Downs–Thomson Paradox
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Downs–Thomson Paradox
The Downs–Thomson paradox (named after Anthony Downs and John Michael Thomson), also known as the Pigou–Knight–Downs paradox (after Arthur Cecil Pigou and Frank Knight), states that the equilibrium speed of car traffic on a road network is determined by the average door-to-door speed of equivalent journeys taken by public transport. It is a paradox in that improvements in the road network will not reduce traffic congestion. Improvements in the road network can make congestion worse if the improvements make public transport more inconvenient or if they shift investment, causing disinvestment in the public transport system. Consequence The general conclusion, if the paradox applies, is that expanding a road system as a remedy to congestion is ineffective and often even counterproductive. That is known as Lewis–Mogridge position and was extensively documented by Martin Mogridge in the case study of London on his 1990 book ''Travel in towns: jam yesterday, jam today and jam ...
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Anthony Downs
Anthony Downs (November 21, 1930October 2, 2021) was an American economist specializing in public policy and public administration. His research focuses included political choice theory, rent control, affordable housing, and transportation economics. He wrote a number of books including, ''An Economic Theory of Democracy'' (1957) and ''Inside Bureaucracy'' (1967), which have been major influences on the public choice school of political economy. In ''Downs's Law of Peak-Hour Traffic Congestion'' (1962), he accurately predicted that expanding expressways could not reduce traffic congestion, since demand would increase as well, and that reducing speeds increases capacity. He served as a senior senior fellow at the Brookings Institution in Washington, D.C., member of faculty at the University of Chicago and a visiting fellow at the Public Policy Institute of California in San Francisco. Early life James Anthony Downs was born on November 21, 1930, in Evanston, Illinois. His f ...
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Transport Network
A transport network, or transportation network, is a network or graph in geographic space, describing an infrastructure that permits and constrains movement or flow. Examples include but are not limited to road networks, railways, air routes, pipelines, aqueducts, and power lines. The digital representation of these networks, and the methods for their analysis, is a core part of spatial analysis, geographic information systems, public utilities, and transport engineering. Network analysis is an application of the theories and algorithms of graph theory and is a form of proximity analysis. History The applicability of graph theory to geographic phenomena was recognized as an early date. In fact, many of the early problems and theories undertaken by graph theorists were inspired by geographic situations, such as the Seven Bridges of Königsberg problem, which was one of the original foundations of graph theory when it was solved by Leonhard Euler in 1736. In the 1970s, the co ...
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Road Transport
Road transport or road transportation is a type of transport using roads. Transport on roads can be roughly grouped into the transportation of goods and transportation of people. In many countries licensing requirements and safety regulations ensure a separation of the two industries. Movement along roads may be by bike, automobile, bus, truck, or by animal such as horse or oxen. Standard networks of roads were adopted by Romans, Persians, Aztec, and other early empires, and may be regarded as a feature of empires. Cargo may be transported by trucking companies, while passengers may be transported via mass transit. Commonly defined features of modern roads include defined lanes and signage. Various classes of road exist, from two-lane local roads with at-grade intersections to controlled-access highways with all cross traffic grade-separated. The nature of road transportation of goods depends on, apart from the degree of development of the local infrastructure, the distance ...
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Jevons Paradox
In economics, the Jevons paradox (; sometimes Jevons effect) occurs when technological progress or government policy increases the efficiency with which a resource is used (reducing the amount necessary for any one use), but the falling cost of use increases its demand, increasing, rather than reducing, resource use. The Jevons' effect is perhaps the most widely known paradox in environmental economics. However, governments and environmentalists generally assume that efficiency gains will lower resource consumption, ignoring the possibility of the effect arising. In 1865, the English economist William Stanley Jevons observed that technological improvements that increased the efficiency of coal use led to the increased consumption of coal in a wide range of industries. He argued that, contrary to common intuition, technological progress could not be relied upon to reduce fuel consumption. The issue has been re-examined by modern economists studying consumption rebound effects f ...
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Marchetti's Constant
Marchetti's constant is the average time spent by a person for commuting each day. Its value is approximately one hour, or half an hour for a one-way trip. It is named after Italian physicist Cesare Marchetti, though Marchetti himself attributed the "one hour" finding to transportation analyst and engineer Yacov Zahavi. Marchetti posits that although forms of urban planning and transport may change, and although some live in villages and others in cities, people gradually adjust their lives to their conditions (including location of their homes relative to their workplace) such that the average travel time stays approximately constant. Ever since Neolithic times, people have kept the average time spent per day for travel the same, even though the distance may increase due to the advancements in the means of transportation. In his 1934 book ''Technics and Civilization'', Lewis Mumford attributes this observation to Bertrand Russell: :Mr. Bertrand Russell has noted that each improvemen ...
