Hamburg has the first self-propelled S-Bahn

Engine driver Rainer Dietz does nothing. His hands rest on the desk in front of him. And yet the S2 drives off. The train accelerates quickly and evenly and leaves Berliner Tor station just a few seconds later.

It is 10.08 a.m. on Thursday morning and Dietz is monitoring the first passenger journey on a purely digitally controlled S-Bahn in Hamburg. According to the operator, this makes it the first train in the world to run alone.

Self-driving trains already exist in closed systems such as underground and suspension railways or on high-speed railway lines specially built for autonomous traffic, explains Kay Uwe Arnecke, Managing Director of S-Bahn Hamburg, while the S2 continues in the direction of Bergedorf. However, such closed systems are not comparable to railway traffic, where trains of all kinds share tracks, where there are points, signals and a lot of free, sometimes uncontrollable, space around the trains. For normal railway operations, the digital S-Bahn in Hamburg means the entry into "a new era", the digitization of the rails represents an "important change of era".

Transport Senator Anjes Tjarks (Greens), who accompanied the first passenger journey on the self-propelled S-Bahn, said that the digitization of the route would allow the trains to run more closely. Up to 30 percent more trains are to be used on Hamburg's existing S-Bahn tracks in the future. According to Tjarks, more frequent services mean better services for passengers, shorter waiting times at the stations and thus more comfort in local transport. "The aim is to extend the system to the whole of Hamburg and thus raise the performance of the entire network to a new level."

By the end of the decade, the Hanseatic city's S-Bahn network should be largely digitized. It is currently 147 kilometers long. Six lines serve 69 stops. Instead of the four trains of the 474 series, which were previously retrofitted with the new digital technology, there should then be almost 200. 64 more trains from the latest 490 series have already been ordered with digital technology and will be delivered successively from 2025. The federal government has already invested 31.5 million euros in a digital interlocking. It could go into operation in 2029 and lead to smoother traffic with more frequent intervals, especially on the busy tracks in the city center.

For Dean Balatinac, Head of Sales Trains at Siemens, the digitization of trains and routes has a third advantage. In addition to more punctuality and greater utilization of the existing routes, energy could be saved through optimized driving operations. A topic that is currently playing a role all over the world. Using the Hamburg S-Bahn as an example, more than a third of the electricity could be saved.

The S2 has now arrived in Bergedorf. Engine driver Dietz leaves the driver's cab and can watch from the platform how the train drives alone into the turning track and a few minutes later - just as driverless - drives back to the platform in the other direction of travel. The train is monitored by the signal box.

The digital S-Bahn also runs alone on the 23-kilometer route between Berliner Tor and Bergedorf. You can imagine the system like an autopilot in air traffic. In addition, the train independently ensures that the doors can be opened and closed. Engine drivers like Dietz only monitor the route while driving and whether the computer on board is working properly. If in doubt, he can intervene at any time and control the S-Bahn manually again.

Automated operation is made possible by the interaction of two technologies. One is the European train control system ETCS, which, to put it simply, replaces the previous signaling and emergency braking systems of the European railway companies and also digitizes them. For the route between Berliner Tor and Bergedorf, for example, around 500 information points, so-called balises, flat yellow boxes that send signals to the train, have been laid on the tracks. When one of the four automated trains is on the route, the train traffic lights, which otherwise use green and red lights to indicate whether the next section of the route can be used, pause.

The second system is called ATO for short and stands for Automatic Train Operation. A computer on board the train takes over control, acceleration, braking - and in the case of the digital S-Bahn in Hamburg also opening and closing the doors. The computer is in constant contact with the balises, so it can react independently to each signal and, for example, adjust the speed so that the train passes the next signal when it is green instead of having to stop at it when it is red.

That was still unusual for him, says train driver Dietz in an interview with Transport Senator Tjarks, who spends the return journey to the Berliner Tor in the driver's cab. He always had the impulse to want to drive himself, says Dietz. Ultimately, however, it is a matter of practice, and using the computer is a system that you have to relearn. Dietz has been running S-Bahn trains since 1989, and has also been using the digitized 474 trains again and again for the past two years. People have also traveled with him. The first trip in regular operation is something different.

In 2018, Hamburg set out to digitize its S-Bahn network. In July 2018, the Senate of the Hanseatic City entered into a partnership with Deutsche Bahn and Siemens Mobility. Since then, the three partners have invested around 60 million euros in the project.

At the ITS World Congress in October 2021, they presented highly automated rail operations for the first time. During the congress there were test runs for its participants - almost a year later the trains have made enough test runs to go into normal passenger service.

And as a passenger, do you notice that you are sitting in a very special train? Anyway, Senator Tjarks thinks it feels "good." And for all those who don't find starting and braking any gentler than with a good train driver, the S-Bahn has had all four converted trains on the S2 wrapped in extra white. “Digital S-Bahn Hamburg” is then written on it.

However, the train only runs on its own on the section between Berliner Tor and Bergedorf. Rainer Dietz drives the train the rest of the way between Berliner Tor and Altona. Then his hands are not on the desk, but on the driving lever.