Return to Archive -by date - by topic.

INFORMED SOURCES April 2003

Turbostar Evo' takes up the challenge

Britain 's best selling EMU gets an upgrade

Turbostar is one of those designs that have no exceptional features, but do everything adequately. It is the Boeing 737 of the rails, equally at home on commuter, inter-urban and even secondary inter-city duties.

Captain Deltic complained that it was a bit short in the power department, with a girly converted bus engine which suffered initially when subject to a good traction thrashing. And while Hull Trains Class 170s don't hang about on the East Coast Main Line, the 422hp 11 litre engine's lack of puff is exposed when up against the 750 hp of InterCity units powered by the mighty Cummins QSK 19.

But, as I was told in an exclusive interview with Bombardier's Director of Bids Robert Zappa, Turbostar is about to evolve into a pocket rocket. And, no, that does not mean squeezing a big Cummins under the floor.

Floors and doors

With the Trans-Pennine Express franchise in mind, Bombardier modelled the total journey times of Turbostar and its Class 222 Meridian over the route. This study came up with some interesting observations when it came to floor height and door configuration.

With the higher floor of the Class 222, compared with the Class 170, needed to accommodate the 19 litre Cummins QSK19, an intermediate step up from the platform is required. Negotiating this slows boarding and alighting. Meridian 's end doors further exacerbated the delay compared with the 1/3 2/3 arrangement of the Class 170. The net effect was to erode some of the advantage of the more powerful engine.

So, the obvious decision was to retain the Class 170 bodyshell. Apart from using a proven product, the 20m vehicle ensures the wide route availability needed to maximise residual value.

That said, Bombardier still needed more performance for inter-urban running, if the 100mile/h capability was to be exploited. The key is acceleration to get up to line speed as quickly as possible and acceleration is determined by power

Clearly, a 750hp engine was incompatible with the floor height, but Cummins' 14 litre N14, would fit. In the Turbostar Evo it will have a maximum output of 513hp at 1900 rev/min.

Auxiliary grunt

That is still well short of the QSK19. But remember that the engine in a DMU has to power those hungry auxiliary systems such as air conditioning.

Thus the Turbostar Evo will have a separate diesel generator – also Cummins powered - to supply the auxiliaries. This means that all the horses from the main engine go to the wheels.

With the generator rated at 100kW, Turbostar Evo's total installed power is 650hp versus Meridian 's 750hp.

Now add a further factor - electric drive in place of the hydraulic transmission of the Class 170. Once again, Bombardier is using proven components by mounting the Evo on Electrostar bogies with two powered axles per car.

Unlike the Meridian , with its body mounted traction motors driving through cardan shafts, the Electrostar three phase traction motors are bogie mounted, which helps underfloor layout. Bombardier's traction company in Sweden will add the alternator and control package. Electric traction should provide better control of adhesion in motoring and offers the advantage of regenerative braking with similar finesse

So there you have a new high performance Turbostar, almost assembled from off-the-shelf components. While the bolted aluminium bodyshell construction is retained, it will be uprated to meet the latest Class B crashworthiness specification, involving some beefing up of thee cab ends

Bombardier is looking for Turbostar Evo to give repiability figures between the 25000 miles/casualty of the existing Turbostars and the 40,000 miles/casualty of the c2c Electrostars. 'But closer to the Electrostar' according to Mr Zappa.

Competition for Turbostar Evo

Bombardier may be the dominant supplier of diesel multiple units in the UK market to date, but on Trans-Pennine Express its new baby faces stiff competition.

Undaunted, Alstom is still trying to sell more Class 180s – such heroic optimism now recognised with a Champagne Challenge. Siemens is offering a diesel powered version of the Desiro UK electric multiple unit. This is a high power unit with 23m bodies and end doors.

CAF of Spain, which built the Heathrow Express and Northern Spirit EMUs for Siemens, is already supplying DMUs to Northern Ireland . It too has UK ambitions.

And then there is Rotem of Korea. Never heard of them? Well, The Korea Rolling Stock Corporation was renamed Rotem on Jan 1, 2002 when the company took over the heavy machinery and plant business from Hyundai Mobis

One ROSCO is considering a detailed bid from the Korean manufacturer for DMUs. Yes, really.

You know and I know that something that has a safety case, works, is reasonably priced and is building up a reliability record in quantity on your railway is the obvious best buy. British railwaymen's brains don't work like that. They are conditioned to believe that unknown quantities are automatically guaranteed to be superior to products already in service. And the makers of unknown quantities are always lured by this siren song.

Now you know and I know that the new train market is collapsing: the Trans-Pennine Express requirement is for around 130 vehicles. This means that it will be very hard to recover the development costs of a brand new design.

Given the SRA's demand for cost savings, whoever gets Trans-Pennine will demand massive reassurances on delivery and reliability, even from established suppliers. Can you see First Group/Keolis or Connex risking their new franchise on a supplier with no experience of the UK ?

Well, it all depends how much they have been infiltrated by the irrational procurement virus. Personally, I'd go for a Class 222 run-on.

Bombardier claims that the use of electric transmission will enhance performance, particularly through rheostatic braking. The lower fuel consumption of the 14 litre engine compared with the 19 litre translates into a smaller fuel load, which also reads across into better performance.

When 100mile/h operation and improved performance is combined with the station dwell times of Turbostar door configuration and floor height, modelling of the Trans-Pennine route shows shorter journey times than a Class 22X 23m DMU with end doors.

Meanwhile, industry insiders report that SRA is revisiting the issue of regenerative braking, a facility provided by the existing Networker fleets and available from the new Mk1 stock replacement electric multiple units on order.

Regenerative braking was specified for the British Rail Networker electric multiple units in the 1980s as a cost saving measure. It was expected that it would cut traction current demand by around 15%, at peak hours when the electricity supply industry charged premium rates.

However two issues meant that the Networkers never ran in regenerative mode. First receptivity (see box) was less than expected. More seriously, the high currents involved created problems for the systems protecting the 750V dc power supply. For example, a regenerating train returning 4000A to the third rail could mask a short circuit.

Given this experience, the fact that SRA is reconsidering regenerative braking suggests that cost pressures on the yet-to-be funded power upgrade continue to increase.

Complicating the upgrade timetable is the effect of Transport & Works Act requirements if road access is needed to sub-stations and track paralleling huts for which the existing equipment was brought in by rail. Conversion of a track paralleling hut to a sub-station, the simple method of upgrading used on Kent lines in the 1990s, could also require more land at remote sites.

Return to Archive -by date - by topic.