A Study In Sussex Part 7: East Croydon

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Regular followers of this series will be aware we started our look at the Brighton Main Line by working our way down from London. Until now we we have been looking at what have turned out to be relatively minor problems holding back capacity improvement on the Brighton Main Line. When we get to the vicinity of East Croydon, however, it all changes and we really get to the heart of the issue of capacity on the line.

Busy, busy, busy

When thinking of places with very high numbers of daily train movements one naturally thinks of Clapham Junction. East Croydon may not match that but it is very busy and, unlike most services serving Clapham Junction, there is a lot of complexity as trains get sorted out in order to be routed to their ultimate destination.

Number of Daily Train Movements

A carefully chosen selection of locations showing daily train movements.

In an attempt to drive home the point about how busy East Croydon and Windmill Bridge Junction are, the recently published draft Sussex Route Study contains a chart showing the number of daily train movements at various locations. Network Rail clearly chose to omit one or two of the busier locations of the former Southern Region but nevertheless it does show East Croydon and Windmill Bridge Junction (which it defines as “the junction north of East Croydon where the lines to London Victoria and London Bridge diverge”) being significantly bigger than various well known iconic places. Possibly the most relevant is Reading where the whole complex, recently rebuilt to eliminate the worst pinch point on Great Western, only has two thirds the daily train movements that Windmill Bridge Junction has.

It all centres on East Croydon

It is hard to overstate the importance of the proposed work at East Croydon that is currently scheduled to take place around 2022-2023. The situation can be starkly stated as follows: if you don’t sort out East Croydon there is really no point at looking at any of the other major planned schemes for the Brighton Main Line. We will qualify this just a bit in a moment but the absolute need to sort out East Croydon is a basic premise that is guiding Network Rail’s thinking.

For trains coming up from Brighton, East Croydon is the final station before the route diverges to Victoria and London Bridge. Furthermore, it is also effectively the station where everything from all the branch lines to the south finally comes together. South Croydon could possibly make a similar claim, but ultimately there the fast and the slow lines are quite separate.

It follows from the previous paragraph that anything that affects the railway between Windmill Bridge Junction and South Croydon can have a potentially paralysing effect on the entire Brighton Main Line service. This isn’t just a hypothesis. For a good account of one occasion when this actually happened read pages 8-10 of the October 2011 issue of Rail Engineer. On that occasion the disruption was due to a water main leak. Indeed what this article didn’t really highlight was that it was not just the railway that was affected – there were other knock on effects as well. For if the railway doesn’t function then everyone takes to the roads to get to Gatwick and this tips the road traffic level up to the point where the result is huge congestion in outer South London.

Even when things are running normally East Croydon remains very much a critical pinch point and the obvious desire for the future is that it should no longer remain so. With this in mind Network Rail have already carried out a lot of mitigation work to try and ensure that a single point of failure does not, wherever possible, knock out both the fast and slow lines through this critical section of railway.

This belief that East Croydon is the main problem around which everything revolves is also backed up by the last London & South East Route Utilisation Study. We reported at the time that the study seemed rather defeatist. It suggested that there was no short or medium term solution for the East Croydon problem and placed its long term hopes on approval for a tunnel from south of Purley right the way to central London through which relief tracks could run. Clearly this would be many decades away and with rapidly rising passenger numbers some people in Network Rail must have realised there was no conceivable way they could wait for a tunnel that might never come.

Problems elsewhere are relatively easily fixed

We have seen in part 4 that some improvement in capacity can be made at Victoria relatively easily. We have also seen in part 5 that issues at Clapham Junction can be partially solved by letting nature take its course and eventually more modern signalling, ETCS (European Train Control System), will improve matters. If that were not enough to solve Clapham Junction’s capacity issues on the Brighton Main Line fast lines then there are other things that can be done, although quite major work would be involved. In part 6 we have seen that at London Bridge it is not the terminal platforms that will be the constraint.

So with a couple of minor exceptions, and rather like a wonder cure, Network Rail is taking the attitude that whatever the problem with the Brighton Main Line, the first part of the solution is to sort out East Croydon. The exceptions mainly centre around Redhill. There are a few local problems that can be cured with an extra platform (platform 0) at Redhill that should be operational by 2017. This will also allow improvements to the Reading – Gatwick service which of course does not go anywhere near East Croydon. Nearby, a proposed new terminating platform at Reigate will at the very least give more operational flexibility regardless of what happens at East Croydon.

