A Study in Sussex (Part 14): The Beginnings of Big Changes


With consultation on the much-discussed improvements at East Croydon and Windmill Bridge opened on November 5th 2018, we look briefly at what is being put forward and take the opportunity to provide an update for the plans for the Brighton Main Line.

The much-needed proposed improvements to the Brighton Main Line centre on activity in the East Croydon area. These proposals have been extensively covered in this series of articles. This activity has been noticeable as a very much behind-the-scenes affair. It is true it has captured the interest of our readers, MPs, affected councils and rail users groups but there has been very little involvement of either the passengers or the more general public – until now.

A minor irritation has been that the proposed scheme hasn’t really had an official name, which has led to a long-winded description of what the scheme is when referring to it. This has been rectified in this consultation.

CARS for a better train service

There are those of us who are grateful to Network Rail that the scheme finally has a proper title and, better still, a true acronym. Slightly confusingly, ARS is a fairly standard Network Rail abbreviation and, in this context, it generally means ‘Area Resignalling Scheme’. It is then prefixed by the geographical location of the scheme in question. We have already had WARS (the Waterloo Area Resignalling Scheme). CARS in this case actually stands for Croydon Area Remodelling Scheme. It seems particularly unfortunate that a railway renewal scheme distinctly sounds as if it is something to do with road transport.

For better or for worse, the Croydon scheme will now be known as CARS. It is a capacity improvement scheme of which resignalling is a necessary part but remodelling describes it much better.

The consultation

The first thing to say about this consultation is – don’t get excited by it. This consultation, the first of what is expected to be a series of them, is about implementing disruptive infrastructure improvements in the Croydon area in order to provide long term benefits to rail services. The consultation is presenting the broad outline plan in order for feedback to be provided. Expect the usual notorious graphics from Network Rail explaining concepts and symbolising nothing that can be accurately related to what will actually happen on the ground.

Topics relevant to this particular consultation include the impact of the scheme, in broad terms, on the local community with issues such as over-platform development at East Croydon, station entrances and changes to the local road system. It is not about track layout, exactly what extra services will be provided or specific details of the proposed replacement for East Croydon station.

The consultation could really be summed up in five words: ‘Should we be doing this?‘ Network Rail is clearly hoping for positive (or at least an absence of negative) feedback, but the idea is to get the issue about whether it is a worthwhile scheme established at the outset.

The alternatives

In principle the idea is to compare it with alternatives but it is hard to see what realistic alternatives there are. The only two obvious ones are either to just maintain and renew the current setup and rely on reduced commuting and/or the abandonment of various proposed housing developments in Surrey and Sussex, or to go back to the original suggestion in the London and South East Route Utilisation Strategy a few years ago and plan a tunnel from north of Selhurst to south of Purley.

The obvious problem with the first of these is that predictions of reduced rail use due to technology have always been found to be wide of the mark. It is true that changes have been detected and ascribed to new technology, and that journey patterns have changed, but the demand for rail travel hasn’t gone away.

The lesson from SWR

The one marked change in travel patterns that has been noted recently, on just one comparable railway line, is a slight drop in London suburban traffic in contrast to the increase in traffic (not necessarily 5 days a week) from further afield. As an indication of either more working from home or part-time employment (possibly prior to retirement), the idea that a season ticket should be considered for statistics purposes as equivalent to 10 rail trips per week is starting to get seriously questioned and has probably been a slight over-estimate for a number of years now.

Indeed, if anyone wonders why South Western Railway (SWR), in the past year or so, were not in bigger trouble than they were with a dramatic lull in passenger numbers, it is because the reduction in short distance traffic was partly offset by an increase in more-profitable long-distance commuting. Pertinent to East Croydon, a drop of passenger numbers from inner London doesn’t really affect the viability or benefits of CARS, but an increase in long distance commutes is exactly the sort of rail traffic that would benefit most from the scheme.

In a telling lesson of how fickle rail traffic can be, the SWR has largely recovered from the temporary loss of traffic – except on Fridays. Traffic is projected to increase again with the reasons behind the temporary loss not entirely clear but various explanations (including the effects of strikes) have been put forward. The suspicion though is that the move away from a rigid 5-day commuting week will continue to increase the number of longer-distance journeys.

