Orange South London

The think tank Centre for London published a report on rail in South London today (14th January 2016), entitled "Turning South London Orange". This is my thoughts on the report.

South London

The report outlines the problems facing rail in South London (specifically South Central, not South East or South West) and proposes some solutions. It tackles these in the context of London Overground, the "Orange" network of tube maps. As well as covering the transport side, the report adds background and numbers on the project growth and potential additional growth that could be unlocked by an investment. It recommends TfL (Transport for London) takes over the existing services within London (ie. conversion to London Overground), and it gives consideration to a new regional transport body covering London, Kent, Surrey and Sussex to balance the needs of London with those beyond.

The rest of the article will focus mainly on the proposed investment ideas. Firstly, there is a set of ideas that few would disagree with:

• Enhanced signalling, with greater automation
• Better trains, with wider doors, better braking and acceleration
• More effective station stops, using staff and technology
• More turnbacks, to provide for a high frequency service

Beyond the basics, three more specific investment ideas are discussed, starting on page 44.

A new South London Line

This proposal is to increase the frequency of the line from Victoria to Lewisham and provide more stations.

The current Overground service runs from Clapham Junction to Canada Water and beyond at 4tph (trains per hour). The report propose increasing this to 6tph, and adding an additional Victoria to Lewisham service, also at 6tph. To make this work, the report suggests additional platforms at Battersea (near the power station), Wandsworth Road, Clapham High Street, Clapham East, Brixton and Brockley.

Thameslink, Herne Hill, and a resolution for Brixton

This proposal is for a new tunnel running from the Wandsworth Road area to the Dulwich area. This would be a fast line tunnel, taking those services from Kent that run non-stop from Bromley South to Victoria.

By building a new fast line tunnel, the flat junctions at Herne Hill and Brixton are relieved. This would provide enough space for the proposed Victoria to Lewisham service, plus an enhanced local service from Victoria to Bromley South. In addition, the extra capacity would allow platforms to be built at Brixton, not on the high viaduct, but on the lower level one on the north side.

The report discusses the flat junction at Tulse Hill but does not propose anything specific. It does indirectly mention a flyover, which is likely to be necessary to enhance frequencies through there.

Streatham ‘Virtual Tube’

The concept here is to build a new tunnel from Streatham to Streatham Hill with a rebuilt four platform hub station at Streatham. This would allow services from Streatham Common to run via Streatham and Streatham Hill to Balham and Victoria. A flyover junction is discussed to ensure the service to Streatham Common would be reliable.

The report claims a frequency of a train every 2 to 3 minutes at Streatham with this investment. I suspect the report authors mean 12tph to Victoria (one every 5 minutes) and 12tph to Tulse Hill, split between London Bridge or Thameslink (one every 10 minutes to each).

My thoughts

These proposals are a good starting point for discussion.

The proposal for a fast line tunnel under Herne Hill and Brixton seems pretty sound to me. The goal is correct - to separate the long distance services from Kent to Victoria from the metro services. The current timetable from Bromley South to Victoria shows 9tph of fast services and 4tph of slow service.

A fast line tunnel would easily have capacity for the 9tph of fast services, leaving free space on the existing surface lines for additional slows services. However, the devil is in the detail. To work effectively, the fast line tunnel must start far enough south to free up the additional capacity. Otherwise, there will still be conflicts between Bromley South and West Dulwich. As such, it may be necessary to run the new tunnel as far south as Kent House, which is quite a lot further.

Another question with the plan is that 9tph is relatively low usage for an expensive new tunnel. Of course, with increasing demand, this 9tph might be increased once the new tunnel opened. But it seems unlikely that it would reach 20tph. As such, it is fair to look to see if anything else could use the tunnel, potentially increase the value of the investment.

One possibility would be a second southern portal somewhere north of Norwood Junction. This would allow some services from there to run non-stop to Victoria. This would be of most use to the services from Caterham and East Grinstead, which deserve fast services but are in danger of being crowded out. A tunnel providing 12tph non-stop from Bromley South to Victoria and 8tph non-stop from Norwood Junction could be a powerful combination.

The plans for platforms at Brixton make sense with the additional capacity of the tunnel. However, since the tunnel would remove all fast services, it would seem that the high level viaduct in Brixton would be unused under the proposed plan. This possibility offers another way to provide platforms at Brixton.

If the low level viaduct was reduced from 2 tracks to 1 track, an eastbound platform could be added on the viaduct in the space saved. Similarly, the high level viaduct could be reduced from 2 tracks to 1 track with the space saved used for the westbound platform. Together, this would provide a flyover junction at Brixton for the metro services of the three routes - Victoria to Lewisham, Clapham Junction to Canada Water and Victoria to Bromley South (via Herne Hill) - which would increase reliability.

The second major investment discussed is the Streatham 'virtual tube'.

A tunnel from Streatham to Streatham Hill has long been a sensible thing to consider. Access to Streatham is perhaps the key piece in South London's jigsaw, and tackling it a necessity of any scheme.

My problem with the concept outlined in the report is that it takes services from Streatham Common, via two additional stations, something guaranteed to extend journey times. A more likely, and cheaper plan, would be to serve Streatham and not Streatham Hill.

Regular readers will know that I am championing the Swirl-Max plan for Crossrail 2, which has a branch from Clapham Junction to Streatham via Balham. This includes a tunnelled curve from Balham to Streatham, very similar to that proposed in this report.

So, could the Swirl-Max tunnel be extended to serve more of South London? The answer is yes, but it relies on an additional tunnel from Clapham Junction to Central London, ie. Crossrail 3. This is because at least 20tph of Crossrail 2 are needed by Wimbledon, leaving just 10tph for Streatham. While 10tph is enough for Streatham alone, it is not a high enough frequency to cope with the demands of serving the broader South London area directly.

In brief, here is what would have to happen to convert the Streatham branch of Swirl-Max into Crossrail 3.

1. Build a new tunnel from the start of the Streatham branch to Clapham Junction
2. Build two new tunnelled platforms at Clapham Junction
3. Build a new tunnel from Clapham Junction to somewhere in Central London, such as Blackfriars via Vauxhall and Charing Cross, or Baker Street via Victoria
4. Build a new connection from the surface at Streatham Hill to the tunnel under Balham
5. Run 10tph from Crossrail 3 to Crystal Palace, and 10tph to West Croydon via Selhurst, plus the original Swirl-Max 10tph to Wimbledon via Haydons Road.

As can be seen, the Swirl-Max Streatham branch can very effectively be the base building block of Crossrail 3. (And in an ideal world, points 1 and 2 would be done as part of Crossrail 2.)

Finally, I have to note the elephant in the room when looking at the Centre for London report.

The report proposes doubling the usage of South London's rail network. But this network ends at London Bridge and Victoria. Only the Thameslink line runs through Central London, and only a maximum of 8tph is available there. But how many of those new passengers will have a job right by the terminus station?

As such, it is my opinion that the plan in the report would dramatically increase the pressure on the tube in Central London, with only Crossrail 2 providing any relief. While the report seeks to explore options without tunnelling in zone 1, it seems to me that there is simply so much demand as to require an additional Crossrail.

Which brings us full circle to Swirl-Max and the building blocks it provides for Crossrail 3!

Summary

The new report into rail in South London makes a good contribution to the debate, particularly on the governance and growth sides. On the transport investments, there is no doubt that if built as proposed, they would be a step up for South London. However, I fear they would also create major overloading of the tube, particularly from Victoria. As such, I don't see how rail in South London can be considered without at least one eye on a future Crossrail, with the Swirl-Max plan plan for Crossrail 2 offering a great starting point.