Double-stack rail transport

Double-stack rail transport is a form of intermodal freight transportation where intermodal containers are stacked two high on railroad cars. Introduced in the United States in 1984, double stacking has become an industry standard throughout North America since then, with more routes being adapted for double stack containers. A succession of larger shipping container sizes (larger than ISO shipping standards) have been introduced to further increase shipping productivity on shipments within North America. Australia has also adopted a succession of larger shipping container sizes for domestic intermodal transport.
Double stack rail transport has spread to other parts of the world, and is in use in the United States, Canada, Mexico, Australia, Brazil, China, India, Kenya, Panama and Saudi Arabia. Double stacking continues to expand even further, although small loading gauges and other infrastructure limitations have proven to be a major impediment thus far.
== Well cars ==
Well cars feature a container 'well' that sits close to the tracks, which allows containers to be carried lower than on a standard flatcar, and allow for containers to be double stacked where clearance permits. The well cars' main advantages include increased stability due to lower center of gravity and lower tare weights.
Well cars can be constructed as multi-pack articulated units, typically between three and five packs, connected by articulated connectors. Three and five-pack articulated well cars are very well utilized in North America due to more generous axle loadings. Five pack articulated well cars were used in Australia in the late 1980's, however due to Australia's relatively restrictive axle loads, most articulated well cars in Australia today are bar connected with no shared bogies. Restrictive axle loadings in other parts of the world mean that well cars are largely single platform.
Econo Stack well cars are another (bigger and bulkier) variation of conventional units and their purpose is to allow greater support for double stack containers. Main downside is that they don't allow for containers larger than 45' to be carried. Are only used in North America.
Due to the broad gauge (1,676 mm) systems in India and Pakistan, containers can be double stacked on regular flat cars. While standard gauge (1,435 mm) systems in North America and Australia require the use of well cars to double stack containers, the United Kingdom also require use of well cars to transport 9'6" (2.9 m) or larger containers due to very restrictive loading gauges on many parts of their system. Brazil also uses well cars to double stack containers on Irish broad gauge (1,600 mm).
== Outside North America ==
Double stacking has spread to many other parts of the world, however restrictive clearances and electrification systems have been been a major impediment, most notably in Europe. Double stacking also has yet to occur on gauges smaller than standard gauge (1,435 mm).
* Australia - One of the few regions outside North America where double stacking occurs on a widespread scale, and perhaps the first outside North America to adopt double stacking. Double stacked trains operate on the East-West transcontinental railway from Parkes (NSW) and Adelaide to Perth, and the Adelaide-Darwin railway. The Inland Railway between Melbourne and Brisbane will be built for the operation of double stacked trains, as will the future Tennant Creek (NT)-Mount Isa (Queensland) railway.
* Brazil - Brado Logistica commenced the operation of double stack trains in June 2019.
* China - Double stacked trains operate on routes with raised 25kV AC electrification systems. Double stack trains were first introduced between Shanghai and Beijing in 2004, with over 10,000 kilometers of double stack routes planned. However double stacking two 9'6" (2.9 m) containers is impossible due to overhead wiring not being high enough.
* India - Mundra Port and Pipavav Port operate double stacked trains on certain freight only lines with no electrification. However the Dedicated Freight Corridors will allow for double stacked trains under 25kV AC electrification systems. One of only four regions where two 9'6" (2.9 m) containers can be double stacked (only other three being North America, Australia and the Arabian Peninsula). Triple stacking of 6'6" (1.98 m) containers was mooted without success in 2006, however, 6'4" "dwarf" containers are double stacked.
* Kenya - Double stacked trains run on the Mombasa-Nairobi-Naivasha standard gauge railway (SGR), the first such train launched on October 1, 2018. The SGR Stage 2 to the Uganda border will also be built for the operation of double stacked trains. 25kV AC electrification is intended to be added to the project in the future (similar to the Chinese system).
* Netherlands - The Betuweroute, a dedicated rail freight link between the Port of Rotterdam and the German border has had all bridges and tunnels on the route engineered for double stacked trains. However, due to the 25kV AC electrification systems being too low for double stacked containers, and double stacking being impossible on the German rail system, no double stack trains have actually used the line as of yet.
* Panama - Double stacked trains operate on the rebuilt Panama Canal Railway.
* Saudi Arabia - Double stacked trains operate on the Saudi Railways Organisation freight only line between Dammam and Riyadh. The proposed 'Saudi Landbridge' to Jeddah, and Gulf Coast Council (GCC) railway along Saudi's east coast will be built for double stack trains.
* Uganda - The upcoming standard gauge railway system will feature a loading gauge big enough for double stacked trains under 25kV AC electrification systems (similar to the Chinese system). Dependent on Kenya's SGR reaching the Kenya border.
* United Arab Emirates - The Etihad Rail network is designed with a loading gauge big enough to accommodate double stacked trains. Stage 1 from Al Ruwais to Liwa has been completed and is operational, with Stage 2 to the Saudi/Emirates border, Abu Dhabi and Dubai now underway. However, no such trains have used the system as of yet.
* United Kingdom - Due to the restrictive loading and structure gauges on British railways, double stacking is impossible, even on the Channel Tunnel Rail Link. However, well cars are used on many parts of the UK system to transport 9'6" (2.9 m) shipping containers, where the loading gauge is W9 or smaller.
Category:Rolling Stock