Introduction
A multi-trailer system (MTS) allows transportation of a larger number of containers as opposed to the traditional single trailer systems. Therefore terminal and port operators consider the MTS as one of the options for increasing efficiency.
In the 1980s operators around the world started experiments with MTSs operating between ship and container stacks, and between different container yards (or terminals).
In the ‘inter-yard’ mode containers are transported a few kilometres and a MTS is made up of a large number of trailers (from four to seven). Usually, after transporting a trailer set to the destination exchange area, the tractor disconnects from one set and connects to another one, which is ready to be moved back. Thus one tractor handles multiple trailer sets and trailer sets are used as buffers.
In the ‘ship to stacks’ mode, the MTS transports containers from/to the wharf during vessel operations. In this mode, tractors usually remain connected to the same trailer set.
Nowadays most MTSs are used in ‘inter yard’ mode. However, the topic of using a MTS for ship to stacks transport is still alive. Recently a number of European operators have begun implementing the MTS (two or three trailers in a set) for the short distance ship to stacks transportation in high-density terminals.
Certainly, this option is always considered when a wharf is located offshore and long distance transport to container stacks is required. The following paper suggests a new approach for planning a number of MTS vehicles in the ship to stacks operation, and provides Strengths, Weaknesses, Opportunities and Threats (SWOT Analysis) of using a MTS for ship to stacks transportation, as well as discussing options for improving each weakness and exploiting and benefiting from opportunities.
Equipment options
The following options are available at present: Semi-trailer Lead MTS (Short MTS) A short MTS is made up of a tractor, a lead single axle semitrailer and one or two drawbar trailers. The tractor is connected to the lead semi-trailer using a fifth-wheel. During an operation, the trailer set can change its size from one to three trailers, but the tractor remains connected to the same semi-trailer.
Drawbar-trailer Lead MTS (Long MTS)
A drawbar-trailer Lead MTS is the system made up of several drawbar trailers (maximum seven), pulled by a ballasted heavyduty terminal tractor. The tractor can quickly connect to the first drawbar trailer, using either automatic or manual coupling. The trailer set in a Long MTS remains intact.
Bidirectional MTS
A bidirectional MTS consist of tractor and multiple drawbar trailers with the drawbars installed on both sides, so the tractor can be connected on either side. A bidirectional MTS can change moving direction without turning around. The feature is beneficial for congested and narrow areas, for instance narrow quays, where turning around is not possible. Bidirectional MTSs are currently in the experimental phase.
