Intermodal container

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A 40-foot (12.19 m) long shipping container. Each of the eight corners has a simple twistlock fitting for stacking, locking and hoisting
There are over seventeen million shipping containers in the world
Containers on rails in Jyväskylä, Finland
Containers standing with their loading doors open
Stacking shipping containers each with a standard ISO 6346 reporting mark
Corner casting on a shipping container. The twistlock proper is done through a larger oval hole on the bottom.

An intermodal container (also known as a container, freight container, ISO container, shipping container, hi-cube container, box, sea container, container van) is a standardized reusable steel box. Intermodal containers are used to store and move materials and products efficiently and securely in the global containerized intermodal freight transport system. "Intermodal" indicates that the container can be used across various modes of transport, (from ship to rail to truck) without unloading and reloading its contents. Lengths of containers, which each have a unique ISO 6346 reporting mark, vary from 8 to 56 feet (2.438 to 17.069 m) and heights from 8 feet (2.438 m) to 9 feet 6 inches (2.896 m). There are about 17 million intermodal containers in the world of varying types to suit different cargoes.[1]

For air freight, the alternative and lighter IATA-defined unit load device is used. Non-container methods of transport include bulk cargo, break bulk cargo, and tank cars, tank trucks, and oil tankers used for liquids or gases.


Main article: Containerization

Early versions of standardized containers were used in Europe before World War II. Construction of these containers had a steel frame with wooden walls, floor, roof and doors. The first standard for containers was established by the Bureau International des Containers et du Transport Intermodal (B.I.C.) in 1933, and a second standard in 1935. These early containers were not stackable and were used primarily for transport between European countries. American containers at this time were not stackable nor standardized. In November 1932, the first container terminal in the world was opened by the Pennsylvania Rail Road Company in Enola, PA. The development of containerization was created in Europe and the US as a way to revitalize rail companies after the Wall Street Crash of 1929, in New York, and resulting economic collapse and drop in all modes of transport.[2]

Between 14–23 April 1951 in Zurich Tiefenbrunnen under the auspices of the Club Museum of Transport, Switzerland, Swiss Transportation and Bureau International des Containers et du Transport Intermodal (B.I.C.) held demonstrations of container systems with the intent to select the best solution for Western Europe. Representatives from Belgium, France, Germany, Great Britain, Italy, The Netherlands, Sweden, Switzerland, and the United States of America were present. Based on a system for waste transportation and consumer goods from the Netherlands, under the name Laadkisten, used since 1934 with permissible gross mass of the container was 3000kg with dimensions of 2.5 × 2 × 2m, reloading held by dragging rope winch tow car, was chosen as a container system for Western Europe known as European standard UIC 590, also known as "Pa-Behälter." This system has been implemented in Denmark, Belgium, the Netherlands, Luxembourg, West Germany, Switzerland and Sweden. With the gradual popularization of the large container type ISO system, "Pa-Behälter" was withdrawn from use by the railways. In the 1970s it began to be widely used for the transport of waste.[3]

The modern standardized steel shipping container has its origins in the 1950s, when commercial shipping operators and the US military started developing units such as the 6- by 6- by 6-foot steel-clad Conex box.[4] The Fruehauf Trailer Corporation created a version of a container from a semi-trailer for use in the Korean War.

A Fruehauf customer, shipping owner Malcom McLean approached Roy Fruehauf with concerns of pilfering of his shipments. Fruehauf and his Vice President of engineering, Keith Tantlinger began work on a concept that would become the modern intermodal container. A metal shipping container, which replaced the traditional break bulk method of handling dry goods and revolutionized the transport of goods and cargo worldwide. Fruehauf's V.P. of Engineering, Keith Tatlinger arranged for a team of engineers in research and development to create some designs. The majority of Fruehauf's over one thousand patents had been developed solving problems for customers. Engineers from Fruehauf collaborated with McLean to develop a design. It was perfected and patented by Fruehauf. Jim Schmidt, a Fruehauf engineer recounted stories of early container designs being raised fifty feet into the air by a crane and dropped to test strength and durability. Roy Fruehauf and Keith Tantlinger insisted that the patent be returned to industry in order to ensure standardization. Fruehauf financed McLean's Sea-Land Service, Inc., that received the container boxes manufactured by Fruehauf. The logistics method employing these containers was named Container Express (ConEx). On October 4, 1957, the first container ship, McLean's pan-Atlantic Gateway City, steamed from Port Newark, New Jersey, south to Miami.[5] In 1968, McLean began container service to South Vietnam for the US military with great success.

