Intermodal freight transport
Intermodal freight transport involves the transportation of freight in an intermodal container or vehicle, using multiple modes oftransportation (rail, ship, and truck), without any handling of the freight itself when changing modes. The method reduces cargo handling, and so improves security, reduces damages and losses, and allows freight to be transported faster. Reduced costs over road trucking is the key benefit for intracontinental use. This may be offset by reduced timings for road transport over shorter distances.
Intermodal transportation goes back to the 18th century and predates the railways. Some of the earliest containers were those used for shipping coal on the Bridgewater Canal in England 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 meaning horse drawn vehicles).[edit]Prehistory
Wooden coal containers used on railways go back to the 1830s on the Liverpool and Manchester Railway. In 1841 Isambard Kingdom Brunel introduced iron containers to move coal from the vale ofNeath to Swansea Docks. By the outbreak of the First World War the Great Eastern Railway was using wooden containers to trans-ship passenger luggage between trains and sailings via the port ofHarwich.
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.
[edit]History
In the United Kingdom containers were first standardised by the Railway 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 long (5 or 10 ft), normally wooden and with a curved roof and insufficient strength for stacking. From 1928 the London, Midland and 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 during World War II, when the United States military assembled freight on pallets, allowing fast transfer betweenwarehouses, trucks, trains, ships, and aircraft. Because no freight handling was required, fewer personnel were required and loading times were decreased.
Truck trailers were first carried by railway before World War II, an arrangement often called "piggyback", by the small Class I railroad, the Chicago Great Western in 1936. The Canadian Pacific Railway was a pioneer in piggyback transport, becoming the first major North American railway to introduce the service in 1952. In the United Kingdom the big four railway companies offered services using standard RCH containers which could be craned on and off the back of trucks. Moving companies such as Pickfords offered private services in the same way.
In the 1950s container use started to revolutionize freight transportation. The United States Department of Defense produced specifications for standard containers for military use of 8-foot (2.4 m) by 8-foot (2.4 m) square cross section in units of 10-foot (3.0 m) long. The International Organization for Standardization (ISO) issued standards based upon the U.S. Department of Defense standards between 1968 and 1970, ensuring interchangeability between different modes of transportation worldwide. These rectangular stackable containers became known as ISO containers.
One pioneering railway was the White Pass and Yukon Route, which acquired the world's first container ship, the Clifford J. Rogers, built in 1955, and introduced containers to its railway in 1956. In the United Kingdom the modernisation plan and in turn the Beeching Report strongly pushed containerisation. The British Railways freightliner service was launched carrying 8-foot (2.4 m) high pre-ISO containers. The older wooden containers and the pre-ISO containers were rapidly replaced by 10-foot (3.0 m) and 20-foot (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 the Association 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 USD $740,000,000 Port of Oakland intermodal rail facility begun in the late 1980s.[1][2]
[edit]Double-stacked container transport
Main article: Double-stack rail transport
Since 1984, a mechanism for intermodal shipping known as double-stack rail transport has become increasingly common. Rising to the rate of nearly 70% of United States intermodal shipments, it transports more than one million containers per year. The double-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 restricted loading gauge has limited the adoption of double-stack cars. However, in 2007 the Betuweroute was completed, a railway from Rotterdam to the German industrial heartland, which may accommodate double stacked containers in the future. Other countries, like New Zealand, have numerous low tunnels and bridges, which limits 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 at 7.45 m above rail, which is high enough.[3]
[edit]Equipment
[edit]Containers
Main article: Intermodal freight shipping container
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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) high. Since introduction, there have been moves to adopt other heights, such as 8-foot-6-inch (2.59 m), 9-foot-6-inch (2.90 m) and 10-foot-6-inch (3.20 m). The most common lengths are 20 feet (6.1 m) nominal or 19 feet (5.8 m) - 101⁄2 in (0.27 m) actual, 40 feet (12 m), 48 feet (15 m) and 53 feet (16 m), although other lengths exist. They are made of steel and can be stacked atop one another (a popular term for a two-high stack is "double stack").
Onboard ships they are typically stacked up to seven units high. They can be carried by truck, rail, container ship, or aeroplane. When carried by rail, containers can be loaded on flatcars or in container well cars. In Europe, stricter railway height restrictions (smaller loading gauge and structure gauge) and overhead electrification prevent containers from being stacked two high, and containers are hauled one high either on standard flatcars or other railroad cars. Taller containers are often carried in well cars (not stacked) on older European railway routes where the loading gauge is particularly small.
Some variations on the standard container exist. 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 are used for perishables. There is also the swap body, which is typically used for road and rail transport. Built too lightly to be stacked, they have folding legs under their frame so that they can be moved between trucks without using a crane.
