Movement of Containers

Movement by Highway

Marine container volumes are growing with the unprecedented increase in foreign trade. While containers on chassis constitute a small proportion of heavy truck traffic nationally, containers account for a high percentage of truck traffic on highways around major ports. Domestic use of containers is also increasing in popularity, although at a lesser rate than international shipments.

Movement by Rail

The ISO containers can be moved by rail on all broad gauge systems. Wagons used in this type of application include both tailor-made wagons designed to handle containers only as well as multi-purpose wagons.

 Due to differences in loading gauges and operating practices, the equipment used to move containers in North America and Europe is quite different. Only some North American routes have sufficient clearances to handle stacked containers i.e. one on top of the other in ‘well cars’. These wagons are called “well cars” because the center into which the bottom container(s) fit(s) is below the top of the wheels.

 The movement of containers by train is a growth movement in all parts of the world. Overall it is quicker and cheaper compared to road subject to movement being in complete train formation on a regular scheduled basis and thereby attaining good infrastructure utilization.

Movement by Vessel

Standardized containers are transported by container ships and they are used to transport any kind of cargo all over the world. The dimension of the ships depends on the number of containers that it is supposed to carry with. The measurement unit for transport capacity used is TEU (Twenty feet Equivalent Unit), that is a 20 feet container is equivalent to 1 TEU and a 40 feet container is equivalent to 2 TEU. The vessel is assumed to be a simple rigid and flexible beam in which the waves of the sea act and create stresses that produce bending of the vessel; this is known as hogging and sagging.

Despite the changing production and world trade, the maritime transport has continually grown for the last decades. This growth has been suffered specially by container ships. The use of containers growth is shown by the nowadays construction of bigger ships, reaching some of them 16000 TEUs.

This advance is directly related to the growth of the developing countries, especially in Asia and South America and the tendency to globalization of the multinational manufacturing companies with at the same time improvement of the marine structures, giving the possibility and necessity of the construction of bigger container ships.

The international structural commercial changes and the evolution of the marine transport directly affect the development and expansion of harbours. Therefore, it is essential to analyse these aspects and its recent characteristics, because they show the reference beyond which the development of the harbours are being done.

These changes are hardly being affected by the development of the containers transports, This huge development of the container transport has to be done by the hand of a security in the transport and manipulation. This issue is bigger as long as the ships have a higher transport capability, so the control and resistance tests should be done with the greater precision as possible.

Therefore, the commercial opportunities that the containers transport gives are a really big challenge to the marine structural engineers. The future of container ship development is promising.

Transfer of Containers (Terminals)

At container terminals, containers are transshipped from one mode of transportation to another. Within terminal different types of material handling equipment are used to transship containers from ships to barges, trucks and trains and vice versa.

Over the past decades, ships have significantly increased in size, up to 8000 TEU (Twenty feet equivalent unit container). In order to use these big ships efficiently, the docking time at the port must be as small as possible.

This means that large amounts of containers have to be loaded, unloaded and transhipped in a short time span, with a minimum use of expensive equipment.

Interchange of Containers

In recent years the container leasing industry has been shifting towards long-term leasing, primarily 5-year contracts. Under a long-term lease, a liner shipping company can have a direct interchange of empty containers with other transport carriers.

Direct interchange is an item that appears in standard leasing terms and conditions. With direct interchange a lessee may direct interchange of containers with a third party provided that each direct interchange is preapproved in writing by the lessor. The lessee will charge a direct interchange fee as the agreement. Liner shipping companies can access an Internet-based SynchroBox system to review and select container interchange in a real-time on-line environment.