Roll-on roll-off shipping: cargo that drives aboard

Ramps replace cranes

Access is through stern, quarter or side ramps that bridge ship and quay, so the berth needs a firm marshalling area and a linkspan rather than lifting equipment. Cars, trucks, buses, agricultural and construction plant drive aboard under their own power. Anything that does not move by itself is placed on a roll trailer or cassette and pushed on by a terminal tractor, which is how static project pieces still use the method.

Deck height, ramp capacity and internal clearance decide what fits

Each deck has a fixed clear height and each ramp a maximum axle and total load. Hoistable decks let a vessel reconfigure between many low vehicles and fewer tall ones, and dedicated heavy decks carry concentrated loads that lighter decks could not bear. The binding limit is often internal clearance rather than the ramp itself, since a tall item may pass the stern opening yet foul a duct or a deckhead further inside.

Lashing wheeled cargo for a seaway

Vehicles are chocked, their brakes applied and their suspension sometimes deflated, then lashed to deck sockets with webbing or chain according to their weight and centre of gravity. A ship in a heavy swell moves in every axis, so cargo that can roll is a serious hazard. Vessels carry an approved securing arrangement, and the maritime safety framework issued by the international regulator sets out what that must cover.

Turnaround speed is the commercial heart of the trade

A vessel that can be emptied and refilled in a couple of hours can run frequent departures on a short corridor, which is what makes sea competitive with driving around a coastline. Unaccompanied working amplifies it: a tractor unit drops a trailer at the terminal and leaves, the trailer crosses alone, and another tractor collects it, so no driver time is consumed by the sea leg at all.

The trade-off against lifting

Wheeled stowage is generous with space. Vehicles need driving aisles, headroom above and clearance between them, so a RoRo deck carries less mass per unit of volume than a hold packed with containers. That makes the method expensive for dense cargo and excellent for anything self-propelled, awkwardly shaped, or too valuable to be craned.

Frequently asked questions

Can cargo that has no wheels still travel roll-on roll-off?

Yes. It is loaded onto a low roll trailer or cassette at the terminal and manoeuvred aboard by a terminal tractor, then left on that platform for the voyage. This is common for project pieces and awkward machinery.

What is unaccompanied trailer traffic?

A trailer that crosses without its tractor unit or driver. It is delivered to the terminal, shunted aboard, and collected on the other side by a different unit, which keeps driver hours from being consumed by the sea passage.