubit’s iconic train shed and offices at the south end of the site sat between the two lines leading down to the cut and cover underground and the “widened lines” leading to Moorgate.

The original station had just two platforms - an arrivals platform to the east (which is now #1) and a departures platform adjacent to the offices on the west (which is now #8) . The lines in between were used as carriage storage sidings or release lines. The original engine shed was on the north east corner of the main train shed.

The station didn’t last long with so few platforms. By 1871 a couple of the carriage sidings had already been converted to additional platforms. This process continued piecemeal until the late 1930s when the last release line was removed and the main train shed became the eight platform configuration we see today. The odd numbering, 1 to 10 with no platform 3 or 9, persisted until the re-signalling in 1971.

Over the same time the east, suburban side of the station grew up in a series of haphazard extensions. A second shorter, and less ornate, train shed was built at an angle to the main line to house three “suburban” platforms. The locomotive service area remained on the east side but grew to fill the space between the new suburban train shed and the widened Moorgate line platform.

In 1871 the area to the east of the gas works tunnels was a basin on the south side of the Regent’s canal, presumably, for barges bringing coal into the gas works. By the 1920s coal transport had moved to rail and King’s Cross was in need of more suburban platform space. In 1921 plans were drawn up to move the loco service area to the site of the disused basin and add more suburban space. This was built onto the station as an outside island platform between the existing suburban shed and the widened down line.

Figure 1: The Evolution of Prince’s Cross

The series of diagrams in figure 1 shows the fictitious evolution of my station Prince’s Cross mirroring the changes between cubit’s original station and King’s Cross of the early 60s.

The Station Throat

Detailed track plans for King’s Cross covering the 1928 and 1971 re-signalling are available (from John Hinson of the S-R-S) along with many photographs of movements in and out of the station. Studying these led to several iterations of the station throat design.

Having achieved an idea of what the model will look like the next stage is to achieve a design for the station throat which is practical with N-gauge track. It is going to be complex! The prototype makes extensive use of slips within the restricted space between the platforms and the tunnels. It also has a few three (or even four!)-way point complexes.

With such a complex throat either track must be scratch built or built from a range with a good choice of options. Not having scratch built before and with plenty of other challenges the choice quickly came down to code 40 (FiNetraX) or code 55 (PECO). Since code 40 slip profiles were not available design work proceeded using PECO code 55.

Quite apart from the zigzag light engine moves described in part 1 a pattern which stands out in the departures from the west side of King’s Cross is the suburban platform starters (platforms 11 to 16) and the line of five intermediate route signals (A to E) between the loco service area and the signal box at the end of platforms 5 and 6. Each platform has two starters which clear traffic on to just two of the intermediate signals these then clear the traffic on to one of the three down lines. The reduction in scale could have made these intermediate signals redundant in the model. However, retaining them would give it more of the King’s Cross flavour and I have kept three intermediate routes and signals (A to C).

A repeated pattern within the throat is also that of a scissor crossover, often running into slips (see Fig. 2). There is a prominent example of this where the Up Relief and Down Main 2 lines exit the gasworks tunnels. I have repeated this in my design and used a similar arrangement to access the north spur east of the two up lines.

Figure 2: Scissor and Slip Crossovers

Another repeated pattern is in the use of a double slip at the entry to a pair of platforms making them effectively a single movement point at the south end of the throat. In the prototype this occurs with 3&4, 6&7, 12&13, and 14&15. This pattern (see Fig 3) is repeated in the model design for platforms 1&2 and 7&8.

Figure 3: Slip Platform Entries

After several attempts at putting all these bit together I arrived at the layout I needed. This spans two 4’ by 2‘6“ boards with the main train shed running the full length of the right hand board. The track runs from end to end of the two boards so the station frontage and plaza will go on a small trackless extension to the right (south). To the left (north) the scenic space ends with the gasworks tunnels running into the fiddle yard.

Creating Prince’s Cross (Part 1)

The Birth of an Idea

Way back in 2010 as I was approaching retirement I decided that a good project for the coming years would be to fulfill my ambition to construct a model railway. I had started a couple of times with my son in the 80s and 90s but he never shared my enthusiasm and I was holding down a demanding job. However, there were some personal issues to deal with first and I only really got started in 2016 when I was living in a therapeutic community. Of course I couldn’t actually build anything at that stage but I could start planning.

One of the first questions is how big will the layout be? Not knowing where I would be living when construction started I had to make some assumptions. Single and on a company pension somewhere with two bedrooms seemed the most likely outcome. At least one of them would be designed as a double and finding somewhere with at least 3 meters along one wall looked like a safe bet. Allowing for some sort of off scene turn into a fiddle yard would give a scenic length of 2.5m. Again assuming access would be limited to one side I set a target of 0.7 to 0.8m for the base board width.

The next question is what sort of layout will it be? What are my priorities? The thing that grabs my attention in a model is the operation - trains coming and going- so I want a layout with a variety of possible movements. It needs to be a busy station or yard. The other area I want to focus on is it being a “signalman’s” layout. In the days of manual signalling the big four employed about as many signalmen controlling the network as they did drivers moving the trains. With no access to the “back” and the fiddle yard off to the side this narrowed my choice down to some sort of terminus.

