Lo sviluppo della mobilità sotterranea in Asia: le linee metropolitane di Shanghai e Tokyo

Urbanization has been occurring in the industrialized Western nations for more than two hundred years, but today the phenomenon is taking place so rapidly, especially in the developing countries, that cities need to face complex challenges to preserve their growth and livability: urban problems such as congestion, pollution and sprawl are putting a strain on administrators and policy makers to provide the necessary infrastructures to new citizens, with a sustainable approach. Therefore, in many cities much effort has been focused on public transport, especially the underground. Thus, in a large number of Asian metropolis, where air pollution levels dramatically exceed the sustainable limits and strong migration flows from rural areas reduce the availability of non-urbanized land, the development of an efficient underground transport network has become essential for the survival of the urban system. This paper provides a description of two metro systems which stand out for the length – Shanghai Metro System – and for the number of daily riderships – Tokyo Metro System – and which are both in Asia. The analysis shows the increasingly importance of urban underground space (UUS) for the sustainable growth of cities: this new resource is no longer used exclusively for transport, parking or for utilities like heating, water supply and sewerage, but it also includes commercial, entertainment and public activities, thus extending urban life from street level to underground levels.