Home Rail News Gröna Tåget (The Green Train)

Gröna Tåget (The Green Train)

The Swedes are very good at collaboration. So it should be no surprise that a project to develop a new concept of train that is economical, environmentally friendly and able to withstand the rigours of a Nordic winter should be developed in Sweden.

The Green Train (in Swedish – Gröna Tåget) is a research and development programme which brings together institutes of higher education, infrastructure managers, railway companies and train manufacturers in a common programme.

Since its inception in 2005 the objective has been to develop a concept proposal for a new, attractive high-speed train adapted to Nordic conditions that is flexible for several different tasks on the railway and interoperable in the Scandinavian countries.

The proposal is intended to act as a bank of ideas, recommendations and technical solutions for railway companies, track managers and the manufacturing industry. It is an open source, which means that it is accessible to all conceivable stakeholders.

The research programme has already attracted the interest of the industry both in Sweden and other countries. However, despite the name, there is no finished Green Train. It exists as two weighty reports on the concepts and findings of the project.


A number of organisations contributed to the project, but the main ones were Trafikverket (the Swedish Transport Administration), Bombardier Transportation Sweden, the Royal Institute of Technology (KTH), and the Swedish state railway operator SJ.

Christer Löfving of Trafikverket explains:

“Since 1988, the Swedish railway sector has changed a lot in terms of organisation, management and responsibilities. A new infrastructure manager has been created and a number of new operators have been established. However, most of those operators are too small to carry out their own vehicle R&D work, so universities and research institutes have taken over much of that railway research.

“By rolling several of these research programmes together, we set up the Green Train Research and Development Programme. Its aim was to develop a train concept and technologies to provide more attractive, efficient and still more climate-friendly train services for long-distance and fast regional traffic.

“At the same time, we wanted to influence the development of European standards and train concepts for Nordic conditions while maintaining and further strengthening our competence to develop trains in Sweden by involving as many organisations as possible within the Swedish railway sector into the programme.”

A comprehensive range of subjects was to be considered as part of the project. These included:

• Economy and capacity

• Market, train services and conceptual design

• Attractive and functional passenger environment

• Environment – energy and noise attenuation

• Track-friendly running gear and suspension

• Carbody tilt

• Nordic weather conditions

• Aerodynamics

• Electric propulsion and current collection

• Safety and the driver’s environment

• Train maintenance

• Standards for European and Nordic countries.

Lower fares

One of the most interesting investigations was to see whether the application of new technology could bring passenger fares down. Larger trains, carrying more passengers more economically, should reduce operator costs and allow them to reduce fares.

With the X2000 train needing replacement in ten years, and with the railway system facing mounting passenger criticism for unreliability in winter conditions, this was not going to be purely an academic exercise.

Tohmmy Bustad of Trafikverket explains the concept that came out of the project:

“The Green Train is a collection of ideas, proposals and technical solutions that suit the Nordic market well. We concluded that a fast, tilting electric multiple unit train which can run at up to 250 km/h on conventional lines and maintain higher speed than conventional trains on curves was the best solution.

“A special high-speed version should also be suitable for about 320 km/h on future dedicated high-speed lines. The train must be accessible to all regardless of age or ability, have a flexible train length, and be track-friendly as well as attractive and cost effective.

“This will result in shorter travelling times and lower costs, enabling operators to charge lower fares. An attractive, functional passenger environment with a high level of comfort for all is most important so that travellers choose the train instead of other modes of transport.”

Wayward elk

The Nordic countries have some special conditions which make the job of train operators more difficult. Oskar Fröidh of KTH, author of Part A of the final report, listed some of these. “Harsh Winter Conditions” was in first place – no surprise there.

However, second was “Elk and Deer on the Line” – apparently in times of deep snow these large animals find that railway lines make excellent pathways!

The rest of Oskar’s list is more predictable. Conventional lines include some new links with speeds of up to 250 kph, but there are many sinuous slower lines with mixed heavy freight and passenger traffic.

However, Sweden, as well as Norway, Finland and parts of Denmark, is fortunate to have a wider loading gauge even than continental Europe. To date that advantage hasn’t been utilised, but the Green Train concept will have seats five across (3+2) in a cabin 3.5 metres wide.

This will give 25% more seats than a continental carriage with 300 seats in a train just 108 metres long (a comparable continental train would be 134 metres long, while the current X2000 is 165 metres). The wide-body trains will have 15% lower total costs than narrower trains (and 20-25% lower than the X2000).

In Oskar’s opinion, this lower cost base will allow modern trains to compete with airlines on short to medium length routes, and attract passengers out of their cars and onto rail.

Practical evaluation

Having come up with a series of proposals and concepts, work was needed to start to develop and evaluate these ideas. Bombardier Transportation modified a Regina 250 train to act as a test bed while remaining in regular passenger service. This allowed new technology to be assessed in real-life situations and to be exposed to the rigours of revenue-paying service and the Swedish winter.

One of the prime components to go through this process was a new bogie. Based on 25 years of experience with the concept, this is a self-steering bogie which reduces lateral forces on the track by 40%, so reducing wear and rolling resistance.

Developed from lower speed designs, the new bogie is certified for 250kph and has been tested at 303kph on a track designed for only 200kph running. The new bogie has been tested under the Regina 250 for over 500,000 km of in-service running without problems.

