The Anonymous Widower

Thoughts On The Sutton Loop Line

The Sutton Loop Line is a bit of a problem.

  • It runs two trains per hour (tph) in both directions.
  • Trains are eight-cars.
  • It is not the most heavily-used of lines.

It is deeply political and difficult to make any changes.

Network Rail’s original plan is described under Political Developments in the Thameslink entry in Wikipedia. This is said.

Network Rail had planned to terminate Sutton Loop Thameslink trains at Blackfriars station, rather than have them continue through central London as at present. This would increase the capacity of the central core as the Sutton Loop could only accommodate shorter trains. This upset many residents in South London and their local politicians, who saw it as a reduction in services rather than an improvement. In response to pressure, government has ordered Network Rail to reverse the decision.

Was this design by those, who don’t understand the complexity of designing and running a train service?

On the other hand, the line has some strengths.

  • It is a double-track railway.
  • It is fully-electrified using 750 VDC third-rail.
  • Stations have long platforms.
  • There seems to be quite a bit of housing and other development.

But in some ways,  the line’s biggest strength, is the wide margins at both sides of the tracks.

This section between Hackbridge and Carshalton stations is not untypical.

Adding extra platforms or complete stations would not be difficult.

What solutions are available to improve train services on the Sutton Loop Line, for both passengers and train operators?

Splitting And Joining Trains

In Has Thameslink Got The Wrong Length Of Train?, I proposed the following.

  • Using twelve- and six-car trains on Thameslink.
  • Allowing two six-car trains to work as a twelve-car unit.
  • Trains would be able to join and split automatically, as Hitachi’s Class 395 trains are able to do.

I also proposed the following method of operation for the Sutton Loop Line.

The Sutton Loop Line could be run by using six-car trains that split and join in the area of Streatham station.

This map from carto.metro.free.fr shows the track layout at Streatham, at the start of the loop.

Note.

  1. Streatham South Junction is the gateway to the Sutton Loop, with the tracks to the West going via Tooting station and those to the South via Mitcham Eastfields station.
  2. There is a lot of spare land in this area.
  3. Transport for London keep talking about creating an interchange at this point.

I think, if and when the interchange is built, it could be designed, so that it increased traffic around the Sutton Loop Line.

  • Two six-car trains running as a twelve-car could split at the interchange.
  • One train would go round the loop clockwise and the other anti-clockwise.
  • The trains would rejoin together at the interchange.

The same procedure could be done at Streatham, without creating the interchange, but it would block the station, if trains got delayed on the loop.

Currently, two trains per hour (tph) are proposed to run in both directions on the Sutton Loop Line.

This requires four eight-car trains and four paths through the central core.

If four six-car trains were to be used, running in pairs splitting at Streatham station or a new Streatham Common interchange, there would still be two tph in both directions round the Sutton Loop, but only two paths would be needed in the central core.

Travellers to and from stations on the loop would see six-car, rather than the current eight-car.

If the number of six-car trains were to be doubled and four paths used in the central core, the Sutton Loop Line would see four tph in both directions.

It sounds complicated but it would work and it has the following advantages.

  • Train frequency could be increased as required.
  • Paths are released in the central core.
  • Twelve-car trains would go through the central core, where the capacity is needed.

The service would need a few more drivers and other staff.

Loop Only Services To A New Streatham Common Interchange

If a new interchange station is built at Streatham Common, then extra services could easily be run round the loop.

  • Thameslink services could be reduced to perhaps one tph in each direction.
  • These would be augmented by perhaps a four tph shuttle around the loop starting and finishing at Streatham Common.
  • The shuttle trains could be any suitable unit, but surely a four-car would suffice.

I suspect that this wouldn’t work, as it would upset the natives.

The German Solution

I can’t help feeling that the Germans and especially those in Karlsruhe would look at the Sutton Loop Line and because there are both trams and trains, in the area, they would come up with a solution based on trains and tram-trains.

As fsr as I know, no-one has ever built a third-rail-powered tram-train!

