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Digital coupling trials in EU to be completed by the end of 2022

6 July 2022
Reading time ~ 10 min
An example of a digital coupling
An example of a digital coupling. Source:
Belov Sergey, Editor-in-Chief, ROLLINGSTOCK Agency
Reading time ~ 10 min
Litvintsova Olga, Editor of International Projects, ROLLINGSTOCK Agency

EU: A train with two selected coupling technologies from Dellner and Voith is now running in trial mode across Europe. It is planned to be shown at the InnoTrans exhibition in Berlin in September. At the end of the year, an automatic coupling to become the main one in Europe to serve for the increase of transportation automation will be defined.

The need for development

Nowadays, most freight wagons in the EU countries are coupled manually with the help of screw coupling, while in other countries around the world automatic technology is used. Europe is the only region where automatic coupling has not yet been introduced. More than 100 years have passed since the introduction of the automatic coupling in a number of countries. For example, an automatic coupling has been used in the US rail transport since 1893.

Manual wagons coupling obviously has a number of disadvantages, including the overall inefficiency of the process due to the need for large time costs (it takes about 60 min to couple a 25-car train), the use of manual labor and the risk of increased injury.

An example of wagons screw coupling in Europe An example of wagons screw coupling in Europe. Source:

Currently, Europe pays an increased attention on the development of rail transport as a driver to reduce CO2 emissions. However, the demand for transportation by rail should be guaranteed by increasing the efficiency and automation of the industry. In this regard, the goal to develop and implement a digital automatic coupling (DAC) for freight wagons was set. The technology should involve not only the rolling stock coupling itself, but also its brake lines, power lines and data transmission lines. It should also provide the ability to makeup longer and heavier trains, use electro-pneumatic brakes, which allow to increase the speed of movement and shorten the stopping distance of the train, as well as constantly monitor the wagons and cargo condition via sensors.

Project launch

The project is supervised by the Germany’s Federal Ministry for Digital and Transport (BMDV). It was with their support that a research project was implemented in 2016 to create innovative freight wagons, where the prospects for introducing an automatic coupling were studied.

In 2019, BMDV already commissioned a study to investigate the feasibility of moving freight rail transport to a digital coupling across the EU. The research showed that many transportation market players supported the introduction of DAC.

A pilot project for the DAC implementation was presented on June 22, 2020. It involves DAC prototypes tests in order to select the most suitable solution. Financing in the amount of €13 mln was allocated for the implementation of the project until the end of 2022. The participating manufacturers of the DAC project at its start were:

    • Dellner with one of the Scharfenberg automatic coupling systems type,
    • CAF with an automatic coupler based on the SA-3 technology common to the railway networks with 1520 mm gauge (at the beginning of 2021, Dellner bought this division from CAF),
    • Voith also with one of the Scharfenberg automatic coupling system type,
    • and Wabtec represented by the acquired Faiveley Transport with automatic coupling of Schwab technology.

Coupling options selected for the DAC project Coupling options selected for the DAC project (enlarge). Source:

To implement the project and conduct tests, a consortium was created, which included six companies from Germany, Austria, Switzerland and France. Thus, Deutsche Bahn and its DB Cargo subsidiary, the Swiss and Austrian freight operators – SBB Cargo and Rail Cargo Austria, as well as GATX Rail Europe and VTG and Ermewa, became members of the consortium.

Test progress

DAC project roadmap consists of 3 phases. At the first, from June to September 2020, preparatory activities were carried out for testing. As part of the second, the technologies themselves are tested, while the stage is divided into two phases. The third stage runs in parallel to the entire project and includes its communication support. For example, a train with digital couplers will be presented at Innotrans 2022 in Berlin in September.

In the first phase of prototypes trials, four groups of railcars were formed, each consists of 3 wagons of the same type: Eanos-x059 four-axle gondola car, Hbbins 306 two-axle boxcar and Zags 119 four-axle tank car. These railcars are among the most popular in European railway transport – 269,700 of such freight wagons or about 40% of the total fleet are being operated on the EU network.

Railcars used for the digital coupling trials (from left to right): Hbbins 306 two-axle boxcar, Eanos-x 059 four-axle gondola car, Zags 119 four-axle tank wagon (enlarge) Railcars used for the digital coupling trials (from left to right): Hbbins 306 two-axle boxcar, Eanos-x 059 four-axle gondola car, Zags 119 four-axle tank wagon (enlarge). Source: DB Cargo, GATX

Railcar configuration for trials Railcar configuration for trials. Source:

Each railcar was equipped with 3 types of test equipment: for mechanical and pneumatic performance, power supply level and reliability of data transmission analysis. Each of the possible tests was carried out 5 times.

Mechanical tests were carried out for various potential operating conditions. At the same time, various railcar loading options were chosen, as this affected the operation of the tested wagons, made it possible to check the operating ranges of automatic coupling and their load capability. Tests were also carried out while driving in curves at various speeds. For example, the tests were conducted on an S-shaped curve with a radius of 150 m with an intermediate straight line of 6 m. During the tests, the boxcar was in the middle of the coupled railcar group, since particularly two-axle wagons are most susceptible to derailment. At the same time, neighboring wagons were fully loaded. To determine the automatic coupling endurance strength, the longitudinal force was gradually increased starting from 100 kN.

Various tests were also carried out to check power supply and data transmission systems. It included a test for measuring the resistance of contacts, analyzing the insulation of coupling, measuring the duration of contact during the connection process.

The environmental chamber tests were aimed at verifying the correct operation of the digital coupling in extreme temperatures. In this case, tests were also carried out on the coupling of two empty wagons (box and tank cars) and one fully loaded (gondola car). The tests were conducted at temperatures ranging from -25 to +45° C, various environmental conditions (from dry surface to a 3-5 mm rain crust in 3-5 mm on an automatic coupling), as well as at different speeds in the range of 2-5 km/h.

One of the test coupling elements in the climatic chamber One of the test coupling elements in the climatic chamber. Source:

Based on the results of the trials first phase, on September 21, 2021, two automatic couplers that showed the best results were determined. Thus, only DAC prototypes of the Scharfenberg system from Dellner and Voith were admitted to the second phase. As part of it, tests are already being carried out in real operating conditions, and the composition of the train is gradually increasing to 24 cars. Also, the groups, which previously consisted of 3 railcars, were increased to 5 wagons due to the inclusion of a Sgmmns(s) 40 flatcar and another Zags 119 tank car.

In 2021, the train with installed Dellner and Voith coupling prototypes ran along selected routes in Germany, and from the beginning of 2022, operation continued through the territory of Austria and Switzerland. SNCF is going to test DAC in October. The purpose of the real settings testing is to gain a deeper understanding of the tested couplers and clarify some of the queries that arose during the first phase. In general, the tests will provide various scenarios, including trials on the station tracks, lowering the wagons from the marshalling yard, etc. Suitable components for power supply and data transmission must also be selected.