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[[Image:Airline hub-1995.svg|thumb|Hub and spoke airline route structures. Los Angeles and Denver are used as hubs.]]
The '''hub-and-spoke distribution paradigm''' (or '''model''' or '''network''') is a system of connections arranged like a [[chariot]] wheel, in which all traffic moves along ''[[spoke]]s'' connected to the ''[[Transport hub|hub]]'' at the center. The model is commonly used in industry, in particular in [[transport]], [[telecommunications]] and [[freight]], as well as in [[distributed computing]].
 
==Analysis of the model==
{{section OR|date=December 2011}}
The hub-and-spoke model is most frequently compared to the [[point-to-point transit]] model.
 
===Benefits===
* For a network of ''n''' nodes, only ''n'' - 1 routes are necessary to connect all nodes; that is, the upper bound is ''n'' - 1, and the [[big O notation|complexity]] is O(''n''). This compares favorably to the <math>\frac{n(n-1)}{2}</math> routes, or O(''n''<sup>2</sup>), that would be required to connect each node to every other node in a point-to-point network.  For example, in a system with 10 destinations, the spoke-hub system requires only 9 routes to connect all destinations, while a true point-to-point system would require 45 routes.
 
* The small number of routes generally leads to more efficient use of transportation resources. For example, aircraft are more likely to fly at full capacity, and can often fly routes more than once a day.
 
*Complicated operations, such as package sorting and accounting, can be carried out at the hub, rather than at every node.
 
*Spokes are simple, and new ones can be created easily.
 
===Drawbacks===
*Because the model is centralized, day-to-day operations may be relatively inflexible. Changes at the hub, or even in a single route, could have unexpected consequences throughout the network. It may be difficult or impossible to handle occasional periods of high demand between two spokes.
*Route scheduling is complicated for the network operator. Scarce resources must be used carefully to avoid starving the hub. Careful traffic analysis and precise timing are required to keep the hub operating efficiently.
*The hub constitutes a bottleneck or [[single point of failure]] in the network. Total cargo capacity of the network is limited by the hub's capacity. Delays at the hub (caused, for example, by bad weather conditions) can result in delays throughout the network. Delays at a spoke (from mechanical problems with an airplane, for example) can also affect the network.
*Cargo must pass through the hub before reaching its destination, requiring longer journeys than direct point-to-point trips. This trade-off may be desirable for freight, which can benefit from sorting and consolidating operations at the hub, but not for time-critical cargo and passengers.
* Two trips are required to reach most of the destinations. Arriving at the hub and spending some time there increases the duration of the journey. Missing the connecting bus, flight, or train is possible and may be more troublesome than just a delay.
 
==Commercial aviation==
{{Main|Airline hub}}
In 1955 [[Delta Air Lines]] pioneered the hub and spoke system at its hub in [[Atlanta, Georgia|Atlanta]], [[Georgia (U.S. state)|Georgia]],<ref>[http://www.delta.com/about_delta/corporate_information/delta_stats_facts/delta_through_decades/index.jsp Delta Air Lines Newsroom - Press Kit]. Delta.com. Retrieved on 2013-08-16.</ref> in an effort to compete with [[Eastern Air Lines]]. In the mid-1970s [[FedEx Corporation|FedEx]] adopted the hub and spoke model for overnight package delivery, and after the airline industry was [[Airline Deregulation Act|deregulated]] in 1978, Delta's hub and spoke paradigm was adopted by several other airlines.
 
Airlines have extended the hub-and-spoke model in various ways. One method is to create additional hubs on a regional basis, and to create major routes between the hubs. This reduces the need to travel long distances between nodes that are close together. Another method is to use [[Focus city|focus cities]] to implement point-to-point service for high traffic routes, bypassing the hub entirely.
 
