Intermodal freight transport involves the transportation offreight in anintermodal container orvehicle, using multiple modes oftransportation (e.g.,rail,ship,aircraft, andtruck), without any handling of the freight itself when changing modes. The method reduces cargo handling, and so improves security, reduces damage and loss, and allows freight to be transported faster. Reduced costs over road trucking is the key benefit for inter-continental use. This may be offset by reduced timings for road transport over shorter distances.
Intermodal transportation has its origin in 18th centuryEngland and predates the railways. Some of the earliest containers were those used for shipping coal on theBridgewater Canal inEngland in the 1780s. Coal containers (called "loose boxes" or "tubs") were soon deployed on the early canals and railways and were used for road/rail transfers (road at the time meaninghorse-drawn vehicles).
Wooden coal containers were first used on the railways in the 1830s on the Liverpool and Manchester Railway. In 1841,Isambard Kingdom Brunel introduced iron containers to move coal from the vale ofNeath toSwansea Docks. By the outbreak of theFirst World War theGreat Eastern Railway was using wooden containers to trans-ship passenger luggage between trains and sailings via theport of Harwich.
The early 1900s saw the first adoption of covered containers, primarily for the movement of furniture and intermodal freight between road and rail. A lack of standards limited the value of this service and this in turn drove standardisation. In the U.S. such containers, known as "lift vans", were in use from as early as 1911.
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In theUnited Kingdom, containers were first standardised by theRailway Clearing House (RCH) in the 1920s, allowing both railway-owned and privately owned vehicles to be carried on standard container flats. By modern standards these containers were small, being 1.5 or 3.0 meters (4.9 or 9.8 ft) long, normally wooden and with a curved roof and insufficient strength for stacking. From 1928 theLondon, Midland & Scottish Railway offered "door to door" intermodal road-rail services using these containers. This standard failed to become popular outside the United Kingdom.
Pallets made their first major appearance duringWorld War II, when the United States military assembled freight on pallets, allowing fast transfer betweenwarehouses, trucks, trains,ships, andaircraft. Because no freight handling was required, fewer personnel were needed and loading times were decreased.
Trucktrailers were first carried by railway before World War II, an arrangement often called "piggyback", by the smallClass I railroad, theChicago Great Western in 1936. TheCanadian Pacific Railway was a pioneer in piggyback transport, becoming the first majorNorth American railway to introduce the service in 1952. In the United Kingdom, the big four railway companies offered services using standard RCH containers that could be craned on and off the back of trucks. Moving companies such asPickfords offered private services in the same way.
In 1933 in Europe, under the auspices of theInternational Chamber of Commerce, TheBureau International des Containers et du Transport Intermodal (BIC; English: International Bureau for Containers and Intermodal Transport) was established. In June 1933, the BIC decided about obligatory parameters for container use in international traffic. Containers handled by means of lifting gear, such as cranes, overhead conveyors, etc. for traveling elevators (group I containers), constructed after July 1, 1933. Obligatory Regulations:
| Category | Length [m (ft in) | [m (ft in)] | [m (ft in)] | Total mass [tons] |
|---|---|---|---|---|