Not just East Croydon itself that was the problem

So far we have been very lax with our terminology and have bundled an awful lot of things together and called them “the East Croydon problem”. We really need to be more specific and clearer. The problem really is one of trains calling at East Croydon and passing through various junctions just north of East Croydon where the line splits to Victoria and London Bridge. The most critical of these junctions is one mentioned earlier – Windmill Bridge – but references to Windmill Bridge often really refer to the whole set of junctions. The larger area is sometimes referred to as the Gloucester Road triangle. As always Carto Metro assists in identifying the location and the surrounding area, but on this occasion it really cannot do justice to the complexity of the layout.

The area has long been associated with transport but originally it was the Croydon Canal that was dominant. References to specific locations north of East Croydon may well have come from that era but are not helped by referring to locations that no longer exist. Windmill Bridge itself falls into this category. One would have thought identifying the location of a former windmill would be easy enough but there were in fact four windmills in the vicinity according to a local history archive. It is even more unclear as to what bridge was originally being referred to but the current bridge taking the main road over the railway tracks is known as Windmill Bridge and has been for around 150 years.

And don’t forget West Croydon

We also have to be aware that whilst the focus is on East Croydon there is also the issue of trains that serve West Croydon which, of course, include London Overground services. Most trains from West Croydon are all-stations to either London Bridge or Victoria. There are a few fast trains, however, to and from London Bridge in the peak hours so the track layout also has to cater for these.

A history of track layout change around East Croydon

Historically East Croydon was not a big problem. In the very early days steam trains used to come up from the coast and divide at East Croydon with one portion going to Victoria and another to London Bridge. Quite remarkably, the whole area was semaphore signalled until 1954. Southern Railway had four aspect signalling installed in the critical inner London areas in the 1920s and the company was very aware of the benefits of four aspect colour light signalling schemes covering critical junctions. It is surprising therefore that the East Croydon area was not tackled sooner and that it was not already signalled with four aspect signalling before the Second World War broke out.

1954 layout

The layout from 1954 to 1983

In 1983 there was a major resignalling scheme involving substantial track modifications. With an increase in long distance traffic from Surrey and Sussex and a generally declining suburban demand it made sense to sort out the issue of the fast lines. On the London Bridge side the fast lines were (and still are) the centre two of the four tracks. With the platform layout at stations between Norwood Junction and New Cross Gate as they were there was virtually nothing that could be done there even if one wanted to. With the Victoria fast lines being the two westernmost tracks from Selhurst to Victoria it made a lot of sense if the westernmost tracks at East Croydon were also fast lines. Until 1983 this was not the case.

1983 layout revision 2

The 1983 (current) layout. Changes are shown in red.

Until the 1983 resignalling the western most tracks at East Croydon (platforms 1 and 2) weren’t fast lines – they were the slow lines. In a manner reminiscent of the London Bridge scheme of 1976, the 1983 scheme meant that trains on their inward journey would be largely sorted much further out into slows and fasts. This would have been done by Stoats Nest Junction which is just north of Coulsdon. In fact prior to 1983 this was already happening but the lines then crossed again north of East Croydon largely undoing the good work of separation that had already been done. What happened in October 1983 was that the fast and slow lines were swapped between Stoats Nest Junction and the Gloucester Road triangle.

At East Croydon the separation of services would be complicated somewhat by trains that were regarded as slow trains south of East Croydon but fast trains north thereof. This is still the situation today. In simple terms a slow train, or at least a train occupying the slow tracks, south of East Croydon today will either start or terminate at South Croydon or call at either Oxted or Purley.

The 1983 resignalling scheme was a big logical improvement and was probably the right scheme for the time but, inevitably, the need for more capacity, in part brought about by other improvements, means that it is no longer particularly suited to today’s needs let alone in future years when the Thameslink Programme is complete.

Some of the problems are ones that can be found in many places on the railway already and are partly explained by growth in passenger numbers. East Croydon station has the issue of dwell time, and hence platform occupation time, which has increased over the years. Longer trains mean more of an issue with signal overlaps made worse by the short distance between East Croydon platforms and the Gloucester Road triangle. In the meantime signalling standards have imposed more restrictions on what can be achieved by improved signalling using the current track layout.

The problems of the fast tracks

The track layout around East Croydon has some particular issues. Two particular problems concern trains in the up direction that occupy the fast tracks all the way from south of East Croydon to London or vice versa.

