A new double-deck night-train concept developed by Germany’s DLR and rail industry partners aims to combine greater privacy and comfort with higher capacity and more efficient operation. Full-scale mock-ups of the ALISA concept are being presented at InnoTrans 2026 in Berlin.
The German Aerospace Centre or Deutsche Zentrum für Luft- und Raumfahrt (DLR) and a group of rail industry partners have presented a new concept for Europe’s night trains, designed to address one of the sector’s biggest challenges: how to offer passengers more space, comfort and privacy while keeping overnight services economically viable.
The ALISA project – short for Angebotsdifferenziertes, leichtes und innovatives Schlafwagenkonzept, or ‘service-differentiated, lightweight and innovative sleeping car concept‘ – was developed by DLR together with design agency TRICON, rail interiors specialist GETA, sanitary systems company satek and engineering firm k+v. The project was funded by Germany’s Federal Ministry for Economic Affairs and Energy.
The concept is being presented at InnoTrans 2026 in Berlin, including a 1:10 scale model of the complete train and full-scale, walk-through sections of selected compartments.
Rethinking the night train
ALISA starts from the premise that the traditional night train needs to do more than simply provide beds.
Demand for overnight rail travel is growing again in Europe, while passengers increasingly expect space, comfort and privacy. At the same time, operators need trains with high capacity and good utilisation if services are to be economically sustainable.
Traditional sleeping and couchette cars also tend to be designed primarily for overnight operation, leaving expensive rolling stock underused during the daytime.
“To meet all these requirements, we at ALISA have viewed the night train as a complete system,” said Nicolai Schmauder, who led the project for DLR. “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.”
The result is a modular train concept based around three permanently coupled double-deck coaches, with a total length of approximately 46 metres.
From seats to private cabins
The ALISA interior is designed to cover a wide range of passenger needs and price points.
Operators could choose from conventional seating and reclining sleeper chairs to private single and double cabins. Larger compartments for families and passengers with reduced mobility are also part of the concept.
The aim is to bridge the traditional divide between seating cars, couchettes and sleeping cars by offering more intermediate accommodation types.
A three-car ALISA unit could accommodate 84 sleeping passengers or 106 seated passengers, with various configurations possible between those two extremes.
The interiors are modular, with standardised sections allowing the layout to be adapted to different operators, routes and passenger demand without requiring a completely new vehicle body.
Several three-car units could also be coupled together, allowing train length to be adjusted according to the route, season or expected demand.
Double-deck design without sacrificing accessibility
Double-deck trains can offer significantly more capacity, but fitting passenger accommodation, equipment and technical systems into a compact vehicle creates major engineering challenges.
ALISA addresses this partly through single-wheel running gear developed and tested by DLR. This allows both levels of the train to be fully walk-through and improves accessibility throughout the unit.
The three-car set is around 46 metres long, with each coach body measuring approximately 14 metres. The short vehicle bodies provide around 5% more interior width than more conventional vehicles, while using the GC clearance profile could provide a further 15% in volume.
Each vehicle is divided into standardised 2.55-metre sections. This modular structure is intended to make it possible to adapt the interior to different requirements without developing a new vehicle body or technical interfaces for every configuration.
Lightweight construction is key
Keeping the double-deck vehicle light was one of the central challenges of the ALISA project.
DLR used topology optimisation to calculate how loads and forces are distributed through the vehicle structure. Areas subject to particularly high forces can therefore be reinforced, while less heavily loaded sections can be made lighter.
The project also investigated so-called functional integration, in which elements such as cable ducts and interior fittings can be incorporated directly into the load-bearing structure. This reduces weight without taking away usable passenger space.
Further weight savings come from multi-material construction, including sandwich structures combining aluminium outer layers with lightweight honeycomb cores.
“With our consistent lightweight-construction approach, we can increase passenger capacity by 40% with no increase in axle load, while passengers don’t have to compromise on comfort or privacy,” Schmauder said. “Our reference was the latest generation of the Nightjet night train, operated by Austrian Federal Railways (ÖBB).”
The project also incorporates diagonal structural elements, including 45-degree window struts, to distribute loads efficiently.
A train for day and night
Another central feature of ALISA is that its accommodation does not necessarily have to remain in sleeping configuration throughout the day.
Folding and conversion mechanisms allow sleeping cabins to be transformed into seating areas. This could enable the same train to operate daytime and overnight services, increasing rolling-stock utilisation.
That is particularly important because one of the fundamental challenges facing night trains is that expensive vehicles can spend much of the day unused.
ALISA therefore seeks to improve the economics of overnight rail not simply by carrying more passengers, but by making the train useful for more hours of the day.
TRICON developed the interior concept, while GETA and satek contributed expertise in rail interiors and sanitary facilities. DLR worked with k+v on the vehicle structure and its optimisation.
“This close collaboration and the expertise of everyone involved in the rail sector were a key factor for the success of the ALISA project,” Schmauder said. “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.”
The team used virtual reality and full-scale models during the development process to test and refine different layouts.
Ten years from idea to concept
The ALISA concept has been in development for around a decade.
Project initiator Olaf Schulz, who works in railway operations, originally conceived the idea as a response to the financial difficulties faced by night-train operators. He first developed the concept around 10 years ago, while industrial design company TRICON became involved around five years later.
The formal ALISA research project began three years ago. Schulz was nominated for a RailTech Innovation Award in 2022 and presented the concept at RailTech Europe in Utrecht that year.
The project has now reached the end of its research phase.
“Now that the research project is finished, we hope that we can find companies to make it a reality,” Schulz told Railway Gazette International.
The biggest obstacle during the project’s development was not necessarily the technology, Schulz said, but regulation.
“The biggest challenge were all the regulations. But in the end, everything is according to the regulations, and ready to be implemented.”
That leaves ALISA at an important crossroads. The concept has been engineered, modelled and presented at full scale, but it still needs an industrial partner willing to turn the research project into an actual train.
From concept to commercial train
ALISA is therefore not yet a new night-train service, nor has a launch date or operator been announced.
Its significance lies instead in the questions it is trying to answer. Can double-deck rolling stock provide the capacity needed to make night trains more viable? Can modular interiors offer passengers a much wider choice between seats, reclining accommodation and private cabins? And can the same vehicles earn revenue during both the day and night?
Those questions are becoming increasingly important as Europe attempts to revive its night-train network.
For now, ALISA remains a concept. But with full-scale mock-ups now on display and the research phase completed, its developers are hoping the next step will be turning an ambitious research project into a real European night train.
