WITH a production run spanning nearly two decades, Bombardier’s Electrostar EMU has become a familiar sight across the rail network of southern and eastern England. However, after 17 years and more than 2000 vehicles, Electrostar production is now coming to a close and the batch of class 387 trains currently being built at Bombardier’s Derby plant will be the last.

Market demand for greater energy efficiency and reliability and more stringent requirements for crash resistance and accessibility for passengers with reduced mobility have driven the development of a successor to the Electrostar and a complete rethink of Bombardier’s EMU for the British market.

Crossrail Aventra TfLThe new train seeks to draw on years of experience from the production, operation and maintenance of Electrostars, proven features from other Bombardier rolling stock designs, and feedback from the industry to deliver a train which can build on the Electrostar’s success in Britain’s growing but increasingly-competitive EMU market.

Following research and consultation with train operators, rolling stock owners, passenger focus groups, and infrastructure managers, Bombardier formed a cross-functional team of around 100 people including procurement, manufacturing and maintenance staff and representatives of core suppliers to develop and design what ultimately became known as the Aventra.

The freedom to design a new train from the ground up means Bombardier is starting out with a very different product. While the Electrostar evolved over a long period, spawning variation in components and train management systems, Aventra was conceived as a modular platform with a fixed core design which will remain constant, regardless of how the train is configured. This means Bombardier can offer a 145km/h suburban train or a 200km/h inter-city train with a choice of 20m or 23m-long vehicles and formations ranging from three to nine cars using the same core design.

Bombardier says it has focussed on maintainability and energy efficiency throughout the design process with an ethos of ‘proven innovation’ drawing on experience and technology from elsewhere in the Bombardier group. The lineage of Aventra can be traced back to established European EMU designs such as the Francilien for Paris and the Talent 2 in widespread operation in Germany, and the new train shares common features and technologies with these products. Heating, ventilation and air-conditioning (HVAC) is based on the system supplied by Mitsubishi Electric subsidiary Melco for London Underground ‘S’ Stock trains, which, like the Aventra, were built at Bombardier’s Derby plant.

As part of the design process, Bombardier reviewed the location of every item of electrical and mechanical equipment, drawing on experience from the maintenance of Electrostar fleets to optimise the positioning of equipment for ease of access at depots. From the outset a group of service engineers was involved in the development process, with a right to veto design decisions that might compromise maintainability.

Electrical cabinets at the outer ends of the Electrostar have been eliminated with the equipment redistributed through the train, and with more systems controlled through an IP backbone the amount of wiring has been reduced. Software for the entire train can be configured from a single point - on the Electrostar this had to be done individually on each vehicle. Under the floor, all propulsion equipment including line converters and auxiliary converters has been consolidated into a single unit, reducing and simplifying wiring.

The train is equipped with a diagnostics and prognostics system, which remotely communicates the maintenance status of onboard systems to a central computer. Bombardier says the train will ultimately generate its own service orders and enable operators to easily monitor and adjust non-safety critical systems on a fleet-wide basis.

Aventra retains the extruded aluminium bodyshell structure of the Electrostar, although there are a number of important changes in this area, particularly around the driver’s cab, where frontal impact absorption elements have been redesigned to meet crashworthiness standard specified in the Locomotives and Passenger Rolling Stock (Loc & Pas) TSI. Larger windows give standing passengers a clearer view out of the train - a welcome improvement for taller travellers.

Intelligent stabling to reduce power consumption when not in service and a load management system which automatically adjusts the HVAC system according to passenger volume and ambient temperature are provided.
Bombardier says fewer components are used in the Aventra interior, compared with the Electrostar, reducing weight and simplifying assembly and maintenance. For example, wood flooring used on the Electrostar has been replaced with aluminium, which as well as being lighter is easier to fit.

A significant weight saving has been achieved through the use of Flexx Eco inside-frame bogies. This is a development of the successful B5000 bogie, which has have been in widespread use in Britain for over a decade on the class 220/221/222 family of inter-city trains and on the more recent class 172 Turbostar DMU. The Flexx Eco weighs 3850kg, compared with 6150kg for the Series 3 bogie used on the Electrostar, while unsprung mass has been reduced from 3.6 tonnes to 2.7 tonnes. With Britain’s variable track-access structure favouring track-friendly bogies, this gives Aventra operators another cost advantage over older trains.

The Aventra is equipped with a new design of bogie-mounted traction motor which is rated at 225kW, compared with 250kW for the Electrostar - a reflection of the reduced mass of the new train. On the nine-car train for Crossrail 55% of axles are powered, providing acceleration of 1m/s2.

