An intermodal container (also known as a container, freight container, ISO container, shipping container, hi-cube container, box, sea container) 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.
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.
- 1 History
- 2 Description
- 3 Types
- 4 Specifications
- 5 Security
- 6 Stacking containers
- 7 Non-standard Sizes
- 8 Reporting mark
- 9 Handling
- 10 Transport
- 11 Securing loads in intermodal containers
- 12 Non-shipping uses
- 13 See also
- 14 References
- 15 Further reading
- 16 External links
The 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.
Shipping owner Malcom McLean worked with engineer Keith Tantlinger to develop the modern intermodal container. 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. 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.
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".
In 1980 the International Longshoremen's Union argued unsuccessfully that it was their right to unload containers at the dock. 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. 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.
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).
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.
- Collapsible ISO containers
- Gas bottles
- 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)
- 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 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|
|length||19′ 10 1⁄2″||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 13⁄16″||5.710 m||39′ 5 45⁄64″||12.032 m||39′ 4″||12.000 m||44′ 4″||13.556 m|
|width||7′ 8 19⁄32″||2.352 m||7′ 8 19⁄32″||2.352 m||7′ 7″||2.311 m||7′ 8 19⁄32″||2.352 m|
|height||7′ 9 57⁄64″||2.385 m||7′ 9 57⁄64″||2.385 m||8′ 9″||2.650 m||8′ 9 15⁄16″||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 49⁄64″||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|
|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.
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.
The "pallet wide" containers have about a 2 inches (5.1 cm) wider floor than standard containers to accommodate Euro-pallets, common in Europe. 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).
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.
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. 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.
Introduced in 1989, 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. 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. 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."
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.
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. 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.
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 1⁄2 in) (standard gauge) does not provide adequate stability to run double-stacked containers on flat cars.
Each year an estimated 10,000 shipping containers fall into the sea; of these 10% are expected to contain chemicals toxic to marine life.
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
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.
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.
The Russian 3M-54 Klub surface-to-surface missile can be launched from a platform based on shipping containers, and transported as one.
Complete water treatment systems are installed in containers by the manufacturer and shipped around the world 
Electrical generators permanently installed in containers are used for portable power.
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'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
- 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"
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- International Convention for Safe Containers (Geneva, 2 December 1972)
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- 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
- George, Rose. Ninety Percent of Everything: Inside Shipping, the Invisible Industry That Puts Clothes on Your Back, Gas in Your Car, and Food on Your Plate (2013), describes typical sea voyage excerpt and text search
- International Organization for Standardization (ISO), Freight containers, Volume 34 of ISO standards handbook, International Organization for Standardization, 4th edition, 2006. ISBN 92-67-10426-8
- Levinson, Marc. The Box: How the Shipping Container Made the World Smaller and the World Economy Bigger, Princeton, N.J. : Princeton University Press, 2006. ISBN 0-691-12324-1 excerpt and text search
- Donovan, Arthur & Bonney, Joseph "The Box That Changed The World", East Windsor, New Jersey, Commonwealth Business Media, 2006 ISBN 978-1-891131-95-0
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