Seeing London Underground trains run through the Leicestershire countryside is nothing new. The Old Dalby test track was leased by LU as far back as 2007, with Serco being contracted to operate and maintain it.

Four kilometres of the 7.5km-long Up line were fitted with 630/750V fourth-rail DC electrification, in preparation for testing Bombardier’s new S Stock trains, being manufactured 30 miles away in Derby. The twin voltages would allow for testing at both the existing and upgraded London Underground electrical supply levels.

The first new train entered service on the Metropolitan line in July 2010. Every subsequent train, and there will be 192 of them, has had to undergo a minimum of 500 kilometres of fault- free running at Old Dalby before LU will accept it. That’s 125 runs up and down the line for each train, or 96,000 kilometres of testing – not including any repeat testing if a fault has to be fixed and testing restarted.

Serco’s drivers have been busy.

Now, however, there is a new development. One of the test trains has been stopping on the line, opening its doors, closing them again, moving on a few hundred metres, and doing the same thing all over again. Strange….

So there was nothing for it but to drive over to Old Dalby to find out why.

Testing, testing…

On arrival, the first thing to notice was that the test track isn’t called Old Dalby any more. Instead, since the facility was acquired by Network Rail in December 2014, it is RIDC (Melton) – that’s the Rail Innovation and Development Centre and it is named after Melton Mowbray, 7.5 miles to the south-east. This is to both link it, and distinguish it, from RIDC Tuxford (formerly High Marnham) which Network Rail set up in May 2009.

Both facilities are used for railway vehicle testing, but Melton is particularly set up for testing trains while Tuxford is largely used for on-track machines, road-rail plant and infrastructure testing.

On the day that Rail Engineer visited RIDC Melton, one of the new Hitachi IEP trains departed for North Pole depot in London. It had been testing on the longer, 21km Down line which is electrified with the new Series 1 overhead catenary, replicating that being installed on the Great Western.

But parked next to the fence and the Old Dalby operations offices was the item of interest – a brand new S Stock train with zero in-service miles. It had completed its 500 fault-free kilometres of running, then been handed over to engineers from Thales to act as the test train for its new Seltrac signalling system for the Sub Surface Lines.

Grey boxes

The contract to completely replace the signalling system on the four London Underground lines that make up the Sub Surface Railway (Metropolitan, District, Circle and Hammersmith & City) had been awarded to Thales in July 2015. It is to be a CBTC (Communications Based Train Control) system with almost no lineside signals – they will only be retained in areas shared with other trains such as the Chiltern line, the Richmond branch, the Piccadilly line between Uxbridge and Rayners lane and the Wimbledon branch. Instead, the train talks to the control room and instructions to the driver appear on the train’s control desk.

Although the contract was only placed nine months ago, Thales was in a good position to make an early start. A similar system has already been introduced on the Jubilee and Northern lines and is now working well. So the first implementation of the new SSR system is, not surprisingly, quite similar to that on the Northern line. Some of the equipment is one generation newer, and the software has been modified to account for some of the differences between the complex SSR and the comparatively uncomplicated Northern line, but the similarities are there to see. The main difference is communications – Northern line trains ‘talk’ to the control centre using an inductive loop system while the new SSR system uses radio.

The similarities, however, were such that it gave the Thales engineering team the opportunity to make a quick start. Mobile office units were set up next to the Old Dalby car park, and filled with tall grey cabinets mysteriously labelled “SCS1”, “PDU Rack 2”, “COM Rack 3” and “VCC”.

DSC_0822 [online]

The latter is the Vehicle Control Centre, and it is the brains of the whole operation. Inside the cabinet are three large rack-mounted computers, all basically doing the same thing and controlling part of the network. The 4LM (4 Lines Modernisation) project will have 14 VCCs, overseen by the System Management Centre (SMC) which acts as the operator interface and controls the service according to LU’s timetable. Two of the three computers must agree at all times, otherwise the output will not go the rest of the system and the trains will come to a stop.

The other cabinets control the systems at the various virtual stations that have been set up along the test route (SCS – Station Controller Substation), communications and uninterruptable power supplies for the whole system.

Most of these cabinets are production items and will appear on the actual SSR installation, although the SCS ones will be located at stations and not at the control centre.

The control room itself, however, was nothing like the final version. A row of desktop computers on office desks will be replaced with a bespoke, air-conditioned room with banks of video screens when it is installed in London.

On board

Having looked behind the scenes, it was now time to board the train itself.

First impressions were just how enormous the train is. It was one of the shorter ones, seven cars and 385 feet (117 metres) long, but when completely empty, and with wide gangways that allow views along the length of the train, it looked huge. Protective matting covered the floor and the only sign of life was at one table which had been erected just behind one cab, where a Thales engineer kept watch over the VOBC (Vehicle On-Board Controller) sitting next to him. Eventually, this will be built in to the space that awaits it in the cab itself.