ISO standards for containers were published between 1968 and 1970 by the International Maritime Organization. These standards allow for more consistent loading, transporting, and unloading of goods in ports throughout the world, thus saving time and resources.[6]

The International Convention for Safe Containers is a 1972 regulation by the Inter-governmental Maritime Consultative Organization on the safe handling and transport of containers. It decrees that every container travelling internationally be supplied with a "CSC-Plate".[7][8]

In 1980 the International Longshoremen's Union argued unsuccessfully that it was their right to unload containers at the dock.[9] Longshoremen around the world struggled with this revolution in shipping goods.


A typical container has doors fitted at one end and is made of corrugated weathering steel (commonly known as "COR-TEN", a trademark of U.S. Steel Corporation) with a plywood floor.[10] Containers are 8-foot (2.44 m) wide by 8 ft 6 in (2.59 m) high, and either a nominal 20-foot (6.1 m) or 40-foot (12.19 m) long. They can be stacked up to seven units high. At each of the eight corners are castings with openings for twistlock fasteners. Although the two ends are quite rigid, containers flex during transport.[11]

Taller "hi-cube" or "high-cube" units measuring 9 feet 6 inches (2.90 m) high are common in most areas.[12] The United States and Canada often use longer units at 45 ft (13.72 m).

Container capacity is often expressed in twenty-foot equivalent units (TEU, or sometimes teu). A twenty-foot equivalent unit is a measure of containerized cargo capacity equal to one standard 20 ft × 8 ft (6.10 m × 2.44 m) (length × width) container. As this is an approximate measure, the height of the box is not considered; for example, the 9 ft 6 in (2.9 m) high-cube and the 4-foot-3-inch (1.3 m) half-height 20-foot (6.1 m) containers are also called one TEU. Similarly, the 45 ft (13.72 m) containers are also commonly designated as two TEU, although they are 45 feet (13.72 m) and not 40 feet (12.19 m) long. Two TEU are equivalent to one forty-foot equivalent unit (FEU).[13][14]


A spine car with a 20 ft tank container and an open-top 20 ft container with canvas cover
A flat-rack container loaded with a small vessel loaded by a reach stacker.

Variations on the standard container exist for use with different cargoes. These include refrigerated container units for perishable goods, tanks in a frame for bulk liquids, open-top units for top loading, and collapsible versions. Containerized coal carriers and "bin-liners" (containers designed for the efficient road and rail transportation of rubbish from cities to recycling and dump sites) are used in Europe.

Container types include:[15][16]

  • Collapsible ISO containers
  • Gas bottles
  • Generators
  • General-purpose dry vans, for boxes, cartons, cases, sacks, bales, pallets, and drums, in standard, high or half height
  • High-cube palletwide containers, for EUR-pallet compatibility
  • Insulated shipping containers
  • Refrigerated containers, for perishable goods
  • Open-top bulktainers, for bulk minerals, heavy machinery
  • Open-side containers, for loading oversize pallet
  • Platform or bolster containers, for barrels and drums, crates, cable drums, out-of-gauge cargo, machinery, and processed timber
  • Rolling-floor containers, for difficult-to-handle cargo
  • Swapbody containers
  • Tank containers, for bulk liquids and dangerous goods
  • Ventilated containers, for organic products requiring ventilation
  • Garmentainers, for shipping garments on hangers (GOH)[17][18]
  • Flushfolding flat-rack containers, for heavy and bulky semi-finished goods and out-of-gauge cargo; empty flat-racks can be stacked or shipped sideways in an ISO container
  • A multitude of specialized equipment has been installed in containers to simplify logistics - see containerized equipment for more details.


