Always keep your cool: the DAC put to the winter test

To ensure that the Digital Automatic Coupling (DAC) can withstand the challenges of European rail freight, it must be highly robust. That includes a certain degree of resistance to ice and snow, which are particularly common in the Alps during winter. The DAC winter tests focused precisely on this resistance over a test period of four weeks.

Real-world conditions beat the lab 

To test the resilience of the DAC technology, the ÖBB team – consisting of a test coordinator, a test observer, an operational test manager, a shunting supervisor, a train driver and a wagon technician – carried out coupling and shunting tests under the most realistic conditions possible. Unlike the climate chamber in the lab, real-life testing in the field reveals even the smallest weaknesses.

We want to see errors! 

Even with the best technology, problems can sometimes arise. For instance, lubricants can become viscous in very cold temperatures and impair the actuators (devices that convert energy into motion) for uncoupling. Similarly, mechanical components may become significantly stiffer in icy conditions, and too much snow can interfere with the electrical contacts of the couplings.

Rubber seals, used among other things in electrical contacts and air lines, may become rigid in the cold and may therefore cause faults. However, RCG tester Anna Kurzecka does not share the concern that coupling in sub-zero temperatures might cause problems: “Our approach is different. We are happy about every error we find. Only then can we develop DACs that make rail freight transport more efficient and safer.”

It's colder in the shade 

The search for a suitable test site for the DAC demo train finally led the ÖBB team to Schwarzach-St. Veit station in the Salzburg Pongau region. At 594 metres, it is not exactly located in alpine terrain. So why not choose a station further up? Anna Kurzecka explains: “Although the stations at Böckstein and Mallnitz-Obervellach are situated at over 1,100 metres, temperature inversions often make them warmer. Schwarzach-St. Veit was ideal for us because it is surrounded by mountains and remains in shade practically throughout December and January.”

Couple, uncouple, couple – and start all over again 

For three weeks in January, the DAC test team conducted countless coupling tests at Schwarzach-St. Veit station. The team, working in minus 15 degrees, 20 cm of fresh snow and freezing rain that coated the couplings, was pushed to its limits as well. They repeatedly tested the mechanical coupling process and paid close attention to how the electric drives reacted when uncoupling at the push of a button. Particular focus was also placed on the couplings’ air connections, which are essential for brake performance.

After the tests in Schwarzach-St. Veit, the DAC demo train underwent another endurance test in February. “We went to Böckstein with our train driver, pulled the train apart so that snow could reach every last nook and cranny, and then left it parked there for ten days.” Such long-term exposure is not uncommon in freight operations, where individual wagons may stand idle for extended periods.

Surprising results 

So, what is the verdict after four weeks of intensive testing? “The conditions were very good, even though we had hoped for a bit more fresh snow.” In the end, the manufacturers did a great job with their DACs. “To be honest, I didn't expect it to work this well,” Anna concludes, – a successful outcome even if she had secretly hoped for one or two more errors.

Funded by the European Union. Views and opinions expressed are however those of the author(s) only and do not necessarily reflect those of the European Union or the Europe’s Rail Joint Undertaking. Neither the European Union nor the granting authority can be held responsible for them.

The project is supported by the Europe’s Rail Joint Undertaking and its members.