Sustainability and Urban Public Transportation

An analysis of data of the past few decades from cities around the world indicates that history is repeating itself. Although there are significant differences in socioeconomic and technological characteristics among these cities, a remarkable similarity exists in trends in urban transportation. The current growth in the use of automobiles in many cities of developing countries follows similar trends experienced in the United States and other developed countries several decades earlier. Even though there is much awareness and knowledge about sustainability, private vehicle ownership, and use continue to grow at an increasing pace with rising personal incomes and desires to experience faster and more reliable transportation technology. Urban density, expressed in number of people and/or jobs per unit of land, is the key indicator of the level of automobile ownership and use, and of associated parameters of sustainability. As personal incomes rise, choice of residential and job location increases, causing a decrease in urban density and affecting the relative use of private transportation and public transit. There are policy options related to land use, pricing, and technological factors that can have far reaching influence on the long-term sustainability of urban-transportation systems around the world. The basic implication of the analysis is that urban-transportation sustainability can be greatly enhanced if there are profound changes in urban structures and activities that can slow or reverse the growth in the use of private automobiles and can make transit and other modes attractive and viable.