Ro-ro ships are also called "open top and open bottom" ships, or "ro-ro-ro" ships. It is a special ship that uses freight vehicles to carry goods, and tractors to tow semi-trailers or wheeled pallets to carry boxes or other goods directly into and out of the cargo hold for loading and unloading.
Ro-ro ship is developed on the basis of car ferry. After World War II, Britain opened a regular route to Hamburg, Germany with a retired landing craft, and vehicles loaded with goods could land directly. Although landing craft transportation is uneconomical and has no promotion value, it is an epoch-making event in the history of transportation, because it has created a new form of marine transportation-ro-ro transportation.