Two years ago, Bombardier decided that the ELECTROSTAR vehicle had been taken as far as possible; future requirements, particularly in the UK, require a step-change in vehicle technology.
The ELECTROSTAR EMU is a hard act to follow. Seven fleets of trains have been ordered with the first ones entering service in 1999. It was even selected for the new Gautrain in South Africa. And with another four fleets of the similar diesel-powered TURBOSTAR, it’s been a successful design, amounting to over 700 sets in total.
Bombardier’s new concept started to take shape and AVENTRA was born. The development engineers at Hennigsdorf and Derby started to pull in components and ideas from across the world. Force-cooled traction motors, as used on the AGC fleet in France, were an obvious choice. New developments in welding from Germany were matched with the CKD production techniques already used in Derby to produce a lighter, stronger vehicle.
Lightweight bogies from the TURBOSTAR also looked promising as they provided the ideal combination of lower weight – with reduced track and wheel wear – and high reliability, but adapting them for a motorised version initially posed certain challenges, as Eddie Searancke, Director of Product Engineering for Bogies, explains. “The FLEXX Eco is a very lightweight bogie that has already done millions of miles under both Voyagers and Meridians. However, they are driven by a body-mounted traction motor via a cardan shaft connected to a final drive on the bogie. For AVENTRA, we needed to find a traction motor that would fit directly onto the bogie but, as it’s an inside-frame design, there isn’t much room.”
Fortunately, a Bombardier division in Pittsburgh already has a proven drive solution for an inboard-bearing bogie design which is used in North America and Australia. It is a conventional motor with a very compact final drive. To prove the feasibility of the new traction motor installation, trials were undertaken using a modified bogie fitted under East Midlands Trains’ Class 222 Meridians operating out of St Pancras.
Throughout the design process, great care was taken to reduce the weight of the train. “We went for an all-welded construction,” explains Senior Vehicle Engineer Dean Taplin. “It allowed us not only to eliminate all the bolts that we normally use but also all the thick flanges that are needed in a bolted construction. In total, we saved over 500kg per car.”
Development of the new AVENTRA continued, striving for lighter weight without sacrificing reliability. According to Eddie Searancke, “We actually fitted some larger components than we needed to, such as the journal bearings, but this way the system needs substantially less maintenance and our calculations show that the customer will save money overall.”
LED lighting keeps the weight down even more and, taken with the other weight-saving measures, an AVENTRA car will weigh in at 30-35 tonnes compared to a minimum of 42 tonnes in Bombardier’s earlier comparable designs. That saving in mass alone reduces fuel costs but other tried-and-tested techniques can reduce energy expenditure still further.
Bombardier’s EBI Drive 50 Driver Assistance System enables drivers to achieve an economical driving style and energy savings of up to 15%. Regenerative dynamic braking saves yet more, as does the use of ‘intelligent’ air conditioning and a ‘Smart Stabling’ system to shut unused vehicles down when out of service but come back online quickly when required.
ORBIFLO feeds real-time information back to the depot so any faults can be quickly repaired and downtime kept to a minimum, although Bombardier calculates that AVENTRA will be 70% more reliable than any of its trains in UK service today.
ERTMS signalling can be fitted as standard and there is room for a second signalling system if the vehicles are to be used on different networks. An IP backbone controls all the ‘clever’ systems that keep the whole train running and enables modules connecting to the system to be readily upgraded, therefore protecting against obsolescence.
AVENTRA can run on both 25kV AC and 750V DC power – the high-efficiency transformers being another area where a heavier component was chosen because, in the long term, it’s cheaper to run. Pairs of cars will run off a common power bus with a converter on one car powering both. The other car can be fitted with power storage devices such as super-capacitors or Lithium-Iron batteries if required. The intention is that every car will be powered although trailer cars will be available.
Unlike today’s commuter trains, AVENTRA will also shut down fully at night. It will be ‘woken up’ by remote control before the driver arrives for the first shift
The result is a train that operators will find competitive to buy and cheap to run, reliable in service as well as incorporating proven innovations and ‘best-in-class’ technologies. But what will the passengers notice?
The whole train will have a clean, contemporary look. Wide gangways, similar to those on the current Class 378, will give the interior an open, airy feel while large visual displays inside and out will not only advise travellers about their journey but can also show information such as flight departures from airports and seat availability for people waiting on the platform.
Wide doors will make getting on and off quicker and easier, whilst faster acceleration will cut journey times. Fire-avoidance materials will be used for enhanced passenger safety.
With the AVENTRA, Bombardier has come up with an extremely light train that uses 50% less energy overall than a Class 319; it accelerates quickly and is very track friendly, resulting in low access charges. It is elegant and comfortable for passengers, has all the aids a driver needs and is cheap to maintain. The company believes it will be the mainstay of the UK’s regional fleet for the next 20 years. Whether the government agrees and chooses AVENTRA for at least one of the major contracts that will be placed in the near future, only time will tell.