DAC and ETCS Through the Eyes of German Experts: Innovation Full of Questions

The Digital Automatic Coupler (DAC) is often hailed as the key to modernizing rail freight transport, but opinions among experts remain divided regarding its true benefits and challenges.

The German transport journal Deutsche Verkehrs-Zeitung published responses from experts on five key theses about the DAC. Contributions were provided by Jan Elfenhorst, Executive Director of Rail & Strategy EP Logistics International and board member of Die Güterbahnen (The Freight Railways), and Ralf Jahncke, Director of the consulting firm Transcare.

Thesis: The DAC is essential for the digitization of rail freight transport, which cannot progress without it.

Jan Elfenhorst: No. The DAC can be an important component of the industrialization and digitization of rail freight transport, but it is neither its sole prerequisite nor the "savior" some would like to portray it as. Politicians’ enthusiasm likely stems from the fact that the DAC is a good idea that is easy to understand. However, the future of rail freight transport will depend more on complex innovations, such as the European Train Control System (ETCS). While the DAC can automate individual processes as a "complete package," smaller, more cost-effective solutions could also achieve significant efficiency gains. Other digital technologies are also important. A holistic approach is necessary to fully realize the potential of digitization. However, digitization should not be conflated with standardization, harmonization, and industrialization.

Ralf Jahncke: No. Digitization in rail freight transport often involves applications that are not safety-critical and can be implemented via radio-based technologies. While powering sensors and information units through the DAC would be convenient, this can also be achieved through decentralized solutions, such as battery technology or even photovoltaics. Monitoring systems that operate this way have already been installed on wagons for years. The DAC is not strictly necessary for commercial digitization, including sensors, IT connections between cargo and wagons, or electronic wagon lists.

Thesis: DAC primarily benefits single-wagon transport, while combined transport and unit trains gain little or no advantage.

Jan Elfenhorst: Yes. DAC could indeed bring significant benefits to single-wagon transport, which relies heavily on efficient marshaling processes. For unit and block trains, however, which require less coupling and whose processes are already highly optimized, the advantages are limited. The importance of DAC in these areas should not be overestimated.

Ralf Jahncke: No. Limiting DAC's advantages to faster coupling processes that mainly benefit single-wagon transport is shortsighted. DAC offers clear advantages for unit trains, such as enabling train integrity tests, which are a foundation for operating with ETCS Level 3. High safety requirements for continuous integrity checks, which must be guaranteed under all conditions, can likely be better met with hardware installed on wagons than through radio connections, as hardware minimizes interference caused by environmental conditions. DAC also accelerates administrative processes, such as automatic brake testing, especially for unit trains that frequently operate as fixed shuttle units. Additionally, DAC improves driving dynamics, allowing for higher traction forces, heavier trains, reduced reliance on push locomotives, and broader utilization of modern electric locomotives’ potential, especially for Alpine transit. Electropneumatic brakes, enabled by DAC, optimize braking response and make higher freight speeds more achievable.

Thesis: Without widespread DAC implementation, the benefits of the planned European Train Control System (ETCS) will be wasted.

Jan Elfenhorst: No. The DAC is not a prerequisite for fully utilizing the potential of ETCS. ETCS enables safer and more efficient train operations and is key to harmonized rail transport across Europe. Even without widespread DAC implementation, ETCS can increase rail capacity.

Ralf Jahncke: Yes. Without on-board solutions for testing train integrity, it will likely be impossible to implement ETCS Level 3. This means valuable capacity gains would be lost or would require costly and time-consuming rail infrastructure expansions to compensate.

Thesis: ETCS makes sense but is too expensive. Without massive state funding, DAC implementation is unfeasible.

Jan Elfenhorst: Currently, no DAC implementation model exists that is self-financing. Without substantial public funding, introducing DAC would not be economically viable or competitive for many rail freight companies and their customers, especially compared to other multimodal transport options. The rail sector also faces additional costs, such as retrofitting locomotives with ETCS or higher operational costs due to infrastructure overhauls. While optimization projects are valuable, they are also extremely costly and strain the industry.

Ralf Jahncke: Yes and no. DAC risks becoming prohibitively expensive, particularly if its core functions—coupling, train integrity, and brake control—are overshadowed by attempts to integrate more and more features. For example, the originally planned 110V DC power source is now being replaced by a 400V AC source because the DC power was deemed insufficient for some applications. DAC should remain a means to an end, not a "playground" for engineers, to ensure costs stay within reasonable limits.

Thesis: Since DAC is expensive and slow to implement, its adoption should be voluntary.

Jan Elfenhorst: Yes and no. Voluntary DAC implementation could destabilize the market and undermine harmonization and standardization efforts, as differing coupling systems across Europe would lead to inefficiencies. However, companies should have the freedom to decide when and to what extent they adopt DAC, especially given the high investment costs. A master plan for all optimization projects, including detailed timelines for each, is essential to avoid overwhelming the industry, especially smaller companies.

Ralf Jahncke: No. DAC is necessary not for individual trains but for the entire rail system to function more efficiently. Partial adoption would result in duplicate structures for infrastructure and operations, such as maintaining both train-mounted integrity systems and fixed ground-based systems. Scheduling complexity would also increase, as timetables would need to accommodate both DAC-equipped and non-DAC-equipped trains, leading to inefficiencies and reduced rail capacity.

Source: Deutsche Verkehrs-zeitung