The reversible fast line is rather limited in capacity when used in both directions which it generally is. Using it in both directions also means that one cannot plan moves in one direction without taking into account any consequences this might have for trains travelling in the opposite direction. Obviously an extra line would potentially allow complete segregation. This would mean in a northbound direction a following train would not have to wait for the previous train to clear the platform before being able to enter the station. In the southbound direction trains from London Bridge and Victoria could enter East Croydon station simultaneously – as they sometimes do now.

The junction where the fast trains to and from the south split to go to Victoria or London Bridge, Windmill Bridge Junction, is currently a flat junction. Actually it best considered as two flat junctions – one for the fast lines and one for the slow. These flat junctions inevitably lead to issues of capacity and the knock-on effects of a train arriving late.

Slow to Fast – the worst of them all

Possibly the worst problem of all relates to the trains that serve the slow lines south of East Croydon (platforms 4, 5 and 6) but are fast north of East Croydon. There are a number of problems associated with these services which are basically the Horsham starters, the Oxted Line trains and the Caterham and Tattenham Corner trains that are fast from East Croydon. In the case of the “Cats and Tats” there is a big incentive to combine these at Purley to reduce the number of these trains.

The first real problem is that platforms 5 and 6 form an island at East Croydon. This means that, to avoid making things too awkward for passengers, it would be much simpler if platform 4 could be designated the up platform and platform 5 only used for down trains and the occasional terminator despite being notionally the slow reversible. Having just one up platform for the peak period slow trains at a station as busy as East Croydon is quite a restriction.

Changing from slow to fast train at East Croydon is bad for all Victoria services because the only way to get to the fast lines to Victoria is by occupying the slow lines just south of Selhurst, albeit briefly, in the process of doing so. The junction is entirely flat so this is quite a restricting move.

The previously described awkward way of getting from platform 4 to the fast up Victoria line can be circumvented by simply crossing on the flat just north of East Croydon station. Indeed, in the off-peak, if a signaller spots an opportunity to do this in the up direction, especially if the train is late, he may well do so and thereby knock a minute or two off the journey time.

A further problem is encountered in the up direction when a slow train at East Croydon proceeds to the fast line to London Bridge. It has to cross the down Victoria slow at Cottage Junction and then it has to occupy the slow line to London Bridge before swapping over to the fast by the time it gets to Norwood Junction.

Limited slow trains

Looking at the slow trains arriving at East Croydon is not especially relevant to Sussex issues but one has to remember that, according to our definition at the start, the trains that start at East Grinstead, Uckfield and Horsham (all in Sussex) run on the slow lines on their approach to East Croydon from the south.

Whilst the number of fast trains serving East Croydon is reasonable and the number of slow trains from Sussex that run fast from East Croydon northward could be described as adequate, the remaining number of slow trains (the all stations trains) is really very low considering. To make matters worse one of “slow train” services is the direct service to Milton Keynes which doesn’t serve central London and is really only a slow service (as far as Clapham Junction) because there is no realistic way to run it fast to Clapham Junction.

The paucity of slow services is not through lack of demand but simply because of the conflict between fast and slow services. So, currently, the only way to increase the number of slow all-stations services is to cut down on the number of fast services – or at least services that are fast north of East Croydon. So provision of fast and slow services are related and any solution to the East Croydon problem – even if only intending to improve the fast services – needs to look at both the fast and slow services.

Croydon as a centre in its own right

A further consideration when looking at a suitable service to be provided in the area is to recognise that Croydon will attract a lot of people travelling to East Croydon in the morning. Currently there is a lot of redevelopment going on and that and the future shopping redevelopment – with all the extra jobs this will bring – will only add to that. On top of that, East Croydon is, of course, an obvious place to change at when making longer journeys e.g. to Gatwick Airport.

It is surprising how many stations not very far away (e.g. West Norwood, Crystal Palace) do not have a direct service to East Croydon in peak hours. Even somewhere like Forest Hill has only a very limited half-hourly service to East Croydon in the peak period. Of course for many of these stations there is a service to West Croydon which will be an acceptable alternative for many. Nevertheless there are clearly many services that could be provided (and in some cases were provided in the past) if only the capacity were there.

