A Study in Sussex Part 9: East Croydon Revisited
We thought we had covered East Croydon in ample detail in recent articles. We also thought we would not be revisiting there for a long time yet. That was until the final version of the Sussex Route Study was published recently by Network Rail. Some significant revisions to the proposed track layout at East Croydon buried in appendix B mean it is probably a good idea to look at East Croydon again.
As with many aspects of the Brighton Main Line, indeed any main line, a change at one location may mean changes are needed elsewhere. This is particularly true for East Croydon. The more flexible layout now proposed may mean that other proposals for elsewhere to help sort out the trains before they get to East Croydon may be unnecessary. Conversely, the greater flexibility may mean greater overall capacity which in turn may mean that other ideas, previously not thought of any great benefit, could now become worthwhile. As such we really need to look at these proposals now because they may have an impact on issues relating to topics that will subsequently be covered in our trip down the Brighton Line.
In Part Seven of A Study in Sussex we saw how absolutely critical the junctions north of East Croydon would be in future when considering reliability and capacity. A once in a generation opportunity tied with essential resignalling presented itself and Network Rail was keen to substantially enhance and improve the layout. The proposals were a great improvement but, as was pointed out, the new layout did very little for trains from the slow (eastern side) of East Croydon transferring to the fast line to Victoria and vice versa.
The revised plans are a significant improvement on the ones in the draft study. They are also more complicated. To try to fully comprehend what we think is going on we will break the proposed track layout down into various component parts before putting it all together to give the complete picture. For convenience we are going to start at the south and work north.
Unlike previously, we are going to try to identify how the bridge at the south of the station fits in with all this. Network Rail’s diagrams are not helpful here but their study was about capacity rather than supplying the finer details of construction. It follows that we cannot guarantee we have got everything about this, or anything else, correct.
George Street Bridge
The first big change to the plans is that it appears that seven tracks will pass under George St/Addiscombe Road bridge just to the south of the station. There are currently six tracks there (as can be seen on Carto Metro) but it does seem to be the case that seven tracks are just about possible. Indeed this seems to be confirmed by the National Library of Scotland map site which has a map showing seven tracks there in the past.
We have four gaps between the spans of the bridge – or rather bridges, because there are actually two distinct bridges, with East Croydon tram stop on the deck of the northern one. The first three gaps (west to east) are of double track width and there is a final gap of single track width on the eastern side. Currently the second gap has only one track through it. In order to get a second track through, some modifications to the current platform 3 would appear to be necessary. If the ramp from the station ticket hall to the platforms were made less steep (as is believed to be intended) and the current platform 3 were extended slightly northwards then there would not appear to be any problem in putting a second track in.
An arrangement with four slow tracks coming in from the south into the four future slow platforms (platforms 5 – 8) would seem ideal as this would involve no pointwork between these platforms and the bridge. This would mean that the platforms could stay in their current locations – or be moved only very slightly northwards.
Fast lines through the station
Whilst the slow lines can neatly line up with the slow platforms as they go under George St bridge the same cannot be said of the proposed fast platforms. Four are proposed and it is only possible to route three fast tracks under the bridge. To fit in all the desirable pointwork for the level of flexibility now desired it will be necessary to move both future fast platform islands northwards. This means moving future island platform 3 & 4 further northwards and probably moving the future island platform 1 & 2 further north than originally planned. The amount could be in the order of 100 – 150m, which is quite significant given a 6-car train on Southern is normally around 120m long.
Fortunately the new footbridge is sited quite a way to the north of the platforms. This had previously provoked complaints for being located too far north, but may well turn out to be vital if the fast platforms are rebuilt north of their current position.
Whilst siting the fast line platforms to the north by a significant amount would seem to be quite a disadvantage to passengers who use the main concourse, it could at least mean it will be possible to provide a bit more circulating area at the top of the resited ramps. More circulating area on the paid side of the barriers could well be useful as East Croydon had yet another separate gateline installed in the past year or so. This is located on the west side of the main ticket hall and faces towards to the town centre. It is located at the top of the existing ramp leading to the current platforms 1 & 2 which, although an improvement on the former arrangements, isn’t really ideal as there can be conflicts of passenger flow around the top of the ramp.
With the extra fast track underneath the bridge and the future fast platforms further to the north, it becomes possible to reorganise the fast tracks in a much better way. Basically there will be more pointwork to the north and the south of the platforms to allow more flexibility. The grade separation where the tracks are lined up to continue to and from Victoria or London Bridge will be achieved much as it is today at Windmill Bridge Junction.
The revised layout allows for a trailing crossover to be installed between the future lines 2 and 3 north of the station bridge but south of the fast platforms. It is this which suggests the distance that the platforms will shift northwards will be considerable. Although there are good reasons for the relocation of the fast lines platforms and the change does have some advantages, as already explained, one can’t see commuters being very happy about the extra distance involved in order to get to the platform.
The diagram below shows just the fast lines and the fast line grade separation. Unlike previous diagrams in earlier articles we have shown the overbridge to the south of the station. It must be emphasised that the exact location of crossovers (north or south of the bridge) is our perception of where they will have to be located, rather than something deduced from a Network Rail document.
Slow Lines though the station
We can now look at the slow line through the station and slightly to the north.
Immediately to the north of the station the slow lines reduce to two tracks (one up and one down) as in earlier plans, but further along the up track diverges to provide an additional track. This means that just north of the bridge taking Lower Addiscombe Road over the railway there will be seven tracks. From west to east they would be:
Up Fast Victoria, Up Fast London Bridge, Down Fast London Bridge, Down Fast Victoria, Up Slow, Up Slow to Up Victoria Fast Spur, Down Slow.