A few relevant ISO series standards include:

  • ISO 6346:1995 Freight containers—Coding, identification and marking
  • ISO 668:2013 Series 1 freight containers—Classification, dimensions and ratings
  • ISO 1161:1984 Series 1 freight containers—Corner fittings—Specification
  • ISO 1496-1:2013 Series 1 freight containers—Specification and testing—Part 1: General cargo containers for general purposes

Weights and dimensions of some common types of containers are given below. Values vary slightly from manufacturer to manufacturer.

20′ container 40′ container 40′ high-cube container 45′ high-cube container
imperial metric imperial metric imperial metric imperial metric
length 20′ 0″ 6.058 m 40′ 0″ 12.192 m 40′ 0″ 12.192 m 45′ 0″ 13.716 m
width 8′ 0″ 2.438 m 8′ 0″ 2.438 m 8′ 0″ 2.438 m 8′ 0″ 2.438 m
height 8′ 6″ 2.591 m 8′ 6″ 2.591 m 9′ 6″ 2.896 m 9′ 6″ 2.896 m
length 18′ 8 1316 5.710 m 39′ 5 4564 12.032 m 39′ 4″ 12.000 m 44′ 4″ 13.556 m
width 7′ 8 1932 2.352 m 7′ 8 1932 2.352 m 7′ 7″ 2.311 m 7′ 8 1932 2.352 m
height 7′ 9 5764 2.385 m 7′ 9 5764 2.385 m 8′ 9″ 2.650 m 8′ 9 1516 2.698 m
door aperture width 7′ 8 ⅛″ 2.343 m 7′ 8 ⅛″ 2.343 m 7′ 6" 2.280 m 7′ 8 ⅛″ 2.343 m
height 7′ 5 ¾″ 2.280 m 7′ 5 ¾″ 2.280 m 8′ 5″ 2.560 m 8′ 5 4964 2.585 m
internal volume 1,169 ft³ 33.1 m³ 2,385 ft³ 67.5 m³ 2,660 ft³ 75.3 m³ 3,040 ft³ 86.1 m³
gross weight
66,139 lb 30,400 kg 66,139 lb 30,400 kg 68,008 lb 30,848 kg 66,139 lb 30,400 kg
empty weight 4,850 lb 2,200 kg 8,380 lb 3,800 kg 8,598 lb 3,900 kg 10,580 lb 4,800 kg
net load 61,289 lb 28,200 kg 57,759 lb 26,600 kg 58,598 lb 26,580 kg 55,559 lb 25,600 kg


Intermodal containers can be the target of break-ins and burglary when left unattended since they often contain valuables. In these cases, a security system consisting of a motion detector and panel can trigger a siren, strobe, or light to deter intruders. Many panels have wireless communication so that security guards can be alerted if an alarm is triggered.

Motion detectors can be used as a security method (although items that were packed incorrectly may come loose and cause a false response from motion detectors). However, many break-ins occur by criminals cutting through a wall of the container, so the obstructed sensor becomes useless. Tomographic motion detectors work well in intermodal containers because they do not require a line of sight to detect motion. The entire container is covered by a volumetric sensing mesh that is not blocked by equipment or inventory. Tomographic motion detection is not prone to misdetection due to dirt buildup as is the case for beams and infrared sensors.

Stacking containers[edit]

Load bearing of container stacking is at the 40 ft coupling

At stacking load-bearing locations, 40-foot containers are the standard unit length, and 45 ft, 48 ft, and 53 ft all stack at the 40 ft coupling width. Other units can be stacked on top of 20 ft units only if there are two in a row (40 ft coupling width) and 20 ft units cannot be stacked on top of 40 ft units, or any other larger container.

The coupling holes are all female and it takes a double male twist lock to securely mate container stacks together.

