Transportation system sustainability issues in high-, middle-, and low-income economies : Case studies from georgia (U.S.), South Korea, Colombia, and Ghana

While there is no standard definition for sustainable transportation, several adopted definitions reflect that a sustainable transportation system should be effective and efficient in providing safe and equitable access to basic economic and social services, promote economic development and support environmental integrity. Critical priorities, standards, and constraints for attaining sustainable transportation may be different, however, in different countries depending on prevailing socioeconomic conditions and political and administrative institutions. This study develops four case studies to characterize some of the major transportation system sustainability issues in developed and developing economies. The cases demonstrate that while transportation sustainability issues revolve around similar issues, the actual process of identifying and addressing pertinent issues to promote transportation system sustainability may involve widely different priorities and constraints that should influence how standards are developed to promote successful movement toward sustainability in the international community.