Intermodal Services

Types of Intermodal Containers

Although intermodal containers were standardized by the International Standards Organization (ISO) in 1961, there are still many types and sizes that exist for various shipping purposes.

These containers are classified according to their intended purpose regardless of whether they are new or being re-used. To ensure durability and security, most containers are constructed from aluminum or steel and manufactured to ISO specifications.

The most common sizes of intermodal containers are 20, 40 and 45-feet in length. Companies that offer intermodal services typically have containers that fall into two categories; general purpose and specific purpose.

General Purpose Containers

The most common types of general purpose containers include:

  • Dry cargo
  • Special dry cargo
  • Open top
  • Flat rack
  • Closed ventilated

Dry Cargo

Dry cargo is the most common type of container and is used by almost every intermodal services provider across the globe. Constructed from steel, these containers are encased with strong and rigid walls, roofs and floors that are resistant to the environmental elements. The standard lengths are 20 and 40-feet with an 8-foot width.

Special Dry Cargo

In some instances, the loading and unloading of cargo cannot fit through the end or side doors so special dry cargo containers must be used. These include; open top, flat rack and closed ventilated containers.

Open Top

Open top containers boast the same characteristics as dry cargo boxes with the exception of the roof. Typically, durable canvas is used to protect the cargo. The canvas is placed on special roof bows to secure it. This container is usually utilized for fragile, bulky or heavy items.

Flat Rack

The flat rack is another option but does not have the same enclosed structure with fixed walls. Instead, are a floor and two end walls with special corner fittings at the top and bottom of the container to guarantee safe stacking. These containers are most commonly used to transport wood and other difficult objects.

Closed Ventilated

Closed ventilated containers are the third types created for special cargo. This type of container used by intermodal services companies protects against excessive humidity with the special ventilation equipment within the box.

Specific Purpose Containers

The most frequently used special purpose containers include:

  • Thermal
  • Insulated
  • Refrigerated
  • Mechanically refrigerated
  • Heated
  • Dry bulk
  • Tanks


Also known as reefers, thermal containers are constructed from interior insulation on all sides of the box. This type of container is used by intermodal services firms to prolong food shelf-life and perishable goods. These containers restrict the temperature range throughout the container and can be found in the standard 20 and 40-foot options.


One of the most popular types of reefers (refrigerated containers) is the insulated container which does not require temperature regulation. Instead, the internal insulation maintains an ambient temperature.


Refrigerated containers hold cold temperatures through insulation and dry ice or liquefied gas. These types of boxes used during intermodal services do not have an external power source to refrigerate the cargo.

Mechanically Refrigerated

On the other hand, mechanically refrigerated containers have a power supply similar to a home refrigerator. The power supply is provided to intermodal services organizations at seaports or on road distribution networks to attach to an existing refrigerated container.


Similarly, heated containers utilize a power supply to run a heat-producing device.

Dry Bulk

Dry bulk containers are used for products that contain tertiary packaging. For instance, grains and dry foodstuffs use dry bulk shipping containers.


Finally, tank containers are specially-constructed boxes that transport tanks which hold chemicals, gases and a variety of other hazardous materials.

For detailed information, maps and contact information for the ports of Los Angeles and Long Beach, be sure to download a free copy of our Comprehensive Port Service Guide.