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Transport economics is a branch of economics founded in 1959 by American economist John R. Meyer that deals with the allocation of resources within the transport sector. It has strong links to civil engineering. Transport economics differs from some other branches of economics in that the assumption of a spaceless, instantaneous economy does not hold. People and goods flow over networks at certain speeds. Demands peak. Advance ticket purchase is often induced by lower fares. The networks themselves may or may not be competitive. A single trip (the final good, in the consumer's eyes) may require the bundling of services provided by several firms, agencies and modes. Although transport systems follow the same supply and demand theory as other industries, the complications of network effects and choices between dissimilar goods (e.g. car and bus travel) make estimating the demand for transportation facilities difficult. The development of models to estimate the likely choices between the such goods involved in transport decisions (discrete choice models) led to the development of an important branch of econometrics, as well as a Nobel Prize for Daniel McFadden. In transport, demand can be measured in number of journeys made or in total distance traveled across all journeys (e.g. passenger-kilometers for public transport or vehicle-kilometers of travel (VKT) for private transport). Supply is considered to be a measure of capacity. The price of the good (travel) is measured using the generalised cost of travel, which includes both money and time expenditure. The effect of increases in supply (i.e. capacity) are of particular interest in transport economics (see induced demand), as the potential environmental consequences are significant (see ''externalities'' below). == Externalities == In addition to providing benefits to their users, transport networks impose both positive and negative externalities on non-users. The consideration of these externalities - particularly the negative ones - is a part of transport economics. Positive externalities of transport networks may include the ability to provide emergency services, increases in land value, and agglomeration benefits. Negative externalities are wide-ranging and may include local air pollution, noise pollution, light pollution, safety hazards, community severance and congestion. The contribution of transport systems to potentially hazardous climate change is a significant negative externality which is difficult to evaluate quantitatively, making it difficult (but not impossible) to include in transport economics-based research and analysis. Congestion is considered a negative externality by economists. An externality occurs when a transaction causes costs or benefits to third party, often, although not necessarily, from the use of a public good. For example, manufacturing or transportation cause air pollution imposing costs on others when making use of public air. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「transport economics」の詳細全文を読む スポンサード リンク
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