Freight containers, also known as shipping containers, are standardized enclosures with typical dimensions of 20’x8’x8.5′, 40’x8’x8.5′, or 45’x8’x9.5′. These containers are built to withstand the stresses of long ocean voyages and transfers between different modes of transport. To ensure safety and reliability in international shipping, they must meet certain minimum sturdiness standards and obtain CSC (Convention for Safe Containers) certification. Specialized trucks, railcars, and handling equipment are designed to accommodate these standardized containers. Their uniform size allows them to fit efficiently into these vehicles and ships’ cargo holds. Handling equipment facilitates easy transfer between trucks, railcars, and ships. Many containers, especially those 20 feet or shorter, feature forklift pockets for easier handling.
Standardized freight containers have greatly increased the speed and efficiency of cargo movement, boosting global trade. The ease and speed of transferring containers between different modes of transport, known as intermodal transport, is a key factor in this efficiency. This multi-modal capability enables goods to be transported seamlessly across various terrains like water, rail, road, and even air, from origin to destination without interruption.
Freight containers are commonly transported on “cellular” container ships. The cargo area of these ships is divided into standard cells designed to hold containers, resembling a honeycomb structure. A ship’s cargo capacity is measured in TEUs (twenty-foot equivalent units). One TEU represents the space occupied by a 20-foot standard freight container, while a 40-foot container occupies 2 TEUs. Modern container ships can carry close to 5000 TEUs.
Freight containers are designed to be vandal-resistant, incorporating robust locking mechanisms. Typically, they feature a double door secured by four locking bars that run the entire height of the container. These locking bars include lockable handles that can be further secured with padlocks and seals. Enhancing security involves packing and locking the container at the shipper’s location and only opening it at the consignee’s premises. Any necessary customs inspections and certifications are carried out at these locations. Due to these security features, container-based shipments often have lower insurance costs for theft, pilferage, and damage.
Effective packing of freight containers requires careful planning. Cartons often come in irregular sizes, and the internal dimensions of containers are smaller than their external dimensions. Therefore, simply dividing the outer volume of a container by the volume of a carton will not give an accurate estimate of the number of cartons that can be packed. For example, a 20’x8’x8.5′ container has an outer volume of 1360 cubic feet. Dividing this by the volume of a 1.5’x1’x1′ carton (1.5 cubic feet) might suggest that 906 cartons can be packed into the container, which is misleading. The internal dimensions of a 20-foot container are approximately 19.35’x7.71’x7.83′, giving an internal volume of 1168 cubic feet. Dividing this volume by the carton volume of 1.5 cubic feet gives 778. However, even this figure is incorrect because of the carton’s dimensions. Efficient planning is key to maximizing the use of space inside a freight container.