Rethinking Urban Sprawl

As the world’s cities are growing, urban sprawl is getting worse. An new OECD study of 1,100 cities shows 60% of space is now low-density. This erratic city growth is damaging the environment. What can policy makers and governments do to move towards more sustainable cities?

This report provides a new perspective to the nature of urban sprawl and its causes and environmental, social and economic consequences. This perspective, which is based on the multi-dimensionality of urban sprawl, sets the foundations for the construction of new indicators to measure the various facets of urban sprawl.

The report uses new datasets to compute these indicators for more than 1100 urban areas in 29 OECD countries over the period 1990-2014. It then relies on cross-city, country-level and cross-country analyses of these indicators to provide insights into the current situation and evolution of urban sprawl in OECD cities. In addition, the report offers a critical assessment of the causes and consequences of urban sprawl and discusses policy options to steer urban development to more environmentally sustainable forms.

Cities are home to more than half of the world’s population and are the engines of economic growth and employment. However, cities also face major environmental, economic and social challenges, many of which are associated with the fact that urban development has occurred.

Urban sprawl, a particular form of development, is often cited as a driver of several of these challenges, including greenhouse gas emissions, air pollution, road congestion and lack of affordable housing.

• What exactly is urban sprawl and how can it be measured?
• Are cities in OECD countries sprawling and how is this impacting the environment?

Key Messages

• Urban sprawl, a particular form of urban development, is a driver of several major challenges facing cities. These challenges include greenhouse gas emissions, air pollution, road congestion and lack of affordable housing.
• Urban sprawl is a complex phenomenon, which goes beyond average population density. Its different dimensions reflect how population density is distributed across urban space and how fragmented urban land is.
• In most of the 29 OECD countries examined, cities have become more fragmented since 1990 and the share of land allocated to very low density areas has increased. While urban areas have become denser on average, today 60% of urban space is sparsely populated.
• Urban form is generally evolving in a way that induces higher car dependency and longer commuting distances. Such a development pattern implies more traffic jams, higher greenhouse gas emissions and more air pollution. It also substantially increases the per-user costs of providing public services that are key for well-being, such as water,
  energy, sanitation and public transport.
• Coherent and targeted policy action is urgently needed from different levels of government to steer urban development towards more sustainable pathways. This is also pivotal for achieving the goals of the Paris Climate Agreement and the UN Sustainable Development Goals.
• Policy action should focus on appropriately pricing car travel and parking, as well as investing in infrastructure for public and non-motorised transport. Parallel efforts are required to reform land-use policies which fuel urban sprawl.
• Policy makers should reconsider maximum density restrictions, revisit the design of urban containment policies and develop new market-based instruments to promote densification where it is most needed.
• With 7 in 10 people forecast to live in cities by 2050, we must act today to build better cities for better lives.