Various non-standard container forms are commonly used. These include non-stackable open box containers, and several slightly non-standard geometries. European containers are often about two inches wider than the ISO standard although otherwise conformant, which can carry the euro-pallet standard pallet load. Specialised containers used in Europe include containerised coal carriers, and recently "bin-liners" - containers designed for the efficient road/rail transportation of rubbish from cities to recycling and dump sites.
In countries where the loading gauge is sufficient, truck trailers are often used for freight that is transported primarily by road and rail. Typically, regular semi-trailers can be used, and do not need to be specially designed.
[edit]Handling equipment
Handling equipment can be designed with intermodality in mind, assisting with transferring containers between rail, road and sea. These can include:
- Transtainers for transferring containers from sea-going vessels onto either trucks or rail wagons. A transtainer is mounted on rails with a large boom spanning the distance between the ship's cargo hold and the quay, moving parallel to the ship's side.[4]
- Gantry cranes, also known as straddle carriers, are able to straddle rail and road vehicles, allowing for quick transfer of containers. A spreader beam moves in several directions allowing accurate positioning of the cargo.[4]
- Grappler lift, which is very similar to a straddle carrier.
- Reach stackers are fitted with lifting arms as well as spreader beams and lift containers to swap bodies or stack containers on top of each other.[4]
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[edit]Load Securing in Intermodal Containers
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According to the European Commission Transportation Department “it has been estimated that up to 25% of accidents involving trucks can be attributable to inadequate cargo securing”.[5] 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. Conventional Load 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 unknown Load Securing methods have become available through innovation and technological advancement including polyester strapping and -lashing, synthetic webbings and Dunnage Bags, also known as air bags.
[edit]Intermodal Vehicles
[edit]Rail transport
In North America, containers are often shipped by rail in container well cars. These cars resemble flatcars but the newer ones have a container-sized depression, or well, in the middle (between the bogies or "trucks") of the car. This depression allows for sufficient clearance to allow two containers to be loaded in the car in a "double stack" arrangement. The newer container cars also are specifically built as a small articulated "unit", most commonly in components of three or five, whereby two components are connected by a single bogie as opposed to two bogies, one on each car. (The photo above under "Equipment" shows an example of the new setup.) Double stacking is also used in parts of Australia. On some older railways, particularly in the United Kingdom, the use of well cars is necessary to carry single stacked large containers within the loading gauge.
It is also common in North America to transport semi-trailers on railway flatcars or spine cars, an arrangement called "piggyback" or TOFC (trailer on flatcar)to distinguish it from container on flatcar (COFC). Some flatcars are designed with collapsable trailer hitches so they can be used for trailer or container service.[6] 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.[7]
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[edit]Container ships
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 in TEU 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. In the year 2005, the largest container ships in regular operation are registered to carry in excess of 8,000 TEU.
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 as Panamax, which is presently around 5,000 TEU. A third set of locks is planned as part of the Panama Canal expansion project to accommodate container ships up to 12,000 TEU in future, comparable to the present Suezmax.
It costs about $8000[who?][when?] to ship a container from East Asia to North America[where?] when oil is at $100/barrel. As the price of oil increases, shipping costs increase.
Very large container ships also require specialized deep water terminals. The container fleet available, route constraints, and terminal capacity play a large role in shaping global container shipment logistics.[8][9]
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[edit]Trucking
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 called drayage, and is typically provided by dedicated drayage companies or by the railroads.[10]
[edit]Barges
Barges utilising ro-ro and container-stacking techniques transport freight on large inland waterways such as the Rhine/Danube in Europe and the Mississippi River in the U.S.[4]
[edit]Landbridge Application
The term landbridge or land bridge is commonly used in the intermodal freight transport sector in reference to a containerized ocean freight shipment which travels across a large body of land for a significant part of the trip, en-route to its final destination; Of which the land portion of the trip is referred to as the "landbridge" and the mode of transport used is rail transport. There are three applications for the term.
- Land bridge - An intermodal container shipped by ocean vessel from country A to country B, land bridges across an entire body of land/country/continent, en-route. For example, a container shipment from China to Germany, is loaded onto a ship in China, unloads at a Los Angeles (California) port and travels via rail transport to a New York (New York) port, and loads on a ship for Hamburg.
- Mini Land bridge - An intermodal container shipped by ocean vessel from country A to country B, passes across a large portion of land in either country A or B. For example, a container shipment from China to New York (New York), is loaded onto a ship in China, unloads at a Los Angeles (California) port and travels via rail transport to New York (New York), the final destination.
- Micro Land bridge - An intermodal container shipped by ocean vessel from country A to country B, passes across a large portion of land to reach an interior inland destination. For example, a container shipment from China to Denver (Colorado), is loaded onto a ship in China, unloads at a Los Angeles (California) port and travels via rail transport to Denver (Colorado), the final destination.[11][12]
The term reverse landbridge refers to a micro land bridge from an east coast port (as opposed to a west coast port in the previous examples) to an inland destination.
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