In recent years, city planners, developers, and policymakers have increasingly looked towards designing a more ‘compact city’ in order to achieve a more sustainable urban form. There are many perceived benefits of the compact city over “urban sprawl”, including less car dependency (and, hence, lower emissions), reduced energy consumption, better public transportation services, increased overall accessibility, re-use of infrastructure and previously developed land, rejuvenation of existing urban areas and urban vitality, higher quality of life, the preservation of green space, and the creation of a milieu for enhanced business and trading activities (Thomas and Cousins 1996). However, the major findings of US mega-city research found that denser and more mixed land use
are associated with less automobile use for improving sustainability, and more creation of pedestrian areas in order to support the development of a “health city”. However, there is a limitation for Asian mega cities. Bangkok Mega-city also has been experiencing a rapid increase in automobile use, and empirical studies in the highdensity context have been scarce. The studies have shown that the process of urbanization presents enormous challenges for government, social and environmental planners, architects, and inhabitants of the city. There are three points, as follow: (1) What urban population should be realized to mega-city growth? (2) How should compact city policy and subcenter policy6 serve as guidelines for the mega-city? And (3) how should the urban population commute in order to carry out urban activities in the mega-city?