Environmental assessment for non-prescribed infrastructure development projects: a case study in Bangkok Metropolitan

Rapid urbanization and urban growth have caused serious environmental problems in most cities of developing countries. Many infrastructure projects on varying scales have been implemented to meet the growing demands of such cities, but only a few are subjected to environmental impact assessment as part of the project approval process. In an attempt to justify environmental assessment (EA) for all infrastructure development projects (IDPs), irrespective of their scales, this paper investigates the environmental effects of large, medium and small IDPs implemented in urban fringe areas to understand and compare the nature of their impacts. The survey results show that respondents' perceptions of physical environment pertaining to air quality and noise were similar regardless of the scale of the project. However, in terms of vibration, surface water quality and ground water quality, the respondents' perceptions differed between large projects and small or medium projects. In order to avoid such negative impacts from IDPs in the future, this study proposes a mechanism for integrating EA into the planning and development control processes of local authorities.