The tunnel challenge

The obvious problem with the idea of a tunnel is the timescale. That is before we consider the enormous cost and the engineering challenge of underground platforms at East Croydon. A tunnel won’t be built before Crossrail 2, so you are probably looking at 2040 at the earliest. Action is needed sooner. A tunnel might be more appropriate when the signalling next needs renewing and all the lower-hanging fruit has been picked but it is hard to see it as the right solution for now.

The need for renewal

One thing that has become apparent over the past few years is that the railways have an enormous backlog of maintenance and renewal work to catch up on. This is starting to seriously affect reliability. This is particularly noticeable on London Underground but is also prevalent on the former Southern Region of British Rail.

Noticeable in particular is the problems with old tunnels. Modern signalling doesn’t like wet conditions and tunnels tend to be both wet and inaccessible to signal engineers. These often 150 year-old structures, built in an age when some construction issues were less-than-fully understood, are well overdue for some tender loving care. The problem of drainage in Sevenoaks tunnel have only just been fully addressed – probably for the first time ever.

A consequence of the direct route of the Brighton Main Line at its southern end is there are a number of tunnels. Major engineering work is planned for Balcombe, Patcham and Clayton tunnels. This involves not only a multi-million pound cost but also a closure of the southern end of the Brighton Main Line for nine days in February 2019. Other work is also being done or aspired to (such as an extra platform at Gatwick) to ensure a frequent reliable service can operated from Sussex. Clearly this work is of limited value if the trains cannot reliably and punctually travel through East Croydon. Whilst a straightforward like-for-like-renewal in the East Croydon area will go a long way to improving matters, it will also perpetuate existing known problems that would hinder both operation and future development of the Brighton Main Line.

So, looking at the bigger picture, it really makes sense to take advantage of a necessary renewal to expand on it and improve capacity in the East Croydon area. This is particularly so as another opportunity may not present itself for another forty years – and then the land necessary for improvement may not be available then anyway.

The inevitability of disruption

Commuters who may be in a different job in a different part of the country in ten years time may well question whether the disruption will be worth it – and it is certainly a legitimate consideration. There have been schemes in the past that have failed this test early on and generally do not even get heard about by the general public.

It is said that an upgrade for Bank station has been planned for years but no previous proposals could avoid a closure period of unacceptably long duration. It took a combination of necessity, an acceptance that some closure was inevitable and an innovative new plan to finally convince the people in charge that the gain would be worth the pain endured.

On CARS, the planners have worked hard to refine plans and try and minimise disruption. An earlier plan to rely on four platforms at East Croydon during disruption has been improved on and now there will be a minimum of five platforms open. This is actually much better than four platforms. Platform 5 is of limited use in a northbound direction due to signalling overlap restrictions – one of the major issue CARS is intended to resolve. With, effectively, only one northbound track for the ‘slow’ trains there is little to be gained by having two southbound tracks. In contrast, platform 2, the ‘fast’ reversible, is genuinely useful at enhancing capacity and its loss would have been highly noticeable.

Its not just rail disruption

One thing easy for rail-minded people to overlook when thinking of disruption during reconstruction is the effect on the road network. Nowhere will this be more apparent than Windmill Bridge itself which is a road-over-rail bridge that currently spans the five tracks present at that location. The plans require seven tracks and both space constraints and the desire to reduce the closure period to an absolute minimum means that Windmill Bridge needs to be a single span bridge.

The new Windmill Bridge road bridge will be longer than the existing bridge. Due to the difficulty of boring new deep piles in under an existing bridge whilst keeping it open, it will almost certainly of necessity be wider (road width). That is good news for Croydon Council because they can have wider pavements and cycle lanes across the bridge but it also means they need to think about how they will adjust the road layout and, indeed, the local topography.

Windmill Bridge forms part of Lower Addiscombe Road which itself is part of the busy A222. Whilst not a TfL road, its closure would mean more traffic on the A232 (Addiscombe Road) which is run by TfL. Furthermore, the Addiscombe Road is a major bus route onto which four of the busier routes serving areas to the east of Croydon converge. So disruption at Windmill Bridge could have a knock-on effect on bus services in the suburbs to the east of Croydon. Windmill Bridge itself is only served by one single-decker bus route that could easily be diverted.

As well as any potentially disruptive preparatory works, there will inevitably have to be a full road and rail closure of Windmill Bridge in order for it to be rebuilt. If recent experiences are anything to go by, demolition of the existing bridge may be more of a challenge, time-wise, than actually putting the new one in place. Not helping matters is Croydon’s Council’s recent memory of bridge reconstructions (by TfL) that have taken far longer than the council would have wished.

