HomeRail NewsFurther development of 4LM
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While the new control room at Hammersmith is just commencing the first stages of testing, the new Thales SelTrac communications-based train control (CBTC) system has already been undergoing full dynamic testing for some time – 100 miles away.

Rail Engineer reported on the first stage of testing early last year (issue 138, April 2016). At that stage, a Bombardier S Stock train, fitted out with aerials, sensors and electronics, was running up and down the track at RIDC Melton (the Rail Innovation and Development Centre at Old Dalby) testing the basics of the system.

The installation was very much ‘prototype’ – lots of duct tape and electronics balanced on trestle tables – but the train stopped where it was meant to, opened and closed its doors on command, and obeyed speed instructions.

Testing continues

Eighteen months later, those tests are still going on. Now, however, the train looks completely standard – all the aerials and wires have been hidden away and the electronics are tucked into a cabinet in the driver’s cab. The software, too, is the latest version, just going through a series of checks before it is rolled out at Hammersmith.

There are still a few wrinkles to iron out. The driver’s display, a combination speedometer, speed limit indicator and door status warning, has yet to be integrated into the control desk – for test purposes it is bolted to a handy post about one metre away.

Inside the train, a few extra cables are still around, but these are just for the test equipment that is checking the train’s performance.

And, of course, there is the inevitable blue ‘safety’ string across the doors, so that test personnel don’t fall out as the train opens its doors at virtual stations.

Externally, the train looks as it did before. There are a couple of antennas mounted high up, and natty little sleet deflectors on the covers for the OPO (one person operation) receivers, mounted under the buffers. These relay the CCTV images from the platform to the drivers’ desks, so they can check when it is safe to close the doors and launch the train. The receivers were being affected by ice build-up in the open-air sections of the line in winter – and it took a test trip to Norway to fine-tune the answer!

The trains are being returned, one at a time, to the Bombardier works in Derby to be retrofitted with all of the kit. It’s a very invasive process, as most of the train’s interior has to come out so that the cables can be installed.

Only a few of the production trains are being tested at Old Dalby, and that’s to develop the system and check the interfaces between the trains and the track. Every other train will undergo static and dynamic testing at Bombardier’s Derby site and back in London on its return.

4LM programme

London Underground’s acting head of the 4LM programme, Chris Hobden, explained the programme.

The new signalling system will be introduced in 15 stages, termed signal migration areas (SMAs), numbered 0.5 to 14. The original first migration, from the Hammersmith terminus to Paddington, has been cut in half to make the very first implementation simpler and allow maintenance and operations staff, as well as train operators, to get used to the new equipment and operating methods. This is why the first SMA, which goes to Latimer Road, has rather strangely been termed 0.5.

The programme is not without its challenges. SMA 6 and 7, from Stepney Green to Upminster, runs alongside a ]Network Rail line fitted with 25kV AC overhead line equipment (OLE), so the new equipment has to be proofed against electro-magnetic interference.

The District line tracks to Wimbledon and Richmond (SMA 10 and 12) will be an ‘overlay’ system, whereby the Network Rail signals will remain in place and the Thales SelTrac will take its information from them.

In contrast, the Metropolitan lines between Harrow-on-the-Hill and Amersham (SMA 9 and 13) will be an ‘underlay’ system – the Thales CBTC system provided by Thales to London Underground will control new lineside signals on this part of London Underground’s infrastructure that are compliant with Network Rail standards for Chiltern Services.

The implementation of the new signalling is very much a cooperative effort. London Underground is providing the basic infrastructure, the control room, equipment rooms, cable routes and power supplies. Thales is providing the signalling system and Bombardier is upgrading the passenger trains.

To complement the programme, Track Partnership (LU and Balfour Beatty) is making track modifications and the traction power system has been upgraded to 750V DC with regeneration up to 840V.

As the new S Stock fleet of 192 trains is larger than those it replaces, additional sidings have been built to accommodate them.

Onward to the future

Jeremy Hooper is Thales’ delivery director, and he gave more detail on the programme.

The core of the new system, represented by SMA 0.5 to 7, is effectively one design. As mentioned above, this will be modified to provide the underlay and overlay systems that will run alongside Network Rail in other areas.

As well as the 192 Bombardier S Stock trains, all of the London Underground fleet of engineering trains which work on the Sub-Surface Railway will also need to be fitted with the new in-cab signalling system. Thales has done the design, developed the kit that London Underground is fitting in its own workshops, and is assisting with the first-of-type testing.

Signalling equipment rooms (SERs) are now in place at Hammersmith, Paddington and Edgware Road, the first of 46 such facilities that are being built across London, including one under Sainsbury’s at High Street, Kensington. Here, access is so restricted that materials have to go in and out by engineering train, run within the passenger timetable, and only on a Thursday!

Data is being gathered on powered-up signalling equipment and the Hammersmith Control Centre is under test with night-time test train running now taking place as far as Edgware Road.

The whole development programme has very much been a collaborative effort between London Underground, Thales (signalling supplier), Bombardier (train manufacturer), Network Rail (some running line and owner of RIDC Melton), Serco (operator of RIDC Melton) and even Crossrail (interference assessment at Paddington).

The main London Underground and Thales teams are co-located at Stratford. In addition, a team from LU spent some time in Canada, working with Thales engineers to develop the functionality of the software.

The development team has been pleasantly surprised by the performance of Bombardier’s trains. When under automatic control, stopping distances and locations are very consistent and the train is very reactive, even at low speeds. This is important when trains have to stop at the same place on a platform every time, particularly since the required tolerance can be as low as ± 0.5 metres.

The use of the test track at Old Dalby has been a blessing too, making system development much easier than those for the Northern and Jubilee lines, which didn’t have that facility.

By the time that SMA1 to Paddington goes into passenger service, 53 of the 133 train strong S7 (seven-car S Stock) fleet will have been fitted with the new in-cab signalling. All 58 of the S8s, and some of the engineering vehicles, will be fitted out before services start on SMA2 (Edgware Road to Euston Square). The entire fleet will be converted for SMA3 (King’s Cross to Aldgate, Monument and Stepney Green).

The current plan, as revealed by David Hughes, TfL’s director of strategy and network development, is for SMA1 to be in service by the summer, and SMA2 by October.

The true benefits of 4LM will become visible once SMA6 is complete (Mile End to Becontree). The timetable changes will be possible, taking the current 28 trains per hour (tph) in the central section to 30tph at peak times (Timetable ‘A’ – December 2021) and then on to 32tph by May 2022 (Timetable ‘B’). Further enhancements, expanding the 90-minute high-density peak period to three hours and enhancing off-peak services, will continue until December 2023.

It’s all going well. As David Hughes commented last October: “The 4LM Programme is expected to deliver benefits earlier then planned at a cost £144m less than planned.” And that has to be good news.

This article was written by Nigel Wordsworth.

Read more: The other Northern Powerhouse – behind the scenes at Amey Rail North




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