Non-standard Sizes[edit]

The "pallet wide" containers have about a 2 inches (5.1 cm) wider floor than standard containers to accommodate Euro-pallets, common in Europe.[19] These containers feature an internal width of 2,440 mm (96.1 in) for easy loading of two 1,200 mm (47.2 in) long pallets side by side – many sea shipping providers in Europe allow these as overhangs on standard containers are sufficient and they fit in the usual interlock spaces (or with the same floor panel the side ribs of pallet-wide containers are embossed to the outside instead of being molded to the inside).[20]

Especially the 45 ft (13.72 m) pallet-wide high-cube shortsea container has gained wider acceptance, as these containers can replace the 13.6 m (44.6 ft) swap bodies that are common for truck transport in Europe. The EU has started a standardization for pallet wide containerization in the European Intermodal Loading Unit (EILU) initiative.[21]

Australian RACE containers are also slightly wider to accommodate Australia Standard Pallets.

48-foot container[edit]

The 48-foot (14.63 m) shipping container is a High Cube container in that it is 9 ft 6 in (2.90 m) tall on the exterior. It is 8 ft 6 in (2.59 m) wide which makes it 6 in (15 cm) wider than standard containers.[22] This size is used domestically in North America and may be transported on deck by ship. This size being 8-foot (2.44 m) longer and 6 in (15 cm) wider has 29% more cubic capacity than the standard 40' High Cube, yet the cost to move it by truck or rail are the same.

53-foot container[edit]

Swift 53 ft Intermodal container

Introduced in 1989,[23] the 53-foot (16.15 m) shipping container is considered a High Cube container in that it is 9 ft 6 in (2.90 m) tall on the exterior. It is 1 ft (30 cm) taller than standard height containers. It is 8 ft 6 in (2.59 m) wide which makes it 6 in (15 cm) wider than standard containers. The bigger boxes have 60% more capacity than standard 40-foot (12.19 m) containers enabling shippers to consolidate more cargo into fewer containers.[23][24][25] The original domestic 53-foot box OTR containers were introduced in 1989, but in November 2007 the first 53-foot ocean containers were introduced. All new, reinforced 53-foot boxes are built specifically for international trade and designed to withstand ocean voyages. According to APL, 53-foot containers could become the transport method of choice for customers moving cargo.[23] In March 2013 APL stated that it "no longer offers vessel space for 53-foot ocean containers in its trans-Pacific services. It has struggled to find sufficient amount of U.S. export cargo for them, while revenue on the eastbound leg has not been sufficient to cover the costs of repositioning empties back to Asia."[26]

Swap body[edit]

Swap body units do not have upper corner fixtures, but use the same bottom corner fixtures as Intermodal containers, and often have folding legs under their frame so that they can be moved between trucks without using a crane. They are generally lighter in weight.[27][28]

Reporting mark[edit]

Labelling on a container

Each container is allocated a standardized ISO 6346 reporting mark (ownership code), four characters long ending in either U, J or Z, followed by six numbers and a check digit.[29] The ownership code for intermodal containers is issued by the Bureau International des Containers et du Transport Intermodal (41 rue Réaumur, 75003 - Paris France), hence the name BIC-Code for the intermodal container reporting mark. So far there exist only four-letter BIC-Codes ending in "U".

The placement and registration of BIC Codes is standardized by the commissions TC104 and TC122 in the JTC1 of the ISO which are dominated by shipping companies. Shipping containers are labelled with a series of identification codes that includes the manufacturer code, the ownership code, usage classification code, UN placard for hazardous goods and reference codes for additional transport control and security.

Following the extended usage of pallet-wide containers in Europe the EU had started the Intermodal Loading Unit (ILU) initiative. This showed advantages for intermodal transport of containers and swap bodies. This led to the introduction of ILU-Codes defined by the standard EN 13044 which has the same format as the earlier BIC-Codes. The International Container Office BIC agreed to only issue ownership codes ending with U, J or Z. The new allocation office of the UIRR (International Union of Combined Road-Rail Transport Companies) agreed to only issue ownership reporting marks for swap bodies ending with A, B, C, D or K – companies having a BIC-Code ending with U can allocate an ILU-Code ending with K having the same preceding digits. Since July 2011 the new ILU codes can be registered, beginning with July 2014 all intermodal ISO containers and intermodal swap bodies must have an ownership code and by July 2019 all of them must bear a standard-conforming placard.[30]


A cargo container being transferred from a rail car to a flat-bed truck, lifted by a reach stacker

Containers are transferred between rail, truck and ship by container cranes at container terminals. Forklifts, reach stackers, straddle carriers, and cranes may be used to load and unload trucks or trains outside of container terminals. Swap bodys, sidelifters, tilt deck trucks and hook trucks allow transfer to and from trucks with no extra equipment.