Active suspension is another new development. It keeps the car body centred, allowing use of the maximum gauge width, and also gives better stability in crosswinds and on curves. The result is also a more comfortable ride for passengers and once again this has been tested for 500,000 km.

The use of permanent magnet motors, developed by Bombardier in Sweden at the Västerås facility, has saved weight, given the train a better power-to-weight ratio and simplified the cooling requirements.

Snow and ice

Winterisation is not a specifically Swedish problem, but it is vital in this northern country.

“At low temperatures, snow gets in everywhere – you can’t stop it” comments Henrik Tengstrand of Bombardier Transportation.

“It comes in the cooling ducts, and anywhere else it can find. Once inside the train, or on the external equipment, it goes through cycles of freezing and melting, humidity and condensation. We even can get the underbody bombarded by stones from ballast excited by dropping ice from the train. We design to prevent it, but we still need regular deicing.”

A good aerodynamic shape helps, and thousand of virtual wind tunnel tests have resulted in a shape that has 20-30% lower drag and uses 10-15% less energy than earlier designs. “The final shape is always a compromise,” Tengstrand adds.

“The best outline for low drag resistance is not necessarily good for crosswind stability, and vice versa. However, we have had Bombardier’s best people on the problem – 5 divisions of the company in 6 different countries have been involved in the project – and we are happy with the finished result.”

In fact, having multiple partners has allowed the team to call on a large number of engineers and academics, all at PhD-level, so blurring the distinction between the two.

The name “Green Train” implies that there is an environmental aspect to the project. Reducing the energy consumption forms part of this, as does an important exercise to reduce noise.

On the train, the use of improved wheel designs and bogie skirts had a significant effect resulting in the test train at 250kph emitting no more noise than a conventional passenger train at 160kph and a freight train at 100kph. Infrastructure engineers got in on the act as well, and in sensitive areas tuned rail dampers, combined with a low height barrier close to the track and the aforementioned bogie skirts, reduced noise levels still further.

Energy-saving techniques on which the rail engineer has reported before have also been employed. Regenerative braking and eco-driver management systems are both part of the Green Train concept.

The design of the train’s interior hasn’t been neglected. A team of 16 students of Konstfack, the University College of Arts, Crafts and Design, have worked on the project under the guidance of Olle Lundberg. Thin-backed seating designs maximised legroom for passengers, and the wide body allowed for 3+2 seating in economy class and 2+2 in first class.

Luggage and wheelchair facilities were taken into account, and a special entrance lobby with a low floor and an integral wheelchair lift designed. “In winter, people have a lot of coats”, added Lundberg, “and we had to find space for them as well.”

New train

So that is the Green Train. A concept more than a finished design, a test bed not a new class. However, the new concepts are already bearing fruit as can be seen from Swedish Railway’s newest train – the SJ3000. Build by Bombardier, which knows it as the X55, this new four-car set entered service in February 2012.

Externally, some of the Green Train’s pedigree can be seen as several winterisation ideas have been included in the design. The cab front is smooth without any gaps between panels which could become packed with snow and ice. The windscreen wiper parks vertically so snow won’t gather on it, and the light clusters are on the outboard edge of the front panel, so when snow slides down off the heated windscreen, it doesn’t obscure the lights.

The coupler has a cover that has to be removed before use, but which stops snow and ice entering into the mechanism. There is an integral rubber gaiter for the same reason. The bogies are also specially engineered. All the cables and hydraulic pipes are tucked neatly out of sight, again to prevent ice build-up, and the bump stops are angled and plastic-covered so any ice will break up easily and slide off.

On the train sides, air intakes are located right up at the edge of the roof, to keep them away from the powdered snow that blows around the train while it is in motion. Under the frames are big open spaces so that snow can swirl around and fall away, without compacting on under-floor mounted equipment.

Inside, the car body is wide and spacious, although the seating is only 2+2 in both first and second class. There is a bistro car reminiscent of one from a Virgin Pendolino, and a fancy lift mechanism to get wheelchairs from ground level up to the main aisle.

So parts of the Green Train are now in service. No doubt more of the technology will follow in years to come.


Nigel Wordsworth BSc(Hons) MCIJhttp://therailengineer.com
SPECIALIST AREAS Rolling stock, mechanical equipment, project reports, executive interviews Nigel Wordsworth graduated with an honours degree in Mechanical Engineering from Nottingham University, after which he joined the American aerospace and industrial fastener group SPS Technologies. After a short time at the research laboratories in Pennsylvania, USA, Nigel became responsible for applications engineering to industry in the UK and Western Europe. At this time he advised on various engineering projects, from Formula 1 to machine tools, including a particularly problematic area of bogie design for the HST. A move to the power generation and offshore oil supply sector followed as Nigel became director of Entwistle-Sandiacre, a subsidiary of the Australian-owned group Aurora plc. At the same time, Nigel spent ten years as a Technical Commissioner with the RAC Motor Sports Association, responsible for drafting and enforcing technical regulations for national and international motor racing series. Joining Rail Engineer in 2008, Nigel’s first assignment was a report on new three-dimensional mobile mapping and surveying equipment, swiftly followed by a look at vegetation control machinery. He continues to write on a variety of topics for most issues.


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