Given that the reconstruction of Windmill Bridge is going to have a major impact on rail services (including providing a rail service from London to Gatwick Airport) and also to local roads (including rail replacement buses for services to Gatwick Airport) one can see that, if not carefully handled, the replacement of Windmill Bridge has the ability to disrupt international air traffic.

Aiming for Christmas 2023

As more and more project development is carried out, problems get identified and an appropriate plan emerges. Given the scale of the disruption that would be involved, the only realistic time to replace Windmill Bridge is Christmas – New Year. If you miss that slot, even by a few days, you have to wait a year for the next one.

You also don’t want to have any plan that is dependent on not encountering high winds during the construction dates because you really don’t want to have to go back for a second attempt or end up with the old bridge demolished and the new bridge not finished. This, in turn, limits the options available. Major Brighton Main Line renewals in the past few years have often coincided with various particularly adverse weather conditions. To that extent, renewals on this line seem jinxed.

Given the time, realistically, to get through all the consultation procedures, prepare the Transport and Works Act Order (needed because the scheme involves land-take) and the probable consequential public inquiry, the development team have pencilled in December 2023 for the replacement work for Windmill Bridge. With Christmas Day falling on a Monday that year, it is probably the best opportunity they will have.

The problem for the planners is that an early start to Windmill Bridge really is on the critical path. Whilst, in theory, you could work on either side of the bridge and join the new tracks together at a later date, this does not lead to optimised railway construction work. The highly-automated track machines like to have a clear run. You also don’t want them getting in the way of passenger trains when they need to travel from one side of the bridge to the other. Basically, until Windmill Bridge has been sorted out, other work cannot commence.

Norwood Junction realisation

Another area where further detailed planning revealed that some modifications of ideas was desirable is Norwood Junction. The previous intention had been to get work at Norwood Junction out of the way before concentrating on the trackwork between there and East Croydon. This would have assisted in terminating some trains short at Norwood Junction to avoid capacity problems at East Croydon.

The more the scheme was worked on, the more it was realised that treating Norwood Junction in near isolation was not a viable option. Changes to the main proposed layout, even quite small ones, could impact on what needed to happen at Norwood Junction. Furthermore, a consequence of this was that once Norwood Junction was in its final state any options for further changes to the main layout would be very limited. Now one might argue that Network Rail should plan properly and not be in this situation but, as Network Rail has found to its cost, the rules can change during the course of a scheme and alterations can be unavoidable.

The plan now is to have six tracks through Norwood Junction with four platform faces at the station. The station would be rebuilt so the dingy subway between the platforms will be filled in and new overbridges built. This in turn creates an opportunity to make the station step-free which will be welcomed by many locals as well as Croydon Council and TfL.

If Norwood Junction station becomes step free, almost all London Overground stations south of Surrey Quays will be step free. Of the remaining four, Penge West is easy to do but requires political willingness and pressure. That leaves Wandsworth Road, Clapham High St and the challenge of Peckham Rye.

East Croydon – lighter

Some of the talk about the scheme early on was about the option of decking over East Croydon station for oversite development. This was obviously attractive to the planners as the financial case for the scheme would improve. This also fits in with Croydon Council’s desire to maximise land use close to (or air use above) the station.

Reality bit home in the form of the consequence of fire regulations for underground stations. A station is classified as underground for fire regulation purposes if more than 50% of the space above the station is enclosed. Even Shoreditch High St (on an embankment) is classified as an underground station by this rule. Having to abide by ‘section 12’ rules (it is still colloquially know as that even though the original rules have been replaced by different legislation) imposes considerable constraints – not least with the evacuation procedures.

The current plan involves ensuring that the station is not subject to more onerous fire regulations. It is still planned that there will be five exits from the station so it is not as if evacuation will be unduly constrained.

It remains to be seen whether passengers waiting at East Croydon will be subject to more noticeable diesel emissions from the Uckfield diesel trains in a semi-enclosed station or whether that problem will have gone away by the time the station is rebuilt.

If East Croydon is partially over-decked it is almost certain that the current foot overbridge will be replaced. Whilst some may be aghast at such expense for a relatively short life, it has to be realised that, with the latest class 700 Thameslink trains arriving, the former subway just could not cope with today’s passenger numbers let alone numbers in the early 2020s.

