Megacities and High Speed Rail systems : which comes first ?

A megacity is usually defined as a metropolitan area with a total population in excess of 10 million people. The number of megacities is increasing worldwide: in 1950 they were 4; in 1980 they were 28, in 2002 they were 39 and by 2015 they will be 59. In most agglomerations and megacities, urban planning and public infrastructure can guide the urban development in order to achieve a proper sustainable structure only partially. The extension of cities is in most cases in advance of urban development work and the provision of public facilities (Kotter, 2004). In Europe it is rare to find megacities, apart from London and Paris, both of them megacities for reasons other then the existence of High Speed Rail (HSR). However, due to the general high density of population in Europe and the short distance between medium and large cities there is the possibility of HSR potentiate the emergence of groups of cities that will be linked together and thus reap the economic benefits associated with megacities, namely economies of scale, economies of agglomeration and bigger labour markets. This is important because adequate levels of planning might help to avoid the disbenefits of megacities in these European megacities. However, in this contribution the authors argue that in some cases, specific facilities can foster the formation of megacities; in fact, this is the case of High Speed rail systems (see for example Europe). Specifically, High-Speed trains can be used to solve two different accessibility problems. In the first case, where a point-to-point link is dominant, each train is a potential substitute for an air connection between two cities, i.e. it connects cities (or rather CBDs) at long distance with a direct train connection (Blum et al., 1997).The HSR links between Paris and Lyon, Paris and London and, Tokyo and Osaka, could be seen as examples of this first type of train connection. In this case the train trip mobil.TUM 2012 International Scientific Conference on Mobility and Transport