In developed countries, sustainable development has become increasingly important due to increased public awareness and pressure to meet demand from population growth. Urban Form is defined by (RTPI, 2015) as “Physical characteristics that make up built-up areas, such as shape, size and density.”Â It can be classified into four categories: Centralisation, Decentralisation, Concentration and Sprawl(Holden, 2004). Compaction (Centralisation and concentration) has been an EU policy since 1992 hence most European cities are densely populated. The aim is to develop sustainability which is defined by the Brundtland Commission as “Meeting the needs of the present, without compromising the ability of future generation to meet their own needs.” This can be considered from four dimensions: Economic, Social, Natural and Political (UNESCO, 2010). The essay will first focus on the advantages and disadvantages of compaction in relation to different dimensions of sustainability, then focus on alternative forms. Finally, concluding the best option and consider future challenges.
Compaction will benefit cities economically due to the agglomeration effect where the concentration of firms allow them to benefit from the economies of scale hence reducing the cost of operation and the infrastructure cost. Also, it encourages more specialisation as higher density has higher demand which allows more division of labour (Tejvan, 2012). This means the population would have access to a wider range of services and job opportunities, hence more likely to receive a more reliable income and become economically sustainable. A compact city will make public transport more attractive as there is a higher demand and usage which allow prices to be more affordable and higher frequency services to be run. This will increase accessibility which allows access to more job opportunities and essential services (RTPI, 2015).
Socially, more people living closer together means that there is a higher chance that people are meeting with each other and communicate hence the chance of social exclusion is reduced and allow accumulation of social capital (Bramley et al., 2009).However, results from the survey suggest that medium density (Terraced Housing) is the best for social interaction. A higher density will have a negative effect. Compact living encourages mixed land use hence people would have easier access to services and job opportunities which will increase the quality of life and improve social sustainability. Finally, with reduced traffic volume as car ownership reduces, safety for pedestrians has increased especially with pedestrianisation schemes of centres making them vibrant again. Urban sprawl has been the strategy in most UK cities between the 1970s and 90s with the focus on out of town development (Williams, 2014).
As economic and business growth contradicts with environmental sustainability, therefore activities have to be regulated by the government through legislation and documents such as Planning Policy Guidance (PPG).Â The three main arguments of environmental sustainability are related to land use, energy use and air quality. Land use will reduce by increasing density through building on brownfield sites so the countryside is protected. In 1947, the Green Belt is introduced as part of the Town and Country Planning Act and PPG2 which allows local authorities to set areas where development is prohibited on the outskirt of towns and cities. By 2010, around 13% of land in England is Green Belt (Communities and Local Government, 2010). Another supportive reason is the air quality will improve because of compaction mainly due to reduced car ownership as people will travel less with services close to where they live and work. Energy cost and consumption are estimated to be reduced as a result of denser living.
However, there are a lot of argument and findings which suggest the benefit of compaction is over-emphasised. Because of the green belt, house prices have been unaffordable for many younger generation and lower income household. According to Halifax Bank since 1983, UK house prices has risen by 101% and 124% in London after taking into account of inflation (The Investor, 2012). The pressure to build more homes can be seen through the increase in approved planning permission to build on the green belt which rises from 2300 in 2009-10 to 12,000 in 2014-15 (Booth, 2017). The increase in house prices means that houses are segregated by income.Â Gentrification in the city centre can be seen in most UK cities where new houses are targeted for investors or the young affluent. People with lower income are forced to live in terrace housing outside of the city which are deprived and highly segregated by ethnic minorities which are both economically and socially unsustainable. The Green Belt also force development to occur outside it hence increasing urban sprawl(Mace et al., 2016). For example, a lot of people commute from areas such as Redhill and Horsham which are just outside the Metropolitan Green Belt. This is not good in terms of reducing land use. Finally, government focus on compaction means that rural areas are left isolated as investment focus on towns and cities(Frey, 2003). Many villages lack basic services such as post office as more people move into cities, there is not enough demand to keep them operating.
Compaction is also associated with an increase in stress level which will lead to poorer social ties in communities. The ease of access to shops and services means that time spent in the community is reduced and poorer safety perception due to distrust of neighbours and presence of more people. Hence (Bramley et al., 2009) found that residential satisfaction is low in compacted areas which is not socially sustainable.
As the land value increases in the city centre, this means the availability of green spaces is at a premium hence environmental quality will decline as most areas will be concrete. Although congestion is reduced is surrounding area, traffic volume in the centre actually increases which means air quality in the city centre is worse and increase chances of respiratory disease (Echenique et al., 2012). Melia et al (2011) suggest the idea of paradox of intensification where doubling the density does not reduce the number of trips by half. For example, Gordon (1997) cited in Melia et al (2011) found that in England that doubling densities only leads to 7% decrease in miles travel to work. This is mainly due to the population increase in the area.Studies have found that compaction might not lead to a reduction in energy use. (Heinonen et al., 2011) found that in Helsinki that CO2 emission is higher in downtown area than suburbs. They conclude that this is due to a higher standard of living in the downtown and the increase in emissions is more than the effect of compaction. These examples suggest the environmental benefits of compaction could be overstated.
An alternative urban form which can be considered is polycentric cities which are decentralised but concentrated. This is evolved from Howard’s idea of the Satellite or Garden City in the early 1900s where a centre city is surrounded by satellite cities which carry around 32,000 people each hence a medium density. These satellite cities are self-contained with services and workplace and connected with other cities by Rail links. It focuses on the symbiotic relationship with nature hence trying to achieve sustainability (Frey, 2003).Â It is very idealistic and only 2 garden cities were built in the UK which was not very successful as density is too low for self-sufficient economy and services.
Another form is the Transit Oriented Development (Calthorpe, 1993 cited in Frey, 2003) which based development around a centre with public transport Hub which has rail links with a major city. The centre is an area for the community with low rise apartments in centre and terraces further away. Parks will be located further away from the centre. This type of development is also known as corridor growth hence a controlled way to limit urban sprawl and Copenhagen’s Finger Plan is a good example (see Figure 1). People can live in medium densities towns which have shops and services near the hub and have easy access to the countryside hence a sustainable form. However, the high house prices in the centre is still problematic.
According to a study of 114 European Cities by Zoeteman et al (2016). It found that sustainability score of city improves up to 2 million inhabitants mainly due to economic sustainability. In cities that are larger than 250,000 people, ecological and social capital reduce. It concludes the ideal size of 100,000-250,000 inhabitants which is a medium density. Therefore, it seems that future growth strategy should focus on developing polycentric medium density cities which is well connected by Public Transport along with technological innovation to reduce environmental pollution. This is a compromise between a centralised compact city and dispersed development.
Current research shows that there is no consensus on whether compaction will benefit socially and environmentally. However, as most governments currently prioritise economic growth, the benefit of agglomeration means that compaction will likely to continue. Ideally, a polycentric network of medium density cities will achieve all forms of sustainability the best.
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