DLR Unveils ALISA Concept for Lightweight European Night Trains
The German Aerospace Center (DLR) presented a new concept for European night train travel on September 22 at InnoTrans 2026, the international transport technology trade fair in Berlin. The concept was developed under the ALISA research project together with rail industry partners TRICON, GETA, satek and k+v.
ALISA stands for "Angebotsdifferenziertes, leichtes und innovatives Schlafwagenkonzept" - in English, "service-differentiated, lightweight and innovative sleeping car concept." The DLR Institute of Vehicle Concepts led the project's technical work, aiming to combine high comfort and privacy for passengers with high capacity, flexible use and economical operation. The centerpiece of the design is a lightweight, optimized unit made up of three fixed-coupled double-decker carriages with a total length of approximately 46 meters. The project was funded by Germany's Federal Ministry for Economic Affairs and Energy (BMWE).
Night trains have been gaining popularity across European long-distance rail travel, driven by climate and environmental concerns alongside a desire for travel time that can be used more productively than time spent driving or flying. That rising demand comes with higher expectations, particularly for interior design, as passengers want more space, comfort and privacy. To keep operations cost-effective, rolling stock has to carry as many passengers as possible on frequent services. Traditional sleeper and couchette carriages were built primarily for nighttime use and stood idle during the day.
"To meet all these requirements, we at ALISA have viewed the night train as a complete system. Using lightweight construction and digital development methods, we have designed and optimised the vehicle structure accordingly. In doing so, we have laid the technical foundations for a night train that is both attractive to passengers and efficient to operate," said Nicolai Schmauder, who led the project for DLR.
The basic ALISA unit consists of three fixed-coupled double-decker carriages, with both levels fully walk-through. That gain in space and accessibility is made possible by mechatronic single-wheel rail running gear developed and tested at DLR. Multiple basic units can be coupled together, allowing train length to be adjusted based on route, demand and season. Within each carriage, standardized segments allow different interior configurations without requiring a new carriage body design for every variant. The interior concept spans a range of needs and price points, from classic seats and reclining sleeper chairs to private single and double cabins and larger compartments for families and passengers with reduced mobility.
A double-decker design combined with high passenger capacity and comfort expectations can sharply increase carriage weight, so a central focus of DLR's work was developing as lightweight a vehicle concept as possible. DLR researchers optimized the carriage body so the vehicle structure distributes and absorbs acting loads and forces as efficiently as possible, reinforcing areas that need to withstand high forces while lightening less heavily loaded sections. As part of this "functional integration" approach, the team investigated how cable ducts and interior fittings could be built directly into the load-bearing structure, avoiding added weight without reducing usable interior space.
Further weight savings came from multi-material construction methods, including sandwich materials that combine an outer aluminum layer with a wood or aluminum honeycomb core for a structure that is both lightweight and stable. "With our consistent lightweight-construction approach, we can increase passenger capacity by 40 percent with no increase in axle load, while passengers don't have to compromise on comfort or privacy. Our reference was the latest generation of the 'Nightjet' night train, operated by Austrian Federal Railways (OBB)," Schmauder said.
The TRICON design agency developed the interior concept, accounting for different travel needs and comfort levels. Folding and conversion mechanisms allow sleeper cabins to convert into seating areas during the day, meaning the same train could serve both overnight and daytime routes. During concept development, the ALISA team explored spatial layouts using virtual reality and full-scale models. GETA and satek, specialists in rail interiors and sanitary facilities respectively, contributed their expertise, while DLR worked with k+v Ingenieurgesellschaft to develop and optimize the load-bearing vehicle structure. "This close collaboration and the expertise of everyone involved in the rail sector were a key factor for the success of the ALISA project. This allowed us to coordinate the interior, carriage body, materials and technical equipment from the outset, and bring them together into a concept for a complete vehicle," Schmauder said.
Through September 25, the project team is presenting the ALISA concept and its structural development at InnoTrans, with a 1:10 scale model of the complete three-carriage train and full-scale walk-through sections of selected compartments. A VR application also allows visitors a virtual look inside the interior and carriage body.
CONTACT: https://www.dlr.de/en/fk
