This project explores the prospects for interior design in a dual purpose train that can run both day and night for improved utilization and comfort. Contemporary trains are categorized as either exclusively for daytime or nighttime use. Their interiors limit them to specific temporal contexts. For instance, in daytime trains, passengers are confined to sitting positions and cannot lie flat, resulting in suboptimal sleeping comfort. Thereby the appeal of such trains for night (long distance) travel is reduced. Conversely, in existing night trains, while passengers can lie flat, the fixed layout featuring compartments and beds makes the capacity of the train too low for daytime use. Moreover, night trains face strong competition from aviation, rendering their utilization challenging. A solution to this problem involves designing a train interior that serves the dual purpose of accommodating both daytime and nighttime travel. Drawing insights from research, and the existing coach geometry, four distinct design directions were developed. Emphasis was placed on striking a balance between coach capacity and passenger comfort, recognizing the inherent tension between these two factors in this context. One of these directions was further refined into the final concept. In refining the final concept, the emphasis was on creating a passenger experience characterised by privacy, safety and comfort. Two Virtual Reality tests were conducted among other efforts to achieve this goal. The final concept features a symmetrical coach with a centrally positioned entrance. The entrance aligns with the platform's height, facilitating easy boarding for passengers with reduced mobility. The central hall houses a self-service bar for acquiring food and beverages. Adjacent to the central hall are seats on both sides. During the day, passengers can occupy these seats, which are configured in sets of two facing each other. No ticket reservation is necessary for daytime travel, and the coach accommodates 72 passengers during this period. Capacity is thereby 10% lower than in daytime-only trains. At night, the seats transform into beds, offering passengers the option to lie flat. Privacy screens can be easily placed around the bed, and overhead lockers are available for secure luggage storage. The nighttime capacity is 36 passengers, which is the same capacity as the sleeper accommodation in night trains. Ticket reservation is obligatory for overnight travel. The coach incorporates two toilets and two washrooms. Distinct zones within the coach, such as a quiet zone, a socializing zone, and a women only zone for nighttime travel, contribute to a tailored and comfortable passenger experience.