Containers can be transported by container ship, truck and freight trains as part of a single journey without unpacking. Units can be secured in transit using "twistlock" points located at each corner of the container. Every container has a unique BIC code painted on the outside for identification and tracking, and is capable of carrying up to 20-25 metric tons. Costs for transport are calculated in twenty-foot equivalent units (TEU).


When carried by rail, containers may be carried on flatcars or well cars. The latter are specially designed for container transport, and can accommodate double-stacked containers. However the loading gauge of a rail system may restrict the modes and types of container shipment. The smaller loading gauges often found in European railroads will only accommodate single-stacked containers. In some countries, such as the United Kingdom, there are sections of the rail network through which high-cube containers cannot pass, or can pass through only on well cars. On the other hand, Indian Railways runs double-stacked containers on flatcars under 25 kV overhead electrical wires. In order to do this, the wire must be at least 7.45 metres (24 ft 5 in) above the track, but IR is able to do so because of its large loading gauge and the extra stability provided by its 1,676 mm (5 ft 6 in) track. China Railways also runs double-stacked containers under overhead wires, but must use well cars to do so, since the wires are only 6.6 metres (21 ft 8 in) above the track and 1,435 mm (4 ft 8 12 in) (standard gauge) does not provide adequate stability to run double-stacked containers on flat cars.[31]


Each year an estimated 10,000 shipping containers fall into the sea; of these 10% are expected to contain chemicals toxic to marine life.[32]


Containers can also be transported in planes, as seen within intermodal freight transport. However transporting containers in this way is typically avoided due to the cost of doing such and the lack of availability of planes which can accommodate such awkward sized cargo.

Securing loads in intermodal containers[edit]

Main article: Load securing

There are many established methods and materials available to stabilize and secure cargo in intermodal containers. Conventional restraint methods and materials such as steel strapping and wood blocking & bracing have been around for decades and are still widely used. Polyester strapping and lashing, synthetic webbings are also common today. Dunnage bags, also known as "air bags" are used to help keep unit loads in place.

Flexi-bags can also be directly loaded, stacked in food-grade containers. Indeed, their standard shape fills the entire ground surface of a 20'ISO container.

Non-shipping uses[edit]

Containerized equipment[edit]

Container-sized units are also often used for moving large pieces of equipment to temporary sites. Specialised containers are particularly attractive to militaries already using containerisation to move much of their freight around. Shipment of specialized equipment in this way simplifies logistics and may prevent identification of high value equipment by enemies. Such systems may include command and control facilities, mobile operating theatres[33] or even missile launchers[34] (such as the Russian 3M-54 Klub surface-to-surface missile).

Complete water treatment systems can be installed in containers and shipped around the world.[35]

Electric generators can be permanently installed in containers to be used for portable power.


A popup-party housed in a solar powered repurposed container

Containers have been used for other purposes at the end of their voyaging lives. Permanent or semi-permanent placement for storage is common. A container has 8,000 lb (3,629 kg) of steel, which takes 8,000 kWh (28,800 MJ) of energy to melt down. Repurposing used shipping containers is increasingly a practical solution to both social and ecological problems.

Shipping container architecture employs used shipping containers as the main framing of modular home designs, where the steel may be an integrated part of the design, or be camouflaged into a traditional looking home. They have also been used to make temporary shops, cafes, and computer datacenters, e.g., the Sun Modular Datacenter.

Intermodal containers are not strong enough for conversion to underground bunkers, as the walls cannot sustain much lateral pressure, and will collapse. Also, the wooden floor of many used containers could contain some fumigation residues, rendering them unsuitable as confined spaces, such as for prison cells or bunkers. Cleaning or replacing the wood floor can make these used containers habitable, with proper attention to such essential issues as ventilation and insulation.