| Heavy types | ||||
| Close type 62 | 3.25 m (10 ft 8 in) | 2.15 m (7 ft5⁄8 in) | 2.20 m (7 ft2+5⁄8 in) | 5 t (4.92 long tons; 5.51 short tons) |
| Close type 42 | 2.15 m (7 ft5⁄8 in) | 2.15 m (7 ft5⁄8 in) | 2.20 m (7 ft2+5⁄8 in) | |
| Open type 61 | 3.25 m (10 ft 8 in) | 2.15 m (7 ft5⁄8 in) | 1.10 m (3 ft7+1⁄4 in) | |
| Open type 41 | 2.15 m (7 ft5⁄8 in) | 2.15 m (7 ft5⁄8 in) | 1.10 m (3 ft7+1⁄4 in) | |
| Light Type | ||||
| Close type 22 | 2.15 m (7 ft5⁄8 in) | 1.05 m (3 ft5+3⁄8 in) | 2.20 m (7 ft2+5⁄8 in) | 2.5 t (2.46 long tons; 2.76 short tons) |
| Close type 201 | 2.15 m (7 ft5⁄8 in) | 1.05 m (3 ft5+3⁄8 in) | 1.10 m (3 ft7+1⁄4 in) | |
| Open type 21 | 2.15 m (7 ft5⁄8 in) | 1.05 m (3 ft5+3⁄8 in) | 1.10 m (3 ft7+1⁄4 in) | |
In April 1935, BIC established a second standard for European containers:[1]
| Category | Length [m (ftin)] | Width [m (ftin)] | High [m (ftin)] | Total mass [tons] |
|---|---|---|---|---|
| Heavy types | ||||
| Close 62 | 3.25 m (10 ft 8 in) | 2.15 m (7 ft5⁄8 in) | 2.55 m (8 ft4+3⁄8 in) | 5 t (4.92 long tons; 5.51 short tons) |
| Close 42 | 2.15 m (7 ft5⁄8 in) | 2.15 m (7 ft5⁄8 in) | 2.55 m (8 ft4+3⁄8 in) | |
| Open 61 | 3.25 m (10 ft 8 in) | 2.15 m (7 ft5⁄8 in) | 1.125 m (3 ft8+5⁄16 in) | |
| Open 41 | 2.15 m (7 ft5⁄8 in) | 2.15 m (7 ft5⁄8 in) | 1.125 m (3 ft8+5⁄16 in) | |
| Light Type | ||||
| Close 32 | 1.50 m (4 ft 11 in) | 2.15 m (7 ft5⁄8 in) | 2.55 m (8 ft4+3⁄8 in) | 2.5 t (2.46 long tons; 2.76 short tons) |
| Close 22 | 1.05 m (3 ft5+3⁄8 in) | 2.15 m (7 ft5⁄8 in) | 2.55 m (8 ft4+3⁄8 in) | |
In the 1950s, a new standardized steelIntermodal container based on specifications from theUnited States Department of Defense began to revolutionize freight transportation. TheInternational Organization for Standardization (ISO) then issued standards based upon the U.S. Department of Defense standards between 1968 and 1970.
TheWhite Pass & Yukon Route railway acquired the world's firstcontainer ship, theClifford J. Rogers, built in 1955, and introduced containers to its railway in 1956. In the United Kingdom the modernisation plan, and in turn theBeeching Report, strongly pushed containerization.British Railways launched theFreightliner service carrying 8-foot (2.4 m) high pre-ISO containers. The older wooden containers and the pre-ISO containers were rapidly replaced by 10-and-20-foot (3.0 and 6.1 m) ISO standard containers, and later by 40-foot (12 m) containers and larger.
In the U.S., starting in the 1960s, the use of containers increased steadily. Rail intermodal traffic tripled between 1980 and 2002, according to theAssociation of American Railroads (AAR), from 3.1 million trailers and containers to 9.3 million. Large investments were made in intermodal freight projects. An example was the US$740 millionPort of Oakland intermodal rail facility begun in the late 1980s.[2][3]
Since 1984, a mechanism for intermodal shipping known asdouble-stack rail transport has become increasingly common. Rising to the rate of nearly 70% of the United States' intermodal shipments, it transports more than one million containers per year. Thedouble-stack rail cars design significantly reduces damage in transit and provides greater cargo security by cradling the lower containers so their doors cannot be opened. A succession of large, new, domestic container sizes was introduced to increase shipping productivity. In Europe, the more restrictedloading gauge has limited the adoption of double-stack cars. However, in 2007 theBetuweroute, a railway fromRotterdam to theGerman industrial heartland, was completed, which may accommodate double-stacked containers in the future. Other countries, likeNew Zealand, have numerous low tunnels and bridges that limit expansion for economic reasons.