But I don’t think that a tram-train powered by third-rail electrification, when running as a train is an impossibility. I lay out my ideas in The Third-Rail Tram-Train.

Safety

As to safety, look at this picture taken at Mitcham Junction station.

Note how the third electrified rails are in the middle away from the platforms. This is standard practice with this form of electrification.

So if it is deemed to be safe for trains now, it will surely be safe for third-rail train-trams.

When running as trams, the tram-trains will use 750 VDC overhead electrification.

Changing Networks

Tram-trains will need to change between the tram and rail networks.

This map from carto.metro.free.fr shows the track layout at Mitcham Junction station.

Note.

  1. Wimbledon is to the West and Croydon is to the East.
  2. With the addition of some extra tracks, it should be possible for tram-trains to pass between the networks.
  3. As trams can take tight curves, a chord could allow Westbound tram-trains from Croydon to turn South to Sutton.
  4. Tram-trains will probably change networks using a couple of ininutes of battery power.

I doubt any of the engineering will be too difficult.

Adding The Sutton Loop Line To Tramlink Using Tram-Trains

Tram-trains would take the following route.

  • Arrive from Croydon at Mitcham Junction, where they would turn South onto the Sutton Loop Line.
  • Pass through Hackbridge and Carshalton stations.
  • Call in Sutton station for interchange with trams and National Rail.
  • Continue to Wimbledon station calling in Platform 9 for interchange with trams in Platform 10 and 10b and National Rail.
  • Pass through Hatdons Road and Tooting.
  • Take new chord to cross to the other leg of the Sutton Loop Line.
  • Pass through Itcham Eastfields station.
  • Rejoin the tram route at Micham Junction station.

Tram-trains could also travel in the reverse direction.

Trams And Tram-Trains At Wimbledon

This map from carto.metro.free.fr shows the track and platform layout at Wimbledon station.

Note.

  1. Currently, Thameslink services on the Sutton Loop Line use Platform 9 in both directions.
  2. Hayons Road station is to the North-East and |Wimbledon Chase station is to the South.
  3. Tram-trains on the Sutton Loop Line would do the same.
  4. Platform 9 probably defines the capacity of the Sutton Loop Line.

Access to the trams in Platforms 10 and 10b, is just a walk across the platform.

The picture was taken from a Thameslink train.

There might even be space for another tram platform, that can be accessed from the Haydons Road direction.

Trams And Tram-Trains At Sutton

This map from carto.metro.free.fr shows the track and platform layout at Sutton station.

Note.

  1. The Sutton Loop Line is the Northernmost pair of tracks.
  2. Carshalton station is to the East and West Sutton station is to the West.
  3. It could be possible for tram-trains to by-pass Sutton station and run on the streets of Sutton.

This picture shows Sutton High Street.

Is it going to be easy to bring the planned tram extension from Wimbledon to Sutton?

Dual Platform Issues

Platforms at the stations on the Sutton Loop Line are long and are certainly capable of taking eight-car trains.

But are they long enough to have a lower section of platform, so that tram-trains can have step-free access?

This is one of the problems, that should be solved in the tram-train trial in Sheffield.

The Split At Streatham Common

This Google Map shows, where the two routes of the Sutton Loop Line meet near Streatham Common station.

This picture shows a train going towards Mitcham, from one having passed through Tooting station.

I don’t think it would be the most difficult engineering project to create a chord, that would allow tram-trains to go directly between Tooting and Mitcham Eastfields stations.

A Possible Service

As I said earlier, Platform 9 at Wimbledon station. is probably the limiting factor on services round the Sutton Loop Line.

Thameslink is planning two tph in both directions.

I suspect that this could be supplemented by two tph services run by tram-trains, if a signalling solution can be implemented to allow four tph in each direction, through the platform.

Conclusion

There are several ways to improve the Sutton Loop Line.

 

 

 

March 14, 2018 - Posted by | Transport | , , , , ,

1 Comment »

  1. I think the Sutton Loop should be operated as an extension of the Victoria Line. I’d like to know what you think.

    Comment by Peter Dowden | April 14, 2018 | Reply


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