The current rapid urbanization – especially in cities of the developing world – is bringing about many challenges in the spatial distribution of people and resources, as well as in the use and consumption of land. In some regions, urban land has grown much faster than the urban population, resulting in less dense and more inefficient land use patterns. Car-centred urban models are still the widespread norm, with strict zoning policies dividing urban space into residential, commercial, and industrial areas. These horizontally sprawling cities find it gradually harder to deal with an ever increasing urban population, and are not sustainable over the long-term, owing to overwhelming negative externalities such as congestion, infrastructure issues, pollution, and social disaggregation.
Largely due to the absence of urban planning strategies, frameworks, and coordination, population growth tends to result in large conurbations and urban sprawl, as residents spill from the core municipalities to occupy land in surrounding urban centres, often lacking accompanying services, amenities, and infrastructure. As a result, pressure on land and natural resources — as well as mobility and energy constraints — start to have a negative effect on the urban economy and overall efficiency of the city region.