RORO
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Loading a Ro Ro passenger car ferry |
RORO and
ro-ro are
acronyms for
Roll On/Roll Off, describing a significant feature of a
ship designed to carry wheeled cargo such as automobiles, trailers or railway carriages. RORO vessels have built-in ramps which allow the cargo to be efficiently "rolled on" and "rolled off" the vessel when in port. This is in contrast to
lo-lo (lift on-lift off) vessels which use a
crane to load and unload cargo.Various types of RORO vessels include
ferries,
cruiseferries, cargo
ships, and
barges. A true RoRo's ramps can serve all of the vessel's decks; otherwise it is a hybrid type (see below).
Unlike elsewhere in the shipping industry where cargo is normally measured by the Metric Ton, RoRo cargo will typically be measured in the more convenient unit of Lanes In Metres (LIMs). This is calculated by multiplying cargo length in metres by its width in lanes. (Lane width differs from vessel to vessel and there are a number of industry standards.)
While smaller ferries that operate across
rivers and other short distances often have built-in ramps, the term RORO is generally reserved for larger ocean-going vessels.
New automobiles that are transported by ship around the world are often moved on a large type of RORO called a Pure Car Carriers (PCC) or Pure Car Truck Carriers (PCTC).
The largest RORO barges in the world operate between the
United States and
Puerto Rico carrying highway trailers, shipping containers on chassis, new and used cars, and oversized cargos on three decks. These barges are towed by ocean-going
tugs and sail four times per week from
Jacksonville, Florida to
San Juan.
At first, wheeled vehicles carried as cargo on oceangoing ships were treated like any other cargo.Automobiles had their gas tanks emptied and their batteries disconnected before being hoisted into the ship's hold, where they were chocked and secured. This process was tedious and difficult, and could not be used for routine travel.
The first RoRo ships were ferries carrying steam trains across rivers. One of the earliest was
Firth of Forth ferry in Scotland which started in 1851 and operated for nearly forty years, until the completion of the
Forth Bridge.
During WWII,
landing craft were the first ships enabling road vehicles to roll directly on and off. Post war, the idea was adopted for merchant ships and short ferry crossings. The first RoRo service crossing the English channel began from
Dover in
1953.
In
1957 the US military issued a contract to the Sun Shipbuilding and Dry Dock Company in Chester, PA for the construction of a new type of motorized vehicle carrier. The ship,
Comet, had a stern ramp as well as interior ramps which allowed cars to drive directly from the dock, onto the ship, and into place. Loading and unloading was speeded dramatically. Comet also had an adjustable chocking system for locking cars onto the decks, and a ventilation system to remove any exhaust gases that accumulated during vehicle loading.
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A PCC ship's starboard side showing side ramp. |
Since 1970 the market for exporting and importing cars has increased dramatically and the number and type of RO/ROs has increased also. In 1973, Japan's
K Line built the
European Highway, the first Pure Car Carrier, which carried 4,200 automobiles. Today's pure car carriers (and their close cousins, the Pure Car/Truck Carrier) are distinctive looking ships with a box-like superstructure running the entire length and breadth of the hull, fully enclosing and protecting the cargo. They typically have a stern ramp and a side ramp for dual loading of many thousands of vehicles, as well as extensive automatic fire control systems. The largest PCC currently in service is the
MV Mignon, which can carry up to 7,200 cars.
The seagoing RORO car ferry, with large external doors close to the waterline and open vehicle decks with few internal
bulkheads, has a reputation for being a high risk design. An improperly-secured loading door can cause a ship to take on water and sink, as happened for example with the
Herald of Free Enterprise in
1987. Also, water sloshing on the vehicle deck can set up a
free surface effect making the ship unstable and causing it to
capsize.
(On the other hand, the car carrier
Cougar Ace listed 80 degrees to its port side in 2006 but did not sink, since its high enclosed sides prevented water from entering.)
The acronym
ROPAX describes a RORO vessel equipped with
cabins to accommodate passengers.
The
ConRo vessel is a hybrid between a RORO and a
container ship. This type of vessel has a below-decks area used for vehicle storage while stacking
containerized freight on the top decks.
A
RoLo vessel is another hybrid vessel type with ramps serving vehicle decks but with other cargo decks accessible only by crane.
*
List of RORO vessel accidents*
IMO and ro-ro safety*
Ro-Ro shipping rates and online consumer guide