Since I had spent much of my early teens trainspotting at the north London stations my thoughts turned to King's Cross at the end of the steam era in 1960. In those days King’s Cross was a pretty big station - significantly bigger than it is now. The main line platforms are about 1000 feet (2 meters in British N). It was also 15 platforms wide with a line under York road to the east and the parcels and “milk yards” to the west. To fit my space limits it would need to be a freestyle design of something similar; but smaller. Thus, since princes are small kings, it became “Prince’s Cross”.

Figure 1:The King’s Cross Site

Getting the “Look and Feel” of King’s Cross

I want to give Prince’s Cross the “look and feel” of Cubit’s station south of the Regent’s canal with the same pattern of traffic movements. To capture something of the 1960s station, my freestyle model can’t be a perfect design. It needs to reflect this feel of having grown over time so things end up not being in the right place.

Throughout its life King’s Cross has been hemmed in between major existing structures - the gas works, the canal, and the York and Euston roads. All of the expansion of the station has been on the west side of the site - away from the main line platforms and up lines through the gasworks tunnels. Each addition or extension has had to be a compromise between the ideal and what is possible. By the 1960s the station and track work were not well organised for its mix of diesel and steam traction providing a varied range of services.

This is what will make Prince’s Cross an interesting challenge to operate as a signalman’s layout. Only one of the up lines through the gasworks tunnels can reach any platform. The plodding suburban diesel trains heading up to town have to cross all the down lines to get to the suburban platforms. Also to get to the service area steam engines have shunt ahead on the down main and then run back into the Milk yard before reversing again into the service area. The platform rationalisation in 1971, rerouting Thameslink through St. Pancras and now (2019) plans for a major over haul of the approach from Belle Isle all go to show just how far the 1960s station was from the ideal. To remain in keeping with the prototype I have needed to study the way it had been evolved over the years and then repeat the process on a smaller scale. Any similarity between the back story I have dreamed up for Prince’s Cross and the prototype King’s Cross is not entirely accidental!

Scaling Things Down

Working from detailed track plans for the King’s Cross re signalling in 1932 and 1971 along with photographs of movements in and out of the station has led to several iterations of the station design. This is a point where ambition and the practicality of building the model come into sharp conflict!

Rather than build track work from scratch I decided to work with the PECO code 55 profiles .It took several attempts to come up with a feasible looking design that captured some thing like King’s Cross with its routing through signals A to E on the west side of the station. (In my final design these reduce to only three routes - A to C).

A critical question was whether to retain the underground link to Moorgate (more recently known as Thameslink)? This could be modelled by creating down ramps and looping the line back under the base board as shown in figure 2. Using a passing loop in the underground section would mean trains don’t need to come back in the order they left.

Figure 2: Modelling the Moorgate Line

Much as this would be visually and operationally exciting I decided that the added complexity of the station throat and construction might just be a step to far!

Cubit’s main line train shed is about 214 feet wide. If the 75cm target for the model is to be achieved this needs to come down to about 100 feet or so (21cm). Each double line will be about 5 cm and a 20 foot wide platform needs 4cm. Some unforgiving arithmetic led me rapidly to just put four mainline platforms under a single arched roof.

The rest of the site also needed to be similarly reduced to about half the scale of the 1960 station. The seven suburban platforms on the west side needed to come down to about three. This reduced the station to the scale of Marylebone but that is still credible as as a small London main line terminus.

The prototype suburban train shed was gloomy and when modelled would be difficult to see into. I, therefore decided that Prince’s Cross would have only one internal suburban platform and the other two would be modelled on the 1920s external island platform and canopy. In like manner the milk yard and loco service area were both reduced from four lines to two.

In the 1960 prototype six approach lines ran through the gasworks tunnels. The question then was how many of them should be retained for Prince’s Cross? The signalling diagrams for King’s Cross show that several of the tracks can only reach a part of the station as listed in Table 1.

Table 1: Comparison of routes through station throat area

In addition to the tunnels movements to and from the north end of the site can also be from the north spur (home for the station pilot) or to the loco service area entry road. These are also included in Table 1.

To model these quirks will need more than two lines through the tunnels. Having already dropped the York Road platform excluding the up slow line was an easy decision. The other easy decision was to exclude Down Main 2 which effectively duplicate Down Main 1.

At this point some consideration needs to be given to loco movements between the service area and the main line platforms. In the prototype these involve shunting ahead on one of the two Down Main lines. They must then run into the milk yard before finally reversing into the service area. The choice of Down Main 1 or 2 allowed the signalman a valuable option to keep these light engine movements clear of departing traffic.

With the loss of Down Main 2 the model has lost this option. The only alternative is to set back on the Up Relief but in the prototype that is the only up route into three quarters of the station. To compensate for this my Prince’s Cross design allows the Up Main to access all main line platforms instead of just the eastern half of the station.

Figure 3: Prince's Cross Track Plan