Roll-on/roll-off (RORO or ro-ro) ships are cargo ships designed to carry wheeled cargo, such as cars, motorcycles, trucks, semi-trailer trucks, buses, trailers, and railroad cars, that are driven on and off the ship on their own wheels or using a platform vehicle, such as a self-propelled modular transporter. This is in contrast to lift-on/lift-off (LoLo) vessels, which use a crane to load and unload cargo. RORO vessels have either built-in or shore-based ramps or ferry slips that allow the cargo to be efficiently rolled on and off the vessel when in port. While smaller ferries that operate across rivers and other short distances often have built-in ramps, the term RORO is generally reserved for large seafaring vessels. The ramps and doors may be located in the stern, bow, or sides, or any combination thereof. Description Types of RORO vessels include ferries, cruiseferries, cargo ships, barges, and RoRo service for air deliveries. New automobiles that are transported by ship are often moved on a large type of RORO called a pure car carrier (PCC) or pure car/truck carrier (PCTC). Elsewhere in the shipping industry, cargo is normally measured by the tonne, but RORO cargo is typically measured in lanes in metres (LIMs). This is calculated by multiplying the cargo length in metres by the number of decks and by its width in lanes (lane width differs from vessel to vessel, and there are several industry standards). On PCCs, cargo capacity is often measured in RT or RT43 units (based on a 1966 Toyota Corona, the first mass-produced car to be shipped in specialised car-carriers and used as the basis of RORO vessel size. 1 RT is approximately 4m of lane space required to store a 1.5m wide Toyota Corona) or in car-equivalent units (CEU). The largest RORO passenger ferry is , a 75,100 GT cruise ferry that entered service in September 2007 for Color Line. Built in Finland by Aker Finnyards, it is long and wide, and can carry 550 cars, or 1270 lane meters of cargo. The RORO passenger ferry with the greatest car-carrying capacity is Ulysses (named after a novel by James Joyce), owned by Irish Ferries. Ulysses entered service on 25 March 2001 and operates between Dublin and Holyhead. The 50,938 GT ship is long and wide, and can carry 1342 cars/4101 lane meters of cargo. Car carriers The first cargo ships specially fitted for the transport of