Source: adapted from Barter, P.A. (2004) A Broad Perspective on Policy Integration for Low Emissions Urban Transport in Developing Asian Cities. Draft paper for the International workshop Policy Integration towards Sustainable Energy Use for Asian Cities: Integrating Local Air Pollution and Greenhouse Gas Emissions Concerns. Institute for Global Environmental Strategies, Kanagawa.
- (A) Automobile dependency. This development path leads to the setting of automobile dependent cities with investment continuously made in motorization and the development of a road and highway system. The first step usually involves the diffusion of non-motorized forms of transportation, particularly the bicycle. This was the case of cities in developed economies in the late 19th and early 20th century and of Asian cities (particularly China) in the 1970s. At this stage, a path divergence (1) is likely to take place towards the setting of public transit services. However, a path followed in several developing economies concerns a further motorization with the motorcycle as an intermediary form, which leads to cities saturated with motorcycles, buses and some automobiles. As road infrastructure investment continues and with economic development, the outcome is a car-oriented city where the automobile accounts for the majority of passengers movements. Such an outcome can also be achieved by cities that initially undertook transit developments but through a path divergence (3) moved towards automobile dependency through the abandonment of several transit services or the lack of further developments in public transit. This was particularly the case for North American cities such as Los Angeles and Houston.
- (B) Transit-oriented development. This development path involves slow levels of motorization and moderate road building. Through massive investments in public transit and transit-oriented land use development strategies, this path leads to the setting of transit cities where the bulk of the population uses public transit to satisfy their mobility requirements. Such cities are however not that common because as many cities undertook development, an additional path was followed, which lead to the development of hybrid cities.
- (C) Hybrid cities. This development path is the outcome of further motorization, but the pace of road development comes faster than the pace of urban transit development. It eventually leads to a saturation of the transport system with buses and automobiles. This situation characterized many cities in developed economies in the second half of the 20th century. A possible path divergence involves a rapid motorization and a move towards automobile dependency (3). Alternatively, through restrictions on the use and ownership of the automobile and the development of alternative modes of transportation, a path divergence can be achieved (2), leading to more transit oriented forms.