More Platforms

Although not a solution in itself, a fairly obvious requisite for a solution is the need for more platforms at East Croydon. The obvious desire is for an additional two platforms and a reallocation of what currently exists. If an extra island platform could be added then the platforms could be very neatly arranged as follows:

  • Platforms 1 & 2 – up fast
  • Platforms 3 & 4 – down fast
  • Platforms 5 & 6 – up slow
  • Platforms 7 & 8 – down slow

In practice this new island platform (1 & 2) would have to be located on the west side of the station very slightly further north than the existing platforms to enable the necessary tracks to pass under the road and tram overbridge that is outside the main entrance to East Croydon station.

Such a platform arrangement as listed above would more or less solve the dwell time issue as the two up fast platforms (1 & 2) would both serve the single up fast line from the south. Similarly the down fast platforms (3 & 4) would serve the single down fast line to the south.

On the eastern (slow) side it would be more complicated with the four platforms (5 – 8) at East Croydon serving the slow lines to South Croydon of which there are three. It would resolve the current issue of only, effectively, having one up slow platform as in future both platforms 5 and 6 (currently numbered 3 & 4) would serve the up slow (and reversible slow in the up direction).

A better Junction with more grade separation

Both the existing and the future track layout at East Croydon requires getting one’s head around, but in essence it involves replacing the flat junction where the down fast Victoria and the up fast London Bridge have to cross with a new grade-separated junction and a new flyover (London Bridge fast flyover) so that the fast lines are completely separated from the other lines.

NR proposed CP6 solution revised

Network Rail’s proposed solution for implementation in CP6.

What follows from the above is a clever bit of reuse. There is currently grade separation in the vicinity of Cottage Junction which was built in 1983 to enable the slow lines to Victoria and the up slow to London Bridge to pass over the fast lines to and from London Bridge (which of course are to and from the current platforms 1 – 3). This will then be partially reused to provide grade separation for the slow lines.

But not perfect

Sadly one thing the proposed scheme really does not address is the issue of trains on the slow side of East Croydon (future platforms 5 – 8) travelling fast to and from Victoria. These will still have to effectively switch between the slow and the fast lines just south of Selhurst station. It is hard to see how this can be avoided. What it probably does mean is that in future there will be a reluctance to provide any service fast from East Croydon to Victoria beyond the minimum necessary that calls at Purley or originates from (or terminates at) East Grinstead or Uckfield. The latter is not a problem because Uckfield trains, which are diesel, do not normally run to Victoria. Passengers on the East Grinstead, Caterham and Tattenham Corner lines will probably encounter extreme resistance to running more fast trains to Victoria should they press for it. Purley passengers will probably welcome the new journey opportunities that Thameslink will provide but also find a deteriorating service of fast trains to Victoria.

The other limitation of the revised scheme is that there only two tracks on the slow lines north of East Croydon – as far as Windmill Bridge Junction. This would appear to be unavoidable but a pity. At least in future if a Victoria down slow train was brought to a stand at Windmill Bridge Junction it would not be affecting other services.

Land Take

One thing that further complicates the scheme for enhancing East Croydon is the need for land take. This is not for the station itself where Network Rail has at least safeguarded its own land so that with a bit of adjustment it can fit the necessary eight platforms in – more about this in a future article – but for other elements of the new layout.

Land take can greatly complicate a project even if the amount taken is tiny. This is especially true if residential property is involved. Of course if you can simply buy the land that makes life much easier. The 1983 scheme required land but as this was owned by Croydon Council, who was willing to sell, this was not an issue.

Network Rail has not said what land needs to be taken but knowledge of the area would suggest that a number of houses in a row of old railway terraced cottages in Gloucester Road may be needed. Assuming that this is correct, whether these could be purchased by agreement and how many would actually need to be demolished (as opposed to have part of their garden taken) is unknown. Of course if compulsory purchase were necessary that may trigger a public inquiry which would have to be factored into the timescale.

It is not only the railway cottages that may need to be subsumed to provide land necessary for the desired layout. There are also some very low grade industrial outlets just to the west of the track northwards from East Croydon and it is expected that some of that will need to be made available for any new scheme. On top of that an aerial view shows that an additional arch needs to be created or opened up in Windmill Bridge (a road overbridge) itself and this in turn may well necessitate a small diversion of Gloucester Road away from the railway cutting.

Pictorial Description of the location in question

Windmill Bridge looking north

A view from the current Windmill Bridge (Lower Addiscombe Road) looking north towards Windmill Bridge Junction.

The above picture is taken from the bridge by the junction of Addiscombe Road and Gloucester Road. On the other side of the parapet to the left is Gloucester Road. Windmill Bridge Junction on the fast lines (the three leftmost lines) can be clearly seen protected by signals. Under NR proposals there would be a fourth fast line to the left of the existing tracks.

