This study deals with sustainability issues in transport, focusing on rail and air transport. The background to the research is the need to reduce the carbon footprint of transport, which includes prioritising rail. The current developments in the world: the rise of climate protection and sustainability, increasingly environmentally conscious lifestyles, and the growing media attention on these issues (including Greta Thunberg's activity) suggest that long-distance environmental friendly vehicles like overnight rail passenger trains is likely more to use in Europe. This makes it necessary to improve the rail services. However, previous studies have dealt separately with the environmental issues and the railway development. That is why the scope of the research is to link these two separate topics. In order to achieve the future objectives of the (night) rail market, it is necessary to define what can be meant by rail sustainability, so that the environmental friendliness of this transport mode can be clearly expressed to the public. Therefore, the aim of this research is to determine the relationship between the less polluting rail sub-sector and sustainability by analysing night rail travel compared to short-haul air travel. As a result, the definition of sustainability in rail transport and a case study with the practice of product design methodologies that increase the role of the railway are presented. With the rise of the (night) rail transport, fewer flights will be needed.