Roll-on/roll-off ships are cargo ships designed specifically to transport wheeled cargo, such as cars, motorcycles, trucks, semi-trailer trucks, buses, trailers and railroad cars, which are moved directly onto and off the ship by their own wheels or on a platform vehicle such as a self-propelled modular transporter. This is in contrast to lift-on/lift-off (LoLo) vessels, which rely on cranes to load and unload cargo.