Bi-level trains, also known as double-decker trains, feature two levels of seating for passengers. This design allows for increased capacity, accommodating more travelers without requiring additional train cars. They are commonly used in commuter rail services and long-distance routes, providing a comfortable travel experience. These trains are equipped with staircases or elevators for easy access between the two levels. Bi-level trains are popular in regions with high passenger demand, such as North America and Europe, where they help reduce congestion and improve efficiency in public transportation systems.