In September 2024 the Metropolregion Hannover Braunschweig Göttingen Wolfsburg and the town of Einbeck ran their first Promptathon, Prompters' Paradise. The brief was mobility, the tool was AI and the venue was the PS.SPEICHER, Europe's largest vintage car museum. There was plenty of inspiration on the walls, some of it with a starting handle.
Team Bahn Buddy took first place. Four of the five were 42 Wolfsburg students: Ellen, Tobias, Paulo and Emanuel. The fifth was Anita, a product designer who had just finished her master's at HAWK Hildesheim and was at her first hackathon.
the delay that started it.
The idea arrived before they did. On the way to Einbeck their train was late, and the team spent the wait discussing whether Deutsche Bahn's own data could tell you which connection to trust. Participants had 24 hours to build something. They already knew what.
five people, five jobs.
Anita opened with a design thinking sprint to pin down the problem and the goal. Then the work split. Emanuel built the frontend with Anita, who designed the interface. Paulo went through the data, from reliability to cancellation rates. Tobias wrote the backend in Python. Ellen, Paulo and Anita built the pitch.
how bahn buddy works.
The app asks the rail APIs for every option on a route, around 20 to 30 connections. All of them go into one long prompt for a large language model from OpenAI, together with what the traveller cares about. The model picks the connection that fits. If price matters more than punctuality, it picks the cheap one. If arriving is all that matters, it picks the one least likely to let you down.
Tobias says the results were better than the team expected. Ellen would happily use it herself. The catch is data: judging how reliable a connection really is takes far more history than a team can collect in 24 hours. After the event Bahn Buddy became a side project, since all five had plenty else on.
the cheque, and the train home.
Four teams and around 20 people took part. Backing from partners including DLR, DB Regio Bus, HAWK and Ostfalia meant the organisers could mentor them almost one to one. A jury of five, with backgrounds in AI, e-mobility and start-ups, put Bahn Buddy first. The prize was €1,000, on the kind of cheque that needs several people to hold it.
On the way home the team got on the wrong train. The platform had been changed at short notice. In fairness, the prototype was only a day old.
two years on.
Ellen came to 42 Wolfsburg in 2022, straight after her Abitur, without much of a plan for her life. In her Piscine she sat down at a computer with no idea how to open a terminal. Students who already knew the basics showed her where to start, and she says that took away her fear of the empty page. By the Promptathon she had a women's hackathon in Mannheim behind her. She graduated in 2025, and asked what changed, she talks about mindset more than code:
I see a problem and I think it can't be that hard. Like let's just try and I think I can solve it.
That is more or less how a delayed train becomes a winning prototype. Her full graduate interview is on the 42 Wolfsburg YouTube channel.
Tobias has graduated too. He now works at Teqyard, one of the companies that backed that first Promptathon, and in April 2026 he was back at a Metropolregion hackathon, the Health Hack in Braunschweig, this time as a mentor.
The Metropolregion's interview with the whole team has more on how they built it. And if a late train has ever given you an idea, the Piscine is where you find out what to do with it.
Ellen, Tobias, Paulo, Emanuel and Anita