Windmill Bridge looking south

A view from the current Windmill Bridge looking south towards East Croydon.

The above picture is taken from the other side of the road. The new platform would be to the right of the picture and an new track will be added the right of the existing tracks. The demolition of the building in the foreground would seem inevitable. If one were to assume that the road overbridge were to remain without being rebuilt then the track would have to be slightly further to the east (right) in order to line up with an existing bricked up arch.

More Overground to West Croydon?

It makes sense while looking at East Croydon to look at a proposed enhancement suggested by TfL which is intended to make it possible to increase the London Overground service to West Croydon from 4tph to 6tph. The exact track layout shown to achieve this is a bit speculative but it is based on official comments made. We are looking at it as if it were a separate scheme but in reality, if it were implemented, it is believed that this would be done at the same time as the rest of the East Croydon work in order to further recapitalise on resignalling that would need to be done anyway.

Further proposed TfL changes revised

An educated guess at TfL’s proposed enhancement to enable extra LO trains to terminate at West Croydon.

We do know a few useful facts which means that this scheme appears to fit in with future Overground plans. We know there is a strong desire to increase services northbound London Overground from Sydenham by 2tph in the morning peak as “pixie busters”. We also know that these will initially originate from Crystal Palace even though West Croydon is preferred. This is because there is not the capacity at West Croydon so the idea of increasing the capacity of West Croydon for London Overground trains makes sense.

We also know that the 2050 Transport Supplement appendix suggests that the East London Line core should be upgraded to automatic train operation of a type known as ERTMS which is the same type as will be implemented on the Thameslink core. This would happen around 2023 which neatly fits in with the West Croydon enhancements. This may well suggest 6tph to both West Croydon and Crystal Palace. It would appear that the long term objective may be to run 6tph on each of the four branches south of the core – New Cross, Clapham Junction, Crystal Palace and West Croydon.

What Next?

Although East Croydon is very much a post-Thameslink Programme project, the railways have a long lead time and one suspects that teams in Network Rail are beavering away at working out the costs of the proposed East Croydon upgrade right now.

The way the railways currently work is by dividing the future into five year control periods. The next control period is CP6 which runs from 2019 – 2024. The government allocates a certain about of money for each control period depending on the case put forward for relevant schemes. So, to complete the work around 2023 Network Rail need to have the funds awarded to do the job at the start of CP6. To get these funds they need to present their case to the DfT by 2016. In planning terms that is not far away.

It would probably not be an exaggeration to say that East Croydon will be the most important location-specific application made for funds in CP6 in the London Area. Seeing as pretty much any proposals for improving the Brighton Main Line rely on the work at East Croydon taking place there is a lot riding on this and it is very important for Network Rail to make a good case.

In fact, one aspect of one other really important proposal for CP6 (the digital railway) is probably also highly desirable to improve the Brighton Main Line. As a congested railway the Brighton Main Line would benefit a lot from implementation of the European Train Control System (ETCS) and the overlaid European Railway Train Management System (ERTMS). It follows that the funding available in CP6 and what it is allocated to is going to be of crucial importance to the Brighton Main Line.

There are (more) bad times just around the corner

If all goes to plan it seems that, by the time the Thameslink Programme is complete and fully bedded down, South London commuters will be bracing themselves for another major burst of disruption. Passengers will have to settle for being grateful for their few years of relative peace starting around 2019.

This will probably also impact on franchising. If the level of disruption is as great and as impossible to predict as expected, one can see that the largest potential franchise may well revert to a management contract (as it is today) as no private company would be prepared to take the risk without a suitably large financial incentive to do so.

KO3?

The Thameslink Programme had a preliminary project phase called Key Output 0 then two major phases – KO1 and KO2. There was a pause between the two main phases which was largely down to the Olympics. One can argue that the work due to be done at East Croydon is not really Thameslink specific but then Thameslink currently affects far more passengers than those that just use the Thameslink services. Maybe we should think of the work proposed at East Croydon as Thameslink KO3 and brace ourselves for the levels of disruption we have come to associate with Thameslink. At least the developments at East Croydon, if they go ahead, will unlock the potential for significant and much needed capacity increases. In future articles we will look at these potential capacity increases elsewhere.

Many thanks to ngh for drawing all the diagrams.

Written by Pedantic of Purley