Dimensions, types and loading of containers

The development of maritime transport has contributed to the increased popularity of containers. Nowadays they constitute a key element of international transport, owing to the standardisation of dimensions and the creation of numerous types of containers, which allow for the carriage of different types of loads.

Containers are mostly used in intermodal transport thanks to their standardised construction, which enables transhipment without interfering with the interior of the container. The same unit can be used for transport by ship, train and truck, which makes them a clear advantage.

Most often, however, containers are used in maritime transport, mainly because of its greatest potential. The world’s largest container ship in 2022 could carry over 24,000 of them, while an electric barge (PortLiner EC 350) can only accommodate 350, a medium-length cargo train (up to 650m) – 84 and a truck – 2 units.

The use of containers also has some disadvantages – transport by ship usually takes much more time than by other means of transport, especially when combined with weather conditions – storms, typhoons, hurricanes – which can cause delays on the route. Furthermore, despite the container’s high load capacity, it is not always possible to make full use of it, due to road restrictions, for example.

Types of sea containers and their purpose

Containers are divided depending on their intended use, i.e. the type or quantity of the load they carry, as well as on their loading capacity. The most standard ones are those loaded through doors, but if required, the goods can be loaded through the roof, from the sides, or even through the side and the roof. Usually each type is available in two sizes – 20 and 40ft containers.

The most popular types of containers:

1. General purpose containers

The most common type of a sea container, used mainly for the transport of general cargo. The door is placed on one of the walls. The tare weight of a container, i.e. the empty weight of the container, depending on its size, is 2-3.5 tonnes. The maximum payload varies and depends on the technical requirements and arrangements with the carrier, as well as whether it is a 40 or 20ft container.

General purpose containers can also be divided into:

• open sided containers, i.e. containers with open sides;
• open top and hard top container, which do not have a roof. They are mostly used for the transport of loose goods and for loads exceeding the height of the container. Lack of the roof allows goods to be loaded from the top, which is particularly useful for cargo that is difficult to load through limited doors. However, they are significantly more expensive than standard containers.

2. Tank containers

Round containers, designed for the transport of liquid or gaseous materials such as fuel or milk. The cylindrical tank is usually fitted into a metal frame, the dimensions of which are similar to those of a 20ft container. This type of container can hold around 20,000 litres and is normally filled at 80%.

3. Thermal containers

They contain a built-in fridge and walls reinforced with thermal insulation that allows the temperature to remain positive or negative at all times. These containers are typically used for storing food or medicine.

4. Bulk containers

They can be used to transport dry bulk goods. Although their dimensions are similar to those of standard containers, they are distinguished by additional elements facilitating loading and unloading of goods, such as round openings placed on the roof.

5.  Flat rack and platform containers

They are ideal for transporting goods that are heavy or exceed the width of the container, as well as oversized cargo. Flat rack containers have a dedicated floor, front and rear to allow loading from the side or top. They are strengthened so that the goods can be transported safely. Platform containers, on the other hand, only have a floor and are used for transporting very heavy loads. 

6. Named cargo containers

They are used to transport specialised loads such as live animals or cars.

Additionally, there are less common types of containers, such as dry bulk containers or ventilated containers.

Container dimensions

Loading of a shipping container

The type of a container generally defines the type of goods it carries. Most of the time goods in containers are transported on euro or industrial pallets, just like in road transport. Depending on the arrangement, a 20ft container can accommodate 11 euro pallets, while a 40ft container can accommodate 24 or 25 euro pallets. In comparison, a standard semi-trailer holds 33 to 34 pallets.

Loading of a container, like any other cargo space, must be done in such a way as not to damage goods or the space. Goods in containers must be distributed in such a way that the amount of empty space is kept to a minimum. The filler should be placed in the empty spaces to prevent the goods from moving in the container. 

When planning the loading, the internal dimensions of the container as well as the size of the doors are taken into account. These are key parameters for determining the maximum quantity and size of cargo that can be loaded into a container. 

When a container is loaded, particular attention is paid to the weight of the cargo so as not to exceed the permissible total weight. The goods should be evenly distributed over the entire floor area. It should not press against the container door. If the unit is also to be used for road transport, it must be checked that its weight does not exceed the permitted standards for the roads on which the truck will be travelling.

Container loading software

It is worth planning the loading of the container in advance so that all the necessary parameters are considered. This is made possible by Goodloading, an application in which a detailed loading plan can be prepared. Above all, you can quickly see how best to distribute the loads on the containers, taking capacity or loading sequence into account. 

The first thing to do in the application is choosing a loading area. When adding a container to the application, in addition to indicating its dimensions, the loading method is set – from the back, from the right, from the left or from above. It is possible to set the center of gravity, so that the cargo is stable during transport. For refrigerated containers, it is possible to indicate the dimensions of the aggregate, which allows you to plan the loading of the container with this element in mind. The last point is the doors, it is possible to indicate their length and width which allows you to take them into account when loading, avoiding costly mistakes.

If you do not know which container is best for you, you can first add loads and then use the space recommended by the application’s algorithm. Then, add the loads manually by entering their dimensions, or by importing a csv file from the Excel application. The prepared arrangement is shown on a 3D visualisation with the possibility of manual reallocation of selected loads. 

Goodloading acts as a calculator for loading containers, because under the visualisation there is a loading summary with all the necessary information such as: the number of loaded and unloaded goods, total weight, volume and surface area in square metres. This provides the planner with all the data in one place, without the need to make traditional calculations.

The finished project can be sent to the person responsible for loading in the form of a link or PDF file including the loading sequence, or exported as a csv file that can be opened in a spreadsheet.