Cutting-edge heritage

8 min read

Stuart Nathan looks at the new train technologies being developed at Bombardier’s historic Litchurch Lane site

Visiting Bombardier’s Derby factory is a little bit like watching Doctor Who. Part of the genius of the venerable science-fiction programme is the recognition of the shock value of seeing something very familiar in an unfamiliar setting (it’s why the Tardis looks like a police box). Rounding a corner among Victorian brick factory sheds and suddenly seeing a brand-spanking-new London Underground train, above ground and a two-hour train journey away from its usual surroundings, has much the same effect.

Bombardier’s factory on Litchurch Lane, the last train manufacturing plant in the UK, is a mixture of heritage and cutting edge (again, a bit like Doctor Who). Soon to celebrate its 175th anniversary, the site was an important part of the Industrial Revolution and still plays a vital role in the life of Derby as one of Britain’s major engineering towns, with Rolls-Royce, Toyota and JCB among the major employers in and around the city. And although a worker from the old Midland Railway Carriage and Wagon Works would certainly recognise the site from the outside, those weathered brick exteriors hold the state-of-the-art equipment you’d expect from a modern facility currently hard at work on its new-generation train to take it well ahead into the 21st century.

The new Aventra train is designed to be able to operate in a variety of settings

Bombardier most recently made its way into the public consciousness with its failure to win the contract for new trains for the Thameslink line, which led its parent company to threaten to close Litchurch Lane. It is ironic (and perhaps typical of mainstream coverage of engineering and industry) that this made for much bigger headlines than the subsequent winning of a £188m contract for carriages for Southern Railways, which secured the factory’s immediate future. Today, Litchurch Lane is hard at work churning out trains for London’s Metropolitan and Victoria lines as well as those Southern carriages and a range of other train units.

Rail perhaps suffers from a perception problem compared with other large engineering/manufacturing industries in the transport segment. Aerospace is very obviously cutting-edge in terms of technology development, and automotive has a constant introduction of new models and pervasive advertising to keep them in the public eye. In trains, however, the development of technology isn’t always immediately obvious; we tend to think that a train is a train, and as long as it gets us where we want to go in the time the operator claims that it should, most of us really don’t think much about the development and the effort that goes into designing and building them, and unless their interiors are markedly different from what’s gone before, we don’t register when new models turn up on the tracks.

But that would be mistaken, as a walk around Litchurch Lane would prove. Developments and new technologies — both in the trains themselves and the techniques used to build and maintain them — abound, and improvement is continuous.

Despite its age, Litchurch Lane operates up-to-date manufacturing techniques

Bombardier’s president of rolling stock and services, Francis Paonessa, explained that the reason so much train technology is easy to miss is that it isn’t aimed directly at the train passenger; instead, it’s designed to meet the needs of train operators. ‘Modern trains don’t look very different from older ones, and the main difference you’d notice in many trains, such as our new Victoria line trains, is the extra information about the route and any problems along it that we can present to passengers,’ he said. But modern trains are more reliable, more energy efficient and more easily maintainable than their predecessors, as well as being more versatile in the ways that they can be operated.

‘Propulsion systems are a really good example of how product development works for us,’ Paonessa continued. ‘We’ve gone from old DC technology to much more modern AC technology, with components called IGBTs — integrated gate bipolar transistors — the switching gear that works as the train’s speed control — driving the propulsion system with full regenerative braking. We’ve also moved train control and management to an IP-based network, which gives us much more functionality on the train, from passenger counting to integrated CCTV. That’s also allowed us to move away from trains with guards to driver-only operation, using the CCTV on the platforms and inside the train so the driver can see what’s going on.’

Paonessa: Awaiting the specification of HS2 trains with interest

It has also led the train company into slightly more contentious areas — driverless Tube trains. Paonessa said: ‘On the Victoria line, the driver presses two buttons to launch the train and it drives itself: accelerates, drives up to the next platform, brakes and stops, then the driver opens and closes the doors and off it goes again. And as a passenger, you don’t know whether the driver is using the traction brake controller or whether it’s on automatic train operation.’

For the above-ground rail sector, Paonessa is seeing a definite trend in the UK away from diesel-electric units towards all-electric. ‘Currently only 40 per cent of the UK rail network is electrified, so we have quite a lot of diesel units,’ he said. ‘But we see the diesel fleet declining over the next 10 years, and in fact, with current emissions regulations, nobody has a compliant diesel unit. We’re concentrating more on batteries; the idea is that they charge up while the train is on electrified line, then act as the energy source themselves when the train is on non-electric line.’ Bombardier is currently running a trial of battery train technology with Network Rail, testing out two types of batteries — lithium-ion and liquid sodium-cooled — in a modified electric modular unit (EMU).

Currently, most of the development work at Litchurch Lane is focused around Bombardier’s new train ‘platform’, Aventra. Set to replace the older Electrostar trains, which will be familiar to many around the UK, Aventra is a system that can be configured for four different types of duty: metro; slow commute (local lines with lots of stops); medium commute (regional routes between larger centres, such as Edinburgh to Glasgow or routes in the Welsh Valleys); or fast commute (essentially the shorter intercity routes, such as London to Birmingham). It’s this train that — if Bombardier wins the contract— will ply London’s new Crossrail line from 2018.