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Induced Demand
In economics, induced demand – related to latent demand and generated demandSchneider, Benjamin (September 6, 2018"CityLab University: Induced Demand"''CityLab'' – is the phenomenon whereby an increase in supply results in a decline in price and an increase in consumption. In other words, as a good or service becomes more readily available and mass produced, its price goes down and consumers are more likely to buy it, meaning that demand subsequently increases. This is consistent with the economic theory of supply and demand. In transportation planning, induced demand, also called "induced traffic" or consumption of road capacity, has become important in the debate over the expansion of transportation systems, and is often used as an argument against increasing roadway traffic capacity as a cure for congestion. Induced traffic may be a contributing factor to urban sprawl. City planner Jeff Speck has called induced demand "the great intellectual black hole in city plan ...
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Central London
Central London is the innermost part of London, in England, spanning several boroughs. Over time, a number of definitions have been used to define the scope of Central London for statistics, urban planning and local government. Its characteristics are understood to include a high density built environment, high land values, an elevated daytime population and a concentration of regionally, nationally and internationally significant organisations and facilities. Road distances to London are traditionally measured from a central point at Charing Cross (in the City of Westminster), which is marked by the statue of King Charles I at the junction of the Strand, Whitehall and Cockspur Street, just south of Trafalgar Square. Characteristics Definitions London Plan The London Plan defines the 'Central Activities Zone' policy area, which comprises the City of London, most of Westminster and the inner parts of Camden, Islington, Hackney, Tower Hamlets, Southwark, Lambeth, Kensington ...
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Rapid Transit
Rapid transit or mass rapid transit (MRT), also known as heavy rail or metro, is a type of high-capacity public transport generally found in urban areas. A rapid transit system that primarily or traditionally runs below the surface may be called a subway, tube, or underground. Unlike buses or trams, rapid transit systems are railways (usually electric railway, electric) that operate on an exclusive right-of-way (transportation), right-of-way, which cannot be accessed by pedestrians or other vehicles, and which is often grade-separated in tunnels or on elevated railways. Modern services on rapid transit systems are provided on designated lines between rapid transit station, stations typically using electric multiple units on rail tracks, although some systems use guided rubber tires, magnetic levitation (''maglev''), or monorail. The stations typically have high platforms, without steps inside the trains, requiring custom-made trains in order to minimize gaps between train a ...
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Induced Demand
In economics, induced demand – related to latent demand and generated demandSchneider, Benjamin (September 6, 2018"CityLab University: Induced Demand"''CityLab'' – is the phenomenon whereby an increase in supply results in a decline in price and an increase in consumption. In other words, as a good or service becomes more readily available and mass produced, its price goes down and consumers are more likely to buy it, meaning that demand subsequently increases. This is consistent with the economic theory of supply and demand. In transportation planning, induced demand, also called "induced traffic" or consumption of road capacity, has become important in the debate over the expansion of transportation systems, and is often used as an argument against increasing roadway traffic capacity as a cure for congestion. Induced traffic may be a contributing factor to urban sprawl. City planner Jeff Speck has called induced demand "the great intellectual black hole in city plan ...
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Computer Network
A computer network is a set of computers sharing resources located on or provided by network nodes. The computers use common communication protocols over digital interconnections to communicate with each other. These interconnections are made up of telecommunication network technologies, based on physically wired, optical, and wireless radio-frequency methods that may be arranged in a variety of network topologies. The nodes of a computer network can include personal computers, servers, networking hardware, or other specialised or general-purpose hosts. They are identified by network addresses, and may have hostnames. Hostnames serve as memorable labels for the nodes, rarely changed after initial assignment. Network addresses serve for locating and identifying the nodes by communication protocols such as the Internet Protocol. Computer networks may be classified by many criteria, including the transmission medium used to carry signals, bandwidth, communications pro ...
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Arthur Cecil Pigou
Arthur Cecil Pigou (; 18 November 1877 – 7 March 1959) was an English economist. As a teacher and builder of the School of Economics at the University of Cambridge, he trained and influenced many Cambridge economists who went on to take chairs of economics around the world. His work covered various fields of economics, particularly welfare economics, but also included Business cycle theory, unemployment, public finance, index numbers, and measurement of national output.Nahid Aslanbeigui, 2008. "Pigou, Arthur Cecil (1877–1959)," ''The New Palgrave Dictionary of Economics'', 2nd edAbstract./ref> His reputation was affected adversely by influential economic writers who used his work as the basis on which to define their own opposing views. He reluctantly served on several public committees, including the Cunliffe Committee and the 1919 Royal Commission on Income tax. Early life and education Pigou was born at Ryde on the Isle of Wight, the son of Clarence George Scott Pigou, ...
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Braess's Paradox
Braess's paradox is the observation that adding one or more roads to a road network can slow down overall traffic flow through it. The paradox was discovered by the German mathematician Dietrich Braess in 1968. The paradox may have analogies in electrical power grids and biological systems. It has been suggested that, in theory, the improvement of a malfunctioning network could be accomplished by removing certain parts of it. The paradox has been used to explain instances of improved traffic flow when existing major roads are closed. Discovery and definition Dietrich Braess, a mathematician at Ruhr University, Germany, noticed the flow in a road network could be impeded by adding a new road, when he was working on traffic modelling. His idea was that if each driver is making the optimal self-interested decision as to which route is quickest, a shortcut could be chosen too often for drivers to have the shortest travel times possible. More formally, the idea behind Braess's di ...
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