Over the next year, people using the London Overground will start to see changes, as the line prepares for a 25% capacity upgrade.
One of the few advantages of running trains that are just 4 carriages long is that adding just one extra carriage can massively increase the capacity of the service — but that doesn’t mean it’s a simple upgrade.
Far from it.
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Not only are the stabling yards designed for 4-car trains, so are the platforms, the signals, the power supplies and even some of the track sections need working on.
Most of the works on the stations to lengthen them will start next year, but users of the Phase 2 extension to Clapham Junction may have noticed a large construction site just to the south of Surrey Quays station — and that is the first major works for the upgrade.
The Overground stabling facilities at New Cross Gate, which currently stable 21 four-car trains will be adjusted, but will only be able to house 13 of the new longer 5-car trains. Hence, the need for more stabling elsewhere.
An option to take over an existing site at Norwood would have avoided planning permission headaches, but as it is owned by Network Rail, would have left the Overground at the theoretical risk of later changes by the landlord. So, they took a bit of a risk and chose a plot of land that TfL already owned, and applied to build stabling yards there instead.
Hence, the Silwood Triangle.
This new site will become the home to another 10 trains and is conveniently close to the existing facility at New Cross Gate, where maintenance will continue to be carried out and trains washed.
Not the entire site is being taken over by the new tracks, as it sits in a slight depression, so tends to attract water from the local area which needs to be pumped away. Sometimes more water arrives than can be pumped away quickly, so rather than storing it in an underground sump, there is a local pond and mini-nature reserve.
There can’t be that many railway sites that need a life buoy next to them.
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Construction work should be completed in April 2014.
That coincidentally is also about the time when two of the existing 4-car trains will be sent up to Derby to be fitted with the 5th carriage for testing purposes. The two trains also need to be fitted with dual-voltage systems first so that they can get up to the Derby testing centre. Does mean that the two trains will be dual-voltage for future use as well, should such a need arise.
The loss of the two trains should affect the service, but a deal with Bombardier saw the number of trains needed as a buffer for maintenance work reduced so that passenger wont notice the two trains are elsewhere.
While that is going on, platforms at a number of stations will start to get lengthened in the first significantly visible sign that the upgrade is one its way.
Some platforms simply cannot be extended, such as Rotherhithe or Wapping, where selective door opening will see the 10 doors on the train reduce to 8. Surrey Quays was thought to be an eight-door station, but there is a bit of dead space at the southern end to extend the platform enough to add a bit more, so it will see 9 doors out of the 10 opening.
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Towards the end of next year, we should start to see the first passenger trains enter service with their new 5th carriage bolted on. Once that starts, they expect to convert a train per week, so about a year to roll out the entire fleet.
Ordinarily, having trains of either 4 or 5 carriages arriving means that the end carriage is little used as people wont wait on the platform where an occasional carriage might arrive — but as these are walk through trains, people can wait on the platforms at the 4th carriage stopping point, and then walk through to the fifth is it is there.
So we users should feel the effects of the longer trains much sooner than might otherwise be the case.
The longer trains will initially arrive on the East London Line section, with longer trains arriving on the Richmond/Clapham Junction to Stratford Line towards the end of 2015.
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Slightly off topic, but the machines for damping down gravel — never seen three of them hooked up together like that. It looked quite impressive, and nicely controlled by a remote radio link which is a good way of preventing white finger.
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Site access to Silwood was courtesy TfL and London Overground.