Since electrification generally predated double-stacking, the overhead wiring was too low to accommodate it. However, India is building some freight-only corridors with the overhead wiring at7.45 m above rail, which is high enough.[4]
Containers, also known as intermodal containers or ISO containers because the dimensions have been defined by ISO, are the main type of equipment used in intermodal transport, particularly when one of the modes of transportation is by ship. Containers are 8-foot (2.4 m) wide by 8-foot (2.4 m) or 9-foot-6-inch (2.90 m) high. Since introduction, there have been moves to adopt other heights, such as 10-foot-6-inch (3.20 m). The most common lengths are 20 feet (6.1 m), 40 feet (12 m), 45 feet (14 m), 48 and 53 feet (15 and 16 m), although other lengths exist. The three common sizes are:
In countries where the railwayloading gauge is sufficient,truck trailers are often carried by rail. Variations exist, including open-topped versions covered by a fabric curtain are used to transport larger loads. A container called atanktainer, with a tank inside a standard container frame, carries liquids.Refrigerated containers (reefer) are used for perishables.Swap body units have the same bottom corners as intermodal containers but are not strong enough to be stacked. They have folding legs under their frame and can be moved between trucks without using a crane.
Handling equipment can be designed with intermodality in mind, assisting with transferring containers between rail, road and sea. These can include:
According to theEuropean Commission Transportation Department "it has been estimated that up to 25% of accidents involving trucks can be attributable to inadequate cargo securing".[7]Cargo that is improperly secured can cause severe accidents and lead to the loss of cargo, the loss of lives, the loss of vehicles, ships and airplane; not to mention the environmental hazards it can cause.There are many different ways and materials available to stabilize and secure cargo in containers used in the various modes of transportation. ConventionalLoad Securing methods and materials such as steel banding and wood blocking & bracing have been around for decades and are still widely used. In the last few years the use of several, relatively new and unknownLoad Securing methods have become available through innovation and technological advancement including polyester strapping and -lashing, synthetic webbings andDunnage Bags, also known as air bags.
Container ships are used to transport containers by sea. These vessels are custom-built to hold containers. Some vessels can hold thousands of containers. Their capacity is often measured inTEU or FEU. These initials stand for "twenty-foot equivalent unit", and "forty-foot equivalent unit", respectively. For example, a vessel that can hold 1,000 40-foot containers or 2,000 20-foot containers can be said to have a capacity of 2,000 TEU. After the year 2006, thelargest container ships in regular operation are capable of carrying in excess of 15,000 TEU.[8][9]
On board ships they are typically stacked up to seven units high.
A key consideration in the size of container ships is that larger ships exceed the capacity of important sea routes such as the Panama and Suez canals. The largest size of container ship able to traverse the Panama canal is referred to asPanamax, which is presently around 5,000 TEU. A third set of locks is planned as part of thePanama Canal expansion project to accommodate container ships up to 12,000 TEU in future, comparable to the presentSuezmax.[10]
Very large container ships also require specialized deep water terminals and handling facilities. The container fleet available, route constraints, and terminal capacity play a large role in shaping global container shipment logistics.[11][12]
Increasingly, containers are shipped by rail incontainerwell cars. These cars resemble flatcars but have a container-sized depression, or well, in the middle of the car between thebogies or trucks. Some container cars are built as an articulated "unit" of three or five permanently coupled cars, each having a single bogie rather than the two bogies normally found on freight cars.
Containers can be loaded onflatcars or incontainer well cars. In North America, Australia and Saudi Arabia, wherevertical clearances are generally liberal, this depression is sufficient for two containers to be loaded in a "double-stack" arrangement. InEurope, height restrictions imposed by smallerstructure gauges, and frequent overheadelectrification, prevent double-stacking. Containers are therefore hauled one-high, either on standard flatcars or otherrailroad cars – but they must be carried in well wagons on lines built early in theIndustrial Revolution, such as in the United Kingdom, whereloading gauges are relatively small.
