Trolleybuses in Germany

Until a few years ago, electric buses were a rarity in German mass transit. At the beginning of the millennium, they still existed in three cities: Eberswalde, Esslingen and Solingen. Since the end of the oil price crisis, the concept was no longer particularly interesting, a relic of a bygone era. Abroad, especially in Switzerland and Eastern Europe, it was always different. The cities in Germany that never got rid of their trolleybuses are happy about it: "We in Eberswalde love our trolleybus, the 'Strippe'. It is an integral part of the city's identity and definitely an important image factor. "All the better that the trolleybus with green electricity is also making a contribution to the traffic turnaround," says Anne Fellner, First Deputy Mayor and Head of the Building Department of the City of Eberswalde. To understand why she is so enthusiastic and the trolleybus leads a shadowy existence at the same time, it is worth taking a look at the history of trolleybuses.

The idea is over a hundred years old and, like that of the electric train, originated with Werner von Siemens. As early as 1882, he was testing his "Elektromote" near Berlin: an electrically powered open carriage supplied with electricity via an overhead line and a trailing cable. At that time, Kurfürstendamm in Halensee was more of a dirt road on which the vehicles weighing tons with iron-tired wooden spoked wheels could barely manage. With the bumpy ride, the constant power supply is prone to error. Only in terms of cost does the idea win out over a train running on tracks. After a few months, Siemens discontinues the experimental line.

Nevertheless, engineers around the world try their hand at improvements to the "trackless railroad: At the 1900 World's Fair in Paris, an electric bus line runs through the Bois de Vincennes urban forest for the first time. The former Siemens engineer Max Schiemann develops the current collector with collector shoe that is still in use today and is based on an invention by the Briton Alfred Dickinson. He built a line in Saxon Switzerland and presented his technology at the Turin World's Fair in 1902. Schiemann had his trackless trains transport not only passengers but also mail and parcels. However, like almost all of his competitors, he remained economically unsuccessful. After the First World War, almost all trackless railroads in Europe disappeared.

With smoother, tarred roads and rubber tires, the signs change after the war. Called the "trolleybus," typical of the time, the trolleybus spreads around the world in the interwar period. It returns to Germany in 1932, when RWE builds a trolleybus line from Idar to Tiefenstein as an extension of the RWE tramway. With both streetcar tracks and diesel in short supply during the wartime economy, new systems are built in numerous cities. In large cities such as Hanover, Leipzig or Berlin, they are a supplement to the tramway. After the war, little changes in direction. Especially in smaller cities, trolleybuses are a welcome alternative to aging streetcar networks, since there is no need to build or renew tracks. In the 1950s, there was a peak of trolleybuses in Germany that was never reached again afterwards. With increasingly car-friendly cities and lowered taxes for diesel, the technology is gradually losing relevance and the disadvantages are coming to the fore: new vehicles are hard to come by, and the overhead lines require a lot of maintenance. Since a trolleybus can only run where there is an overhead line, it is also not particularly flexible. Gradually, almost all cities switch to diesel operation. The last to go out of service were the Duobus Essen and the trolleybus in Potsdam in 1995. Esslingen, Eberswalde and Solingen were also considering the end of trolleybuses at that time, but in the end this did not happen. In 2015, a study carried out as part of the Mobility and Fuel Strategy (MKS) came to the conclusion that acceptance was suffering because, unlike abroad, there was "no positive trolleybus culture throughout" in Germany.

Numerous cities in Switzerland, Italy and Eastern Europe have invested in their systems in recent years or are even building new ones, such as Avellino in Campania recently. "From a transport planning perspective, it is actually difficult to understand why there is rather little interest in the battery trolleybus in Germany. The systemic advantages are manifold, the buses are also economical under certain operating conditions, and the system is locally emission-free," says Petra Strauß, division manager for public transport planning and evaluation at PTV Transport Consult. Prof. Matthias Thein, who researched improvements in trolleybus technology at the West Saxon University of Applied Sciences in Zwickau until 2022, adds: "The battery trolleybus is the unrecognized genius in public transport. Its battery mass per person is about the same as a pedelec and its range is virtually unlimited." The small traction battery makes it possible to extend lines flexibly without installing overhead lines in problematic locations, he said. Unlike trains, where the current-carrying rails also form the return line, trolleybuses always require two parallel lines for power supply. So-called air switches are therefore required at the branching points of the lines. These structures, which are suspended in the air high above the road junctions, tend to freeze, are difficult to maintain and can only be driven slowly because the rods otherwise slip out of the guide and force the bus to stop. In Switzerland, they are avoided altogether wherever possible on new trolleybus lines.

