Spoke–hub distribution paradigm
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The spoke-hub distribution paradigm (or model or network) is a system of connections arranged like a wire wheel in which all traffic moves along spokes connected to the hub at the center. The model is commonly used in industry, particularly in transport, telecommunications, freight, and distributed computing (where it is known as a star network).
The hub-and-spoke model is most frequently compared to the point-to-point transit model.
- For a network of n nodes, only n - 1 routes are necessary to connect all nodes so the upper bound is n - 1, and the complexity is O(n). That compares favorably to the routes, or O(n2), which 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, and a true point-to-point system would require 45 routes.
- The small number of routes may lead 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 so new ones can easily be created.
- Because the model is centralized, day-to-day operations may be relatively inflexible, and changes at the hub, even in a single route, may have unexpected consequences throughout the network. It may be difficult or even 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. The total cargo capacity of the network is limited by the hub's capacity. Delays at the hub (such as from bad weather conditions) can result in delays throughout the network.
- Cargo must pass through the hub before reaching its destination and so require longer journeys than direct point-to-point trips. That may be desirable for freight, which can benefit from sorting and consolidating operations at the hub, but it is problematic for time-critical cargo as well as for passengers.
- Two trips are required to reach most destinations. The distance traveled may thus be several times longer compared to a direct trip between departure and destination points. The time spent at the hub and spending increases the duration of the journey. Moreover, missing the connecting bus, flight, or train may be more troublesome than just a delay.
In 1955, Delta Air Lines pioneered the hub and spoke system at its hub in Atlanta, Georgia, in an effort to compete with Eastern Air Lines. In the mid-1970s FedEx adopted the hub and spoke model for overnight package delivery. After the airline industry was 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 them. That reduces the need to travel long distances between nodes near one another. Another method is to use focus cities to implement point-to-point service for high-traffic routes and to bypass the hub entirely.
The spoke-hub model is applicable to other forms of transportation as well:
- Sea transport in which feeder ships transport shipping containers from different ports to a central container terminal to be loaded onto larger vessels.
- Cargo airliness: most UPS Airlines flights travel through its Worldport at Louisville International Airport, and many FedEx Express parcels are processed at its "SuperHub" at Memphis International Airport.
- Freight rail transport in which cargo is hauled to a central exchange terminal. At the terminal, shipping containers are loaded from one freight car to another, and classification yards (marshalling yards) are used to sort freight cars into trains and divide them according to varying destinations.
- Public transit uses various transport hubs 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.
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, theorized about industrial districts, with a number of key industrial firms and facilities acting 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.
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. The system constructs a dominant bilateral security architecture in East Asia that is different from the multilateral security architecture in Europe. The US acts as a "hub," and Asian countries like South Korea, Taiwan, and Japan are its "spokes." There is a strong alliance between the hub and the spoke, but there are no firmly established connections between the spokes themselves.
This system was famously inspired by John Foster Dulles, the US Secretary of State from 1953 to 1959. He used the term twice in Tokyo and once at the San Francisco Peace Treaty of September 1951, which led to talks for bilateral peace treaty between the US and Japan.
The 1951 Security Treaty Between the United States and Japan, the 1953 U.S.-South Korea Status of Forces Agreement and the 1954 Sino-American Mutual Defense Treaty (later replaced by the Taiwan Relations Act) are some examples of such bilateral relations.
In April 2014, all ten ASEAN defense chiefs and United States Secretary of Defense Chuck Hagel attended the US-ASEAN Defense Forum in Hawaii. That was the first time the US hosted the forum. It was part of a US attempt to get the countries to strengthen military ties between themselves.
- Hubs and Nodes
- Roundabout (traffic circle)
- Foreign policy of the United States for an example of international coordination through a third country.
- Point-to-point transit (alternate shipping model)
- Delta Air Lines Newsroom - Press Kit. Delta.com. Retrieved on 2013-08-16.
- Cha, V. D. (2010). "Powerplay: Origins of the U.S. Alliance System in Asia". International Security. 34 (3): 158–196. doi:10.1162/isec.2010.34.3.158.
- Hemmer, C.; Katzenstein, P. J. (2002). "Why is There No NATO in Asia? Collective Identity, Regionalism, and the Origins of Multilateralism". International Organization. 56 (3): 575–607. doi:10.1162/002081802760199890. JSTOR 3078589.
- Keck, Zachary (2 April 2014). "US Swears Asia Pivot Isn't Dead". thediplomat.com. The Diplomat. Retrieved 3 April 2014.
- Badcock, B. A., 2002, Making Sense of Cities: A Geographical Survey, London: Arnold, pp. 63–94.
- Lawrence, H., 2004, "Aviation and the Role of Government", London: Kendall Hunt, pp. 227–230.
- Markusen, A (1996). "Sticky Places in Slippery Space: A Typology of Industrial Districts". Economic Geography. 72: 293–313. doi:10.2307/144402.