Various cables sprouted from the VOBC and were taped to the interior of the train, some going to the cab and others making their way outside to bits of kit under the floor. Doors were closed off using thin, red and white striped ‘safety’ tape from which hung signs reading “Warning – Doors May Open At Any Time”.

After the doors had been closed, the train could make its way slowly out onto the test track. Once there, confirmed by radio and the new cab controls, the Serco driver pressed two buttons to engage the ATO (Automatic Train Operation) and we were off.

Thales project director Andy Bell explained that, while ATO formed part of the specification, with the driver opening the doors once the train was at a standstill, closing them again and launching the train, UTO (Unattended Train Operation) did not. So while the train would drive itself to the next station, and stop at a precise point on the platform, there was no plan to run without a driver who would still be responsible for passenger safety by controlling the doors and being able to drive the train manually if necessary.

Rolling along

It all worked perfectly. The train headed off down the test track, reaching its current maximum speed of 35km/h (this will shortly be updated to 80 kph as testing progresses), whereupon it soon slowed and stopped at the first virtual station.

On this run, the driver didn’t open the doors, but he waited until signalled by the control room whereupon he launched the train off to the next stop.

Several stops later, speed decreased dramatically to only 10km/h. Had something gone wrong? No, it was just a section of jointed track, replicating the variety to be found in London’ tunnels and sidings such as Hammersmith depot.

Once the train reached the end of the line (or at least of the four-rail electrification), the driver isolated his controls and walked back the 385 feet to the other cab where he turned the master control switch to select ATO mode, talked to control on his radio, pressed two buttons, and we were off again.

It was all very painless and without any sort of drama. And that’s the point. Thales, Bombardier and London Underground are quietly proving the system, in the heart of Leicestershire, before any disruption takes place on the underground network.

What next?

Stuart Harvey of LU went through the rollout of the programme. Two weeks after this visit, a series of software upgrades were expected for both the on-train VOBC and the control centre VCCs. These would be developments derived from the results of the testing at Old Dalby (sorry – RIDC Melton) and would make the programming a little more specific for the SSR.

DSC_0796 [online]

Then, once testing is complete, will come the task of installing the new equipment along 314km of track and on 102 stations, making up over 40 per cent of the total Tube network. This includes several complex flat junctions, as well as some lines which are shared with Network Rail.

Substantial track alterations will be needed, to be carried out by Track Partnership, LU’s collaboration with Balfour Beatty. The on-track transponders, which the train uses to work out where it is, have to be fitted along the trackbed – every 25 metres in most areas although the system supports 50 and 75 metre spacings where safety distances are less of a concern. Radio transmitters need to be installed so the train’s radios work in the tunnels.

As the whole purpose of this exercise is to run more trains, more power will also be needed. Supplies will be increased to 750V DC and more feeder stations will be installed.

The trains themselves, the last of which will be delivered this summer, will be returned to Bombardier so that the signalling equipment can be installed. This includes the VOBC fitted in the cab, radio aerials and transmitters, transponder interrogator units under the floor which have Radio Frequency Identification (RFID) antennae for reading the transponders which provide absolute positioning information, and in the order of 2,000 wiring changes.

Meantime Thales will be fitting out the main control room which will run the whole network, at the same time installing the relevant equipment at stations and depots.

All of the engineering trains need converting to run on the Sub Surface Lines. This job will be made easier by many of them already being able to run on the Northern line with its similar Thales Seltrac system, although the rail adhesion trains are specific to the SSR network so they will need to be upgraded.

Timetable

The first 53 S Stock trains are due to be completed by February 2018, ramping up to the full fleet by September.

Implementation will be split into 14 ‘migration areas’ or sections of the network. Some of the early ones will be where the most trains run – the northern part of the circle line – and trains will start to run here under ATO control by the middle of 2019. Then further sections will be brought into use until the full network is on ATO by the end of 2020.

Once implementation is complete, then the capacity enhancements will come in. Running under ATO, trains can use their full 100km/h design speed (without ATO they are limited to 72km/h).

At slow speeds, trains can be as little as 50 metres apart, higher speeds will necessitate a larger safety distance. The calculations are still to be completed for these speeds. Thales Safety Distance calculations are similar to an overlap calculation and consider worst case conditions in a similar manner.

Allowing trains to run more closely together will allow 32 trains per hour in the busiest section (it is 24 per hour today). That’s the Circle line running almost as many trains in 2020 as the Victoria line does today. And anyone who has seen a Victoria line train enter the platform before the previous one has cleared it will know how impressive that service is.

London commuters are looking forward to that day.

Thanks to London Underground project manager Deidre McGinn and to Thales integration verification validation and qualification manager Richard Kirby for their help with the technical details of this article.