Battery technology makes this possible. Petra Strauß explains: "The battery trolleybus combines the proven and reliable technology of conventional trolleybus systems with modern battery storage technology. This makes it reliable and very efficient. For lines with high passenger volumes and long round trips, it is therefore particularly suitable." She reports on how the consulting firm has estimated the possibilities for its use in Germany: Of about 70 urban areas that need a high-quality, dense public transportation system and that would be structurally eligible for trolleybus systems, only half have streetcars, she said. About of the 20 cities identified are topographically mobile, with an average slope above 4%. "This is where the battery trolleybus could be particularly suitable for introducing zero-emission mass transit," Strauß added.

The focus on cities in mountainous regions is obvious: During the energy-intensive uphill journey, the overhead line supplies the buses with energy ("in-motion charging"); on the downhill journey, braking energy is fed in. Such an operation has been tested in Prague since 2017: The new Line 58 operates largely like a battery bus, charging at the terminals. However, an overhead line was installed for the uphill journey from Palmovka - located in the valley floor - up to the Letňany district. 1.4 km of the nearly five-kilometer route are equipped with it.

Something similar is currently being planned in Marburg: Germany's fourth trolleybus system is possibly to be built here. The city in the Lahn valley is planning a ring service from the city centre and the two railway stations to the hospital and university site on the Lahn hills. So far, about 5,000 people reach this location daily with the natural gas buses of the municipal utility company. The idea is that in the future the new trolleybus lines could serve the particularly highly frequented routes in the bus network.

Marburg's mayor Nadine Bernshausen reports on how the considerations came about in Marburg. In 2016, Stadtwerke Marburg had contacted the responsible department in the Federal Ministry of Transport after a sketch for a trolleybus in Marburg had been drawn up on the basis of the MKS study. This was followed by a feasibility study, the results of which should also be transferable to other mountainous cities. "Although several cities (such as Berlin and Tübingen) were discussing the introduction of hybrid trolleybuses at the time, only the city of Trier was enthusiastic about preparing a corresponding study," Bernshausen recounts. They considered how many metres of overhead lines, substations and buses would be optimal before going into the planning approval procedure. On 29 September, the city council decided to start the procedure.

A binding decision on whether the BOB Marburg project will be implemented has not yet been made. After a positive conclusion of the planning approval procedure (probably at the end of 2024), an updated examination will take place. This will be done against the background of the fact that the technology of pure battery buses is developing strongly. If it were possible to serve the Lahn Hills with pure battery vehicles in the future without any problems and in a climate-friendly manner, it would make sense to dispense with the costly construction of the overhead line infrastructure. Therefore, an assessment of the current performance and economic efficiency is to be carried out. Then the final decision on the implementation of the BOB project lies with the city council, which can ultimately also decide against the implementation of the project. Commissioning is expected for the timetable change 2030/31 at the earliest.

One of the reasons that German cities are hesitant about new trolleybus networks is that, unlike charging points for battery buses, overhead lines are considered "spatially effective" and require planning approval before construction can begin. As a result, the conversion takes much longer. In Berlin-Spandau, a planned trolleybus network was scrapped almost unnoticed because double-articulated buses with battery technology are now available. In response to an inquiry, the Senate Department for Mobility, Transport, Climate Protection and the Environment said that double-articulated vehicles could be used from 2027. First, the stops and turning points would have to be adapted. Such long lead times do not make the drive turnaround any easier, says Petra Strauß of PTV Transport Consult. "The trolleybus infrastructure can be built comparatively quickly; after all, it's often limited to poles and overhead lines. Nevertheless, the same procedure has to be gone through as with streetcars, for example." Kiel had decided a year ago in favor of a streetcar and against a bus rapid transit system with battery trolleybuses after a comprehensive system comparison. Nevertheless, it would be wrong to reject the trolleybus as an alternative across the board, says Strauß. Depending on the application, the battery trolleybuses could certainly be more economical than a pure battery bus or a streetcar, but that depends on many influencing factors and must always be examined on a case-by-case basis.