==Transportation==
The spoke-hub model is applicable to other forms of transportation:
*[[Ship transport|Sea transport]], where [[feeder ship]]s transport shipping containers from different ports to a central container terminal to be loaded onto larger vessels.
*[[Cargo airline]]s; for example, most [[UPS Airlines]] flights travel through its "[[Worldport (UPS air hub)|Worldport]]" at [[Louisville International Airport]], and a significant portion of [[FedEx Express]] parcels are processed at its "SuperHub" at [[Memphis International Airport]].
*[[Freight rail transport]], where cargo is hauled to a central exchange terminal. At the terminal, shipping containers are loaded from one freight car to another, and [[classification yard]]s (marshalling yards) are used to sort freight cars into trains and divide them according to varying destinations.
*[[Public transport|Public transit]] utilizes various [[transport hub]]s to allow passengers to transfer between different lines or transportation modes.
 
For passenger [[road transport]], the spoke-hub model does not apply because drivers generally take the shortest or fastest route between two points.
 
==Industrial distribution==
The hub-and-spoke model has also been used in economic geography theory to classify a particular type of industrial district. [[Ann Markusen]], an economic geographer, theorised about industrial districts, where a number of key industrial firms and facilities act as a hub, with associated businesses and suppliers benefiting from their presence and arranged around them like the spokes of a wheel. The chief characteristic of such hub-and-spoke industrial districts is the importance of one or more large companies, usually in one industrial sector, surrounded by smaller, associated businesses. Examples of cities with such districts include [[Seattle]] (where [[Boeing]] was founded), [[Silicon Valley]] (a high tech hub), and [[Toyota City]], with [[Toyota Motor Corporation|Toyota]].
 
==East Asian relations==
In the sphere of East Asian relations, according to [[Victor Cha]], hub-and-spokes refers to the network of bilateral alliances between United States and other individual East Asian countries. This system constructs a dominant bilateral security architecture in East Asia, differing from the multilateral security architecture in Europe. United States acts as a "hub" and Asian countries such as [[South Korea|Republic of Korea(ROK),]] [[Republic of China|Republic of China(ROC)]] and [[Japan]] fall under the category "spokes." Whereas there is a strong alliance between the hub and the spoke, there are no firmly established connections between the spokes themselves. <ref>{{cite doi|10.1162/isec.2010.34.3.158}}</ref>
 
This system was famously inspired by [[John Foster Dulles]], who served as US Secretary of State under the [[Eisenhower]] administration from 1953 to 1959. He addressed this term twice in Tokyo and once at [[San Francisco Peace Treaty|the San Francisco Peace Treaty]] of September 1951. This led to talks for bilateral peace treaty between US and Japan. [[Security Treaty Between the United States and Japan|The US-Japan Security Treaty]] of 1951, [[U.S.-South Korea Status of Forces Agreement|US-Republic of Korea Defense Treaty]] of 1953 or [[Taiwanese identity|US-Republic of China Security Treaty]] of 1954 are some of the examples that manifests these bilateral relations. <ref>{{cite doi|10.1162/002081802760199890}}</ref>
 
==See also==
*[[Hubs and Nodes]]
*[[Roundabout]] (traffic circle)
*[[Foreign policy of the United States]] for an example of international coordination through a third country.
* [[FedEx]]
* [[United Parcel Service]]
* [[Point-to-point transit]] (alternate shipping model)
 
==References==
{{Reflist}}
* Badcock, B. A., 2002, ''Making Sense of Cities: A Geographical Survey'', London: Arnold, pp.&nbsp;63–94.
* Lawrence, H., 2004, "Aviation and the Role of Government", London: Kendall Hunt, pp.&nbsp;227–230.
* Markusen, A., 1996, "Sticky Places in Slippery Space: A Typology of Industrial Districts", in ''Economic Geography'', '''72''': 293–313.
 
{{DEFAULTSORT:Spoke-Hub Distribution Paradigm}}
[[Category:Commercial item transport and distribution]]

Latest revision as of 03:45, 29 December 2014

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