… and better

A further benefit of more forensic examination of the proposals as time progresses is that the track engineers have found a way to reduce the amount of ‘stagger’ needed in the platforms at East Croydon, with platforms 1-4 no longer located as far north as originally planned. We believe one of the factors making this possible is the exceptional width (for a single track) at the road bridge over East Croydon so that the first set of points can be located further south. Whilst the platforms will not be fully aligned, the offset of platforms 1-4 compared to platforms 5-8 (the existing platforms 3-6) will be substantially reduced.

Although this welcome change will be better for future passengers, we suspect the main reason for the change is to prove more space for the complex set of junctions to the north of the station.

The resignalling quandary

The East Croydon area is currently signalled from Three Bridges Area Signalling Centre (ASC). This is not to be confused with the much more modern Three Bridges Regional Operating Centre (ROC) which, amongst other things, controls the signalling throughout London Bridge and south as far as Anerley. It is the intention that East Croydon will eventually be controlled from the ROC.

A view of the Norwood Junction and Windmill Bridge diagram at Three Bridges ASC

One big issue is how you go about handing over control from the ASC to the ROC. An obvious school of thought is to hand over tracks to the ROC as they get introduced. This though makes supervisory oversight difficult if not everything is controlled from the same location. An alternative is to press ahead with moving everything to the ROC and modify as necessary. But the modern signalling in the ROC is sophisticated and complicated and one doesn’t want to have to keep testing it after every change.

One of the signalling pods at Three Bridges ROC

Although it might sound counter-intuitive, it might be best to continue with the ASC until there are no further modifications. There could still be additions outstanding but these could simply be flagged as ‘out of use’. It is believed that spare parts for the signalling consoles at the old ASC would not be an issue as there would be a stock of redundant parts from similar closed boxes – such as London Bridge. Such a plan to delay moving over to the ROC would mean that it is likely that any intermediate layout could not be used with optimum efficiency as it could not be incorporated into any advanced traffic management or other related software.

Part of the bigger plan

With a finally-grasped realisation by politicians that the Brighton Main Line needs some serious money being spent on it, Network Rail are starting to catch up on the work that needs doing. For them it is a three-pronged attack:

  • Keeping on top of small remedial measures
  • Brighton line upgrade work such as the work this Christmas at Victoria and the nine-day blockade south of Three Bridges in February 2019
  • Long term plans to sort out the major bottleneck (CARS)

Although no particular measures are known, the small remedial measures would include anything within Network Rail’s remit that was necessary to ensure that Thameslink performs well on the current network.

The missing bits

What is, unfortunately, missing from the current plan for the Brighton Main Line is any scheme other than CARS that is not simply renewal. So, crucially, there seems to be no definite commitment to build a third (terminating) platform at Reigate despite originally due to be completed by 2018 or earlier.

The eighth platform at Gatwick Airport station is desirable but unfunded. Even sorting out passenger flow at Victoria, so often talked about, seems to have no funding. The one proposal that may well go ahead, probably with funding from the airport, is further overdecking of Gatwick Airport station to improve passenger flow and capacity.

An update on the track layout plans

Despite reiterating that this consultation is not about track layout, we have taken the opportunity to include our understanding of the latest plans for the layout. This will almost certainly not be the final plan. There are further enhancements desired and the challenge being worked on is to add these in as well without taking away a benefit that is already there.

We have never seen any 3D plans, but it appears more use is made of diving-under rather than having a viaduct on top of a viaduct to achieve the necessary grade separation. A turnback on the approaches to Selhurst depot to assist turn around of trains terminating at Selhurst and returning in back towards Victoria (or Shepherds Bush) has been added. A single long down siding has been added at Norwood Junction. We presume this is for future use by London Overground to enable 6tph to operate on the Crystal Palace and Clapham Junction branches.

First the lull, then the storm of disruption

On current timescales it looks like the Thameslink Programme will be complete and running a full timetable around the end of 2020. Passengers will then have three years of a relatively stable and reliable train service before the next prolonged phase of disruption.

If all goes to plan, by around 2028/9 CARS should be delivering tangible benefits although it will not be fully complete before the early 2030s.

Thanks to ngh for an updated diagram to complement those previously drawn and available in earlier parts of this series

Written by Pedantic of Purley