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View from above of a city

Urban density: Promoting sustainable development – Part 2

Compact cities offer residents improved levels of access to services and economic opportunity. But over-densification can be damaging to health and wellbeing, and lead to the marginalisation of vulnerable communities.

Organisation for Economic Co-operation and Development (OECD)
8 April 2021

Cities tend to promote compact city development with a hierarchy of higher density and mixed-use clusters around public transport nodes. These strategies normally involve the redevelopment of areas in proximity to major transit stations. They intend to maximise access to transit through land use planning and community development policies. Examples can be found in cities such as London, Milan, Stuttgart and the Île-de-France region around Paris. This is because the most significant influence on transit seems to be proximity to public transport. The neighbourhood around the stations is an essential part of the life of the city as the station is the link between public transport and the city. When a new public transport service is provided in a neighbourhood, it has an impact on the neighbourhood’s functioning and planning.

Cities such as London consider that land around stations provides opportunities to create high-density, mixed-use places that are well connected to local amenities, and jobs and locations further afield. This is a way to make the most of past public transport investment and the benefits of any future investment by providing new homes and jobs nearby. In the Île-de-France region, France, the development of the Grand Paris project places the station at the centre of urban development. Other examples include Denmark’s Planning Act which requires any new offices over 1,500m² to be located within 600 metres of a rail station contributing to Copenhagen’s compact urban form. Korean cities have also explored the integration of land use policy and transport policies to build more compact cities and make better use of available land, particularly as they face critical urban challenges such as demographic change and access to affordable housing.

Denmark’s Planning Act requires any new offices over 1,500m² to be located within 600 metres of a rail station.

Urban redevelopment strategies are essential for the promotion of densification. It is commonly accepted that certain levels of density could contribute to economic growth due to increased agglomeration. Deteriorated buildings or areas could be repurposed for housing or other cultural or leisure activities boosting the economic activity of the area. But accessibility considerations should be part of the initiatives to make them effective. Public transport is a key component of policies intended to revitalise, regenerate and support growth in deprived areas. People living in deprived areas most of the time rely on walking or public transport, when provided, for accessing jobs, goods and services. If public spaces and transport are undeveloped, they will have limited access to socio-economic opportunities. Co-ordinating investment in public transport and redevelopment projects has the potential of increasing access to opportunities and contribute to well-being.

Research suggests that excessive densification could reduce proximity and increase travel. The problem is that building more housing may increase economic returns for land use, but it may also crowd out less intensive land uses such as public meeting places, recreational areas, schools, etc. The need for new housing and related densification may threaten the quality of public spaces such as urban parks, green areas and playgrounds. Moreover, as has happened in some cities such as Prague and Vancouver, a side effect of densification is that it may exclude economically vulnerable groups. The reason is that a new high standard of housing may be relatively expensive to buy or rent for low-income households, which could be forced to move to peripheral areas with cheaper housing. In this case, these groups may not have the same access to goods and services as those living in central areas. The renovation of older housing near central areas well served by public transport may also create gentrification and exclude some low-income residents.

The need for new housing and related densification may threaten the quality of public spaces. Moreover, a side effect of densification is that it may exclude economically vulnerable groups.

Research has found an overarching trend in the decline of population and built-up densities in cities across the world. According to OECD studies, “Despite growing populations and pressures on the housing market of many cities, little densification has occurred in recent decades in most urban areas in the OECD.” However, this decline varies across income groups, city sizes and regions.

A common misconception about density is that it requires high-rise buildings configured in close proximity to each other. This is the case in many Asian cities, particularly in the People’s Republic of China, that rely on the vertical expansion of built-up areas. Multiple land use configurations can lead to the same levels of density. High population density does not necessarily mean high-rise buildings. One key point of consideration is that accessibility should focus on making everyday life easier for residents. Therefore, since most new buildings are inserted into already defined land uses, to make everyday life simpler would entail adding complementary activities that add value. The challenge here is to focus on residents’ needs rather than only on the availability of land to build and promote activities that may not be in line with residents’ priorities.