The Up Slow to Victoria Fast spur
The fact that the Up slow now diverges means there is more opportunity for grade separation. So it is now possible to find a conflict-free route for trains from the new platforms 5 & 6 (the current 3 & 4) to get to the Victoria Up Fast line. This is a major improvement and eliminates one of the weaknesses of the earlier proposals. There are up to 18tph on the Victoria Down Fast line and removing the need for trains to cross this on the level is a significant benefit.
The grade separation is not so complete in the opposite direction as we shall see. Whilst this grade separation would be desirable it is not as critical as in the up direction, as in this situation it is the Up Victoria Slow that has to be crossed on the level and this would normally have a maximum of 8tph.
In a northbound direction it is vital that fast trains to Victoria do actually go on the fast lines, otherwise they will be stuck behind a stopping train with no opportunity to switch to the fast tracks until Balham – and yet again that would be on the level. Southbound the situation is less critical as there will be a further opportunity to get onto the slow tracks just south of East Croydon station – although again on the level so not ideal. For southbound trains not going to the Oxted line (in practice the East Grinstead trains) that call at Purley there is a further opportunity to cross to the slow platforms at Purley just north of that station. If the train is not stopping at Purley then there is no reason why it shouldn’t stay on the fast tracks at East Croydon.
The missing Down Fast Victoria to Down Slow grade separation
As suggested above there is one pathway that does not have a fully grade separated route. That is from the Down Fast Victoria to Down Slow at East Croydon. Although provision has been made for an Up Slow to Up Fast Victoria Spur there has been no provision in the opposite direction. This is presumably because of lack of space.
Unfortunately, there the only routing that appears possible to enable fast trains from Victoria to reach the slow platforms at East Croydon is to cross the down fast Victoria trains to the slow lines at Selhurst. This is what happens now and it currently takes place south of Selhurst station.
Even more unfortunately, because there will be a new layout there, in future the crossing from the down Victoria Fast to the down Victoria Slow will have to happen north of Selhurst station. This aspect of the revised scheme is actually worse than before because this move is now proposed to be before reaching Selhurst. This means it will be blocked if there is a slow train calling at platform 1 (down slow at Selhurst). To make matters worse Selhurst Depot is accessed via platform 1 so it is to be hoped that when the railway is at its busiest there are no time-consuming driver changes at Selhurst platform 1 and there are no stock movements in or out of the depot from the Selhurst side. One also hopes that there are alternative arrangements made in future to resolve the issue of trains terminating short at Selhurst in times of disruption. Currently these terminate at Selhurst platform 1 before making their return journey back to London and obviously this is a time-consuming process. There is the option of sending them into the depot and out again on the other side to continue their journey back to Victoria by another route.
As with all weaknesses in track layout one has to consider how bad it is in the real world and what it takes to resolve it. In the case of “the Selhurst issue” there would not be that many fast trains affected. In the current timetable during the evening peak only 6tph call at Selhurst platform 1 and the same number of fast trains leave from Victoria and use the slow platforms on arrival at East Croydon. This would seem to indicate that this move on the flat would not be that big an issue at current levels of service. If it really were important there is probably a partial solution available at Selhurst by sacrificing the fast platforms in order to enable an extra through line to be built through the station, but even that would create problems as many early morning and late evening fast trains stop at Selhurst (some advertised, some not) in order to enable staff to get to and from work.
Here there and almost everywhere
With the fast trains sorted out, it remains for various grade separations to be made to connect the slow lines without affecting the fast lines. The issue of joining the fast lines to and from London Bridge with the slow lines at East Croydon also need to be addressed.
Two critical factors come into play when resolving the remaining issues. The first is that there is no need to consider the possibility of a fast train south of East Croydon becoming a slow train immediately north of East Croydon – it simply does not happen. The second is that, because the London Bridge lines are paired by direction, once you can get the London Bridge slow lines to the slow lines platforms at East Croydon then you can trivially get the fast lines connected by means of a crossover between the fast and the slow lines.
All together now
We can now put all the pieces together to reveal our understanding of what we think the current proposal is. In general it does look a lot better than before, though one wonders if TfL are happier because the more complicated trackwork may make it harder for them to push for an even more complicated layout for their enhanced proposals to allow 6tph London Overground to West Croydon.
Next time we will, hopefully, finally get further down the line and consider the line from East Croydon to South Croydon and South Croydon junction.
Many thanks to ngh for supplying an updated diagram with the latest changes. Thanks to him, Long Branch Mike and Graham Feakins for proof-reading and supplying additional information and ideas.
Postscript November 2016
Since writing this article the plans have been considerably enhanced yet again. Nothing official has come out of Network Rail but collating information from various sources enables us to suggest that the above revision is very close to Network Rail’s preferred option. Note that they are not yet at the stage of a final single option so, if the scheme is implemented, it may not be quite like this.
The biggest enhancement is to enable a full seven tracks between East Croydon station and Windmill Bridge. There is even more grade separation. A lot of this is enhancement is because all the analysis is tending to show it is even more cost-effective than originally believed to enhance the East Croydon scheme rather than attempt to mitigate problems elsewhere – notably, but not exclusively, at Stoats Nest Junction between Purley and Coulsdon.
Thanks once again to ngh for ferreting out the information and providing the updated diagram