All variants will be equipped with 1450mm-wide sliding plug doors, which are wider than those of the Electrostar, and door opening speeds can be adjusted through the onboard computer.
The Aventra gives Bombardier a TSI-compliant EMU for the British market, and the design conforms to the TSIs for Locomotives and Passenger Rolling Stock (Loc & Pas), Passengers with Reduced Mobility (PRM), and Control and Command Signalling (CCS).

While Bombardier has no plans to produce a diesel version of Aventra, consideration has been given to operation on non-electrified lines using batteries. “We considered batteries from the start and we’re ready to go, should the market be interested,” says Mr Mark Ellis, Bombardier head of engineering, UK projects.

The first order for Aventra came in February 2014, when Transport for London awarded Bombardier a £1bn contract to supply 66 nine-car 25kV 50Hz class 345 suburban trains for the Crossrail east-west link across London, with an option for 18 additional sets.

Each 200m-long train accommodates up to 1500 passengers, 450 of them seated, with four wheelchair spaces.

The interior layout of the class 345 reflects the mixture of different journey types on the route, with short-distance ‘metro’ trips in the core, longer-distance commuting from the peripheral stations, and travel to and from Heathrow Airport.

The outer cars (1 and 7/9) and an intermediate car in the centre of the train (car 5) have longitudinal seating, reflecting the positioning of escalators at core stations, providing more standing space in the sections of the train where passenger density is likely to be highest. Full-width gangways improve passenger distribution, provide additional standing space, and give a clear view through the train.

Bombardier has invested £20m in its Derby plant to expand capacity for production and testing of the Crossrail fleet. The centre piece of the project was a 10,000m2 testing and commissioning facility, which is equipped with four 250m-long tracks, each capable of accommodating a complete nine-car train. All four lines in the shed are electrified with full-length pits for underfloor access. Each test bay is multifunctional and can be used for type testing or final acceptance testing.

Bombardier secured a second order for the Aventra in July 2015, when Transport for London awarded a £260m contract to supply 45 class 710 suburban EMUs for London Overground. The fleet will comprise 14 dual-voltage (25kV 50Hz ac and 750Vdc) sets with longitudinal seating for Euston - Watford dc services and the newly-electrified Gospel Oak - Barking line; and 31 ac-only trains with longitudinal seating for the West Anglia suburban lines and the

Romford - Upminster line. Bombardier says production will start before the end of the year and deliveries are due to begin in December 2017 with the first train set to enter service in May 2018. Bombardier will maintain the fleet under a separate 35-year train services agreement.

Last month Britain’s Department for Transport (DfT) announced it had selected Abellio as preferred bidder for the East Anglia franchise, heralding a third major order for Aventra. In a deal worth around £1bn, Bombardier will supply 22 10-car and 89 five-car suburban trains, which will enter service on West Anglia and Great Eastern routes from 2020 onwards.

With three major orders already booked, Aventra is already making an impact in the British passenger rolling stock market. With more major tenders in the pipeline, Bombardier is confident the new train will be a worthy successor to the Electrostar, and a product that can emulate its predecessor’s commercial success.


Crossrail fleet set for May 2017 launch

THE completion of the first class 345 Aventra EMUs for Crossrail marks an important milestone for the £14.8bn project to build a new east-west rail link across central London, connecting the Great Eastern Main Line (GEML) and Abbey Wood with the Great Western Main Line (GWML) and Heathrow Airport.

At the time of writing, two sets have been completed with three trains on the production lines at Derby. One of the completed trains was moved from Derby to the Old Dalby test track south of Nottingham on August 19 and delivery of the first train to Ilford depot in east London is scheduled for November.

There will then be a period of compatibility testing and mileage accumulation on the GEML, with driver training due to commence in April 2017. The first trains will enter passenger service with TfL Rail on London Liverpool Street - Shenfield GEML suburban services in May 2017.

The trains will use the British TPWS and AWS train protection systems on the GEML, with CBTC in the core tunnels and ETCS on the Great Western Main Line from London Paddington to Heathrow Airport and Reading. Testing of operation under CBTC will begin at Old Dalby before the end of this year and ETCS testing will start in early-2017.

A fleet of 15 trains will initially operate on the GEML as seven-car sets. The first nine-car train will be delivered to Crossrail’s main depot at Old Oak Common in west London in early 2018 and the full-length sets will be introduced on London Paddington (high level) - Heathrow Airport services in May 2018.

Mid-2018 will also see the start of dynamic testing with class 345s in the core Crossrail tunnels beneath central London.

The first section of Crossrail will open between Paddington and Abbey Wood in December 2018. The Shenfield line will be connected to the Crossrail tunnels in May 2019 and the full route from Shenfield and Abbey Wood in the east to Heathrow and Reading in the west will be operational by December 2019. All 15 seven-car trains will be lengthened to nine cars by the end of 2019.

The trains will be maintained by Bombardier at Old Oak Common under a 32-year fleet servicing contract.