610 mm (2 ft) narrow-gauge railways have smaller wagons that do not readily carry ISO containers, nor do the 30-foot (9.14 m) long and 7-foot (2.13 m) wide wagons of the762 mm (2 ft 6 in) gaugeKalka-Shimla Railway. Widernarrow gauge railways of e.g.914 mm (3 ft) and1,000 mm (3 ft 3+3⁄8 in) gauge can take ISO containers, provided that theloading gauge allows it.
It is also common inNorth America andAustralia to transportsemi-trailers on railwayflatcars orspine cars, an arrangement called "piggyback" or TOFC(trailer on flatcar) to distinguish it fromcontainer on flatcar (COFC). Some flatcars are designed with collapsible trailer hitches so they can be used for trailer or container service.[13] Such designs allow trailers to be rolled on from one end, though lifting trailers on and off flatcars by specialized loaders is more common. TOFC terminals typically have large areas for storing trailers pending loading or pickup.[14]
Thievery has become a problem in North America. Sophisticated thieves learn how to interpret the codes on the outside of containers to ascertain which ones have easily disposable cargo. They break into isolated containers on long trains, or even board slowly moving trains to toss the items to accomplices on the ground.[15]
Trucking is frequently used to connect the "linehaul" ocean and rail segments of a global intermodal freight movement. This specialized trucking that runs between ocean ports, rail terminals, and inland shipping docks, is often calleddrayage, and is typically provided by dedicated drayage companies or by the railroads.[16]As an example, since many rail lines in the United States terminate in or around Chicago, Illinois, the area serves as a common relay point for containerized freight moving across the country. Many of the motor carriers call this type of drayage "crosstown loads" that originate at one rail road and terminate at another. For example, a container destined for the east coast from the west will arrive in Chicago either via the Union Pacific or BNSF Railway and have to be relayed to one of the eastern railroads, either CSX or Norfolk Southern.
Barges utilisingro-ro and container-stacking techniques transport freight on large inland waterways such as theRhine/Danube in Europe and theMississippi River in the U.S.[5]
The termlandbridge orland bridge is commonly used in the intermodal freight transport sector. When a containerized oceanfreight shipment travels across a large body of land for a significant distance, that portion of the trip is referred to as the "land bridge" and themode of transport used israil transport. There are three applications for the term.
The termreverse land bridge refers to amicro land bridge from an east coast port (as opposed to a west coast port in the previous examples) to an inland destination.
Generally modern, bigger planes usually carry cargo in the containers. Sometimes even the checked luggage is first placed into containers, and then loaded onto the plane.[19][unreliable source?] Of course because of the requirement for the lowest weight possible (and very important, little difference in the viable mass point), and low space, specially designed containers made from lightweight material are often used. Due to price and size, this is rarely seen on the roads or in ports. However, large transport aircraft make it possible to even load standard container(s), or use standard sized containers made of much lighter materials liketitanium oraluminium.
| Company | TEU capacity[20] | Number of ships[21] |
|---|---|---|
| A.P. Moller-Maersk Group | 2,996,188 | 585 |
| Mediterranean Shipping Company | 2,678,779 | 496 |
| CMA CGM | 1,819,351 | 460 |
| Evergreen Marine Corporation | 931,849 | 195 |
| Hapag-Lloyd | 930,398 | 174 |
| COSCO | 870,222 | 162 |
| CSCL | 684,640 | 134 |
| Hamburg Süd | 645,889 | 136 |
| Hanjin Shipping | 626,217 | 104 |
| OOCL | 561,522 | 104 |
| MOL | 554,425 | 98 |
| Yang Ming Marine Transport Corporation | 538,912 | 102 |
| APL | 535,007 | 86 |
| UASC | 512,785 | 57 |
| NYK Line | 495,723 | 104 |
| K Line | 386,265 | 66 |
| Hyundai Merchant Marine | 379,392 | 57 |
| Pacific International Lines | 362,131 | 147 |
| Zim | 358,264 | 82 |
| Wan Hai Lines | 215,244 | 85 |
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| Overview |  | |
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| Transport | ||
| Handling | ||
| Types | ||
| Other | ||