Aventra, unlike the flat-fronted Electrostar, complies with new European regulations on train crashworthiness, which take effect from June 2017. ‘Visually, the trains have a pointier nose, which is actually a crumple zone in front of the driver, although it also has some aerodynamic aspects,’ said Paonessa. ‘That’ll have an effect on a lot of British operators, because we have a lot of flat-fronted trains in the UK, and operators also like trains with a gangway door at the front, because it makes it easier to join two units together. That’s a lot harder with a crash-cab, because of the sloped front.’

Aventra is described as an evolution of various Bombardier designs, intended to meet operator requirements well into the future. ‘The development process has been very different from contract work because with that you just have to meet the criteria that the contract stipulates,’ said Mark Ellis, head of engineering for rolling stock and services. ‘With Aventra, we started by going out to all the stakeholders and finding out what they needed. Once we had established that there were these four market sectors we could address, we set targets to make the train more reliable, more maintainable, cheaper, faster to market, and more energy efficient. The challenge was to see how well we had performed towards those targets in other projects right across the Bombardier Transportation business, and look at what technologies we could perpetuate in a new design concept and where we would have to develop something entirely new.’

’Lighter trains means savings in track access, and also, because they take less energy to accelerate, it gives you a very considerable boost to energy efficiency

Mark Ellis, head of engineering for rolling stock and services

Among the technologies retained in the new system is the Flexx Eco bogie, a compact propulsion unit incorporating lightweight electric motors and wheels that is used on Bombardier’s current Voyager and Meridian trains. This is much lighter than the bogie on Electrostar trains — a very important consideration for train operators, as mass is the deciding factor for track access — the fee they pay to get their trains onto the rail network. ‘Lighter trains means savings in track access, and also, because they take less energy to accelerate, it gives you a very considerable boost to energy efficiency,’ Ellis explained.

Once this had been established, the next task was to decide which components would be common to the whole Aventra range — ‘the bits that you don’t want to change, no matter which sort of service the train is operating,’ Ellis said. The team then decided what would be needed for each of the four main variants to produce a ‘sector core’ model. ‘Everything else was an option that operators could choose, similar to how you pick the options when you buy a new car.’

Modular building techniques minimise the number of workers needed inside the train when it comes to fitting out

On the new equipment side, Aventra incorporates improvements to Bombardier’s diagnostics and prognostics systems. Known as HUMS (health usage monitoring system), this is intended to spot problems before they occur. This system stretches from on board the train to trackside and to the maintenance depot. For example, the current curves for door motors are all stored on the train and compared against a standard profile. If the curve starts to deviate from the profile, an algorithm within HUMS will spot this and characterise the problem, determining whether the door is simply sticking or if
the motor might be close to going out of tolerance. If this is the case, Ellis said, it will alert the work ordering system and ensure that a new motor is delivered to the appropriate depot with an order for it to be replaced within 12 days, before the door problem results in the carriage going out of service.

Overall, Ellis agreed, the train industry is responding to many of the same challenges as the automotive sector in the same way: meeting energy challenges by lightweighting, and thereby using smaller, lighter engines to achieve the same, or higher, speeds as older models. ‘We switched from steel to aluminium some time ago, and we use polymers and composites extensively for interiors; we’d consider them for exterior panels as well,’ he said. ‘And the Flexx Eco bogie uses considerably smaller motors than the older models, as well as having the components in the same place rather than spread through the car.’

But speed isn’t everything. Paonessa noted that Bombardier is building the fastest trains in the world: the Zefiro 380 in China, which has been tested at 420km/hr, and the fastest in Europe, the Zefiro V300, which it is building in Italy as a joint venture with AnsalsoBreda; despite its name, the V300 runs at 360km/hr.

‘The problem with high-speed trains is that you need a lot of space to run them, and not too many curves. In the UK, there are very significant constraints of space, time and distance, so you have to reach a balance between how far you are travelling, the constraints of the infrastructure, and the basic constraint of the size and geographical features of the country and how many people there are in it, and their distribution,’ he said. ‘It’s just not physically possible to push the boundaries of speed, and when you have to accelerate and decelerate the train, the top speed quite quickly drops down the list of priorities. It’ll be very interesting,’ he concluded, ‘to see what the HS2 team comes up with for its final specification.’

Off the line: building trains the Bombardier way

Bombardier’s philosophy for train building is quite different from those of its competitors. Rather than building the whole shell of a car and fitting it out, assembly is modular as far as possible, with the completed modules bolted together to form as complete a unit as possible. This prevents overcrowding on the critical assembly path and maximises the time available for component testing at the point where faulty components are easiest to replace.

Wiring harnesses, for example, are assembled directly onto CAD diagrams blown up to 1:1 scale before being transferred into their aluminium trays — which are also bent, drilled and assembled on-site from sheet metal — and flashed at high voltage before being attached to the floor of the car. Side panels are assembled complete with doors and door motors, and the electrical cabinets for the drivers’ cabs for the end of the cars wired up and fully tested before being bolted into position.

Once the floor, ends, side panels and roofs of the cars are bolted together on an elevated platform, the bogies are jacked up and attached to the bottom before the car is lowered onto rails for testing at the site’s test track. The sight of a brand-spanking-new Tube carriage hoisted 6ft in the air, with line maps all in place and the colours of the moquette seating glowing brightly, is perhaps the most surreal vision of Litchurch Lane.