See also[edit]


  1. ^ "Containers". World Shipping Council. Retrieved 2010-04-20. 'containers' of various standard sizes – 20-foot (6.1 m), 40-foot (12.19 m), 45-foot (13.72 m), 48-foot (14.63 m), and 53-foot (16.15 m) ... Aggregate container capacity is often expressed in twenty-foot equivalent units (TEU) which is a unit of capacity equal to one standard 20 ft × 8 ft (6.10 m × 2.44 m) (length × width) container.The 17 million or more container units equate to more than 26 million TEU in the global container fleet 
  2. ^ Lewandowski, Krzysztof (2014). "Czechoslovak activity to prepare European norms for containers before the Second World War" (PDF). Acta Logistica 1 (4): 1–7. ISSN 1339-5629. 
  4. ^ Intermodal Marine Container Transportation: Impediments and Opportunities, Issue 236 // National Research Council: The container revolution (page 17-18): "This led to the development after the war of the 6- by 6- by 6-foot steel-clad Container Express (Conex) box used for military shipments on commercial vessels"
  5. ^
  6. ^ Bartsch, Butsri. "Sea freight - somehow antique yet modern!". Retrieved 20 May 2013. 
  7. ^ "International Convention for Safe Containers (CSC) – Adoption: 2 December 1972; Entry into force: 6 September 1977". Retrieved 2013-02-01. 
  8. ^ International Convention for Safe Containers (Geneva, 2 December 1972)
  9. ^
  10. ^ "Shipping Container Homes Globally". Retrieved 2009-05-24. 
  11. ^ "GTRI Develops New Technologies to Secure Cargo Containers". 2009-09-07. Retrieved 2011-05-08. 
  12. ^ "Container sizes". Retrieved 2013-02-01. 
  13. ^ "The 20 Foot Shipping Container". Retrieved 2013-02-01. 
  14. ^ "20 Foot Container Dimensions, 20' Ft Containers Sizes". Retrieved 2013-02-01. 
  15. ^ "Selecting a Container" (PDF). CMA CGM Group. 2006. Retrieved 2008-02-14. 
  16. ^ "Types and dimensions". Retrieved 2013-02-01. 
  17. ^ [1][dead link]
  18. ^ "DB Schenker Logistics offers new solution for garments on hangers | 3PL". 2010-07-07. Retrieved 2013-02-01. 
  19. ^ "Standard Shipping Containers". Container container. Retrieved 2009-05-18. 
  20. ^
  21. ^ Frederik Hallbjörner, Claes Tyrén (2004). "Possible consequences of a new European container standard (EILU)" (PDF). master thesis. 
  22. ^
  23. ^ a b c "". Retrieved 2013-02-01. 
  24. ^ "53ft High Cube Container | 53' High Cube Container | Container Technology, Inc". Retrieved 2013-02-01. 
  25. ^ "Big Boxes bring Big Questions - Eric Joiner's - The Logistics and Supply Chain Blog!". 2007-11-05. Retrieved 2013-02-01. 
  26. ^
  27. ^ [2][dead link]
  28. ^ [3][dead link]
  29. ^
  30. ^ "New markings of intermodal loading units in Europe" (PDF). International Union of Combined Road-Rail Transport Companies. 2011-05-10. 
  31. ^ Raghvendra, Rao (August 26, 2008). "Rlys reaches higher, sets world record". Retrieved 2009-11-04. 
  32. ^ "Scientists to study effects of shipping containers lost at sea". Mar 9, 2011. 
  33. ^
  34. ^
  35. ^
  36. ^ pg3
International Standards
  • ASTM D5728-00 Standard Practices for Securement of Cargo in Intermodal and Unimodal Surface Transport
  • ISO 9897:1997 Freight containers – Container equipment data exchange (CEDEX) – General communication codes
  • ISO 14829:2002 Freight containers – Straddle carriers for freight container handling – Calculation of stability
  • ISO 17363:2007 Supply chain applications of RFID – Freight containers
  • ISO/PAS 17712:2006 Freight containers – Mechanical seals
  • ISO 18185-2:2007 Freight containers – Electronic seals
  • ISO/TS 10891:2009 Freight containers – Radio frequency identification (RFID) – Licence plate tag

Further reading[edit]

External links[edit]