In our #StadlerEngineers series, we are presenting stories from our engineering teams once a week throughout March. This is especially to mark UNESCO World Engineering Day, which took place for the fifth time this year on 4 March.

Let's start this second part of the #StadlerEngineers series with a short introduction to the German rail network. Approximately 61 percent of German rails are electrified, i.e. equipped with overhead contact lines or conductor rails. Yet the proportion of kilometres travelled with electric drive systems is in fact higher than this. According to the Federal Ministry for Digital and Transport (BMDV), around 74 percent of the kilometres travelled are powered by electricity. This is because electrification is mainly carried out on busy lines, as it represents a relatively high investment that must be economically beneficial. Infrequently used lines - i.e. above all local transport routes - are mostly not electrified. Trains passing along these sections of track must therefore be operated using a different type of drive system. This "non-electric" drive usually takes the form of a diesel motor.

Now, it is part of an engineer's job to recognise existing problems and to look for solutions. One obvious solution to the problem is battery operation - a technology whose basic principle is by no means new.

In 1940, when Switzerland found itself isolated by the events of the Second World War and the supply of oil and coal could no longer be guaranteed, the government of the time decided to make use of electrical energy from hydroelectric power plants. This type of energy could be generated in large quantities in the Alps and was not dependent on supplies from abroad.

Thanks to his engineering spirit, company founder Ernst Stadler identified this as an opportunity and began converting petrol vehicles to battery operation. As early as 1943, he developed the first battery-powered rail tractor in the Stadler engineering office, for example.

This shows that electric drives have a long tradition at Stadler. Preserving this tradition means constantly optimising such systems. Their optimisation has led to various milestones in the company's history, one of which was reached not so long ago.

An unplanned world record

As part of a three-year research project, Stadler developed a battery-powered train that would function as a hybrid solution. Whenever the drive car had to run on non-electrified routes, a battery would provide the required power. As soon as the train was back on an electrified section of track, the external electricity would not only propel the train, but would also recharge the battery at the same time. This represents a potential solution for the varied configuration of the rail network in Germany.

A team based primarily in Berlin spent three years developing the "FLIRT Akku" prototype, with an intended range of 80 kilometres that would make it suitable for use on most of the non-electrified routes of the German rail network. Towards the end of the development phase, however, it became clear that the goal of 80 kilometres in battery-only mode far from exploited the full potential of the prototype.

"On the route to Stralsund, we suddenly realised that the range of the batteries was much greater than we thought," explains Evelyn Thiel, technical project manager of the FLIRT Akku vehicle, describing the first test run.

In May 2021, a battery-powered FLIRT Akku vehicle travelled 185 kilometres, and just six months later, in December 2021, the model covered a distance of 224 kilometres on just one battery charge under the eyes of external inspectors - setting a new world record.

Another unusual aspect of the development of the record-breaking train is that the project team consisted mainly of women. This is all the more remarkable given the very low proportion of women in engineering in general. Evelyn Thiel discussed the lack of parity in engineering in an interview with RailBusiness in January 2022: "For me, the question never arose as to whether it's a men's industry or a women's industry. I just do what I do best - and what I enjoy."

Her recipe for success when it comes to innovation is "to be bold and not be afraid to break new ground". That is the true spirit of engineering.

But what happened to the prototype? It has become a highly successful model: the first FLIRT Akku vehicle will be put into service by Nah.SH in Schleswig-Holstein this year. Then Deutsche Bahn plans to start operating new battery trains based on the FLIRT Akku model on the Rhineland-Palatinate network in 2025 and in the Rostock area in 2026 as part of the "Warnow II" transport project. Stadler is also expected to develop a FLIRT Akku prototype in the USA tailored to the American market.

We are delighted to have such energetic and courageous engineers (by which I mean both men and women) in our team and hope to be able to continue working on alternative, environmentally friendly mobility solutions with just as much woman power in the future.

Woman power at Stadler - it's not just a male industry

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