Urban planners in South Asia are frequently advised by Northern experts to make their settlements more densely populated if urban sustainability is to be achieved. But their task is formidable given that the world’s three most densely populated megacities, Dhaka, Mumbai and Karachi, are all in South Asia. The poor live together in high numbers surpassing all building byelaws and zoning regulations for these cities. The rules are often flouted, particularly in both informal and formal settlements where residents earn low incomes.

Results from IIED-supported density studies on Karachi, Bangkok, and Kathmandu, and additional research on Mumbai by Alain Bertaud, tell us a lot about the challenges the cities’ inhabitants face. 

Karachi, Pakistan’s largest city, has 2,280 people living per hectare of land. But this average figure masks the disparities in living conditions experienced by the city’s wealthiest and poorest inhabitants. While byelaws in Karachi permit a maximum density of 1,625 persons per hectare, parts of the inner city have more than 4,000 persons per hectare. In contrast, Karachi’s elite settlements have densities as low as 200 persons per hectare. This is due in part to large residential plots of more than 0.2 hectares. To put this in perspective, one family in an elite settlement lives on enough land to house 800 people if the land was occupied as densely as the city’s poorer areas.

Nepal’s capital city, Kathmandu, is also rapidly growing and densifying. In 2011, the city had an average density of 197 persons per hectare, while its inner city had a ward density of up to 1,181 people per hectare. If Kathmandu’s byelaws were strictly enforced, a sizeable portion of the inner city population would have to be removed. But this would only exacerbate the city’s affordable housing scarcity.

One of the main measures used by urban planners to analyse urban density is called the floor to ratio (FAR), the ratio of the footprint of an entire plot of land against the actual constructed area (which may be a building with many floors). According to Mumbai’s byelaws, the maximum residential FAR is 1:1.33. Yet, with 3,230 people living per hectare, the city’s density levels far exceed what these regulations would permit. This is especially the case in Dharvi, Mumbai’s largest slum, where density levels are as high as 44,460 people per hectare, according to a study by the Kamla Rajeja Vidyanidhi Institute of Architecture. 

These density levels could never have been achieved if the FAR had been strictly enforced. This is not surprising, however. Like many large cities, Mumbai’s regulatory framework was originally designed to strictly limit development in an effort to slow urban migration (even though most urban population growth is now attributed to natural increase). Such anti-urban policy frameworks ultimately fail to address the opportunities that urban growth presents for planning cities that are not only more prosperous and environmentally sustainable, but also more inclusive of the poorest and most vulnerable groups.

These groups typically live in slums and informal settlements, which accommodate more than 50 percent of the population of these cities. The exception is Kathmandu, where informal squatter settlements account for just 3-4 per cent of the city’s total population, but a significant share of its low-income populace. This number will continue to grow in this and other cities where population and land pressures are intensifying, but where inappropriate and anti-poor regulatory systems remain intact. As these settlements continue to grow, their densification can be particularly problematic where overcrowding is already an issue.

While the need to provide affordable housing on safe and secure land is urgent, significant challenges remain. Market pressures are increasingly driving low-income households (including many renters) from valuable inner-city locations, widespread speculation is preventing much needed land from being developed, and zoning byelaws and building regulations frequently impose unnecessary restrictions on development.

As settlements densify haphazardly, affordable housing in the informal sector is increasing, but living conditions, services and crowding are worsening. The disastrous consequences for risk-prone cities were starkly revealed when Kathmandu was struck by an earthquake on the 26^th of April 2015 followed by a second on the 12^th of May. Tellingly, around two-thirds of deaths were caused by building collapse, with low-income informal residents living in poorly constructed buildings bearing the brunt.

However, there are important benefits to be had from density. The study of Bangkok showed that upgraded settlements with higher densities are more desirable to residents than unimproved slums. This suggests that increasing densities can work when adequate infrastructure (e.g. water, sanitation, drainage, all weather roads and paths) and flexible housing designs are supported. Increasing densities can also work to enhance the efficiency of infrastructure provision and lower the cost of land, which can help to make settlements with adequate services more accessible to lower-income groups.

The IIED-supported studies of Karachi, Bangkok and Kathmandu present a number of lessons for reforming regulations so that they leverage density’s potential to realise these benefits. These lessons are organised under six main themes:

1. Enforceability and affordability – Reform regulatory systems to ensure they are adopted by private developers accustomed to evading regulations (in part because these regulations impose unnecessary restrictions on development) and affordable to low-income groups accustomed to living informally (in part because these groups cannot afford the costs of conforming to regulations)
2. Participation – Involve local non-governmental organisations with experience working with land owners, private developers and low-income groups to help determine the reforms required to make regulatory frameworks (including risk reduction measures) more appropriate and enforceable
3. Learning – Apply the lessons learnt from regulatory innovations deployed in upgraded informal settlements and land-pooling projects to the development of more appropriate and enforceable regulatory frameworks
4. Flexibility – Permit mixed land uses, small plot sizes and flexible housing designs (including incremental housing) to achieve neighbourhoods with more affordable housing and infrastructure, stronger community relations, and higher densities than high-rise apartment blocks
5. Land markets – Heavily fine land owners who leave their land vacant and undeveloped to reduce market distortions
6. Rental markets – Promote safe and secure rental markets by creating incentives (such as better loan facilities, tax rebates and other finance mechanisms) for low-income groups unable to access land and housing on their own

If these lessons can be applied, then municipal governments will have a better chance of addressing the need for safe and affordable housing in rapidly growing and densifying cities. This must necessarily include a stronger focus on guarding against anti-poor market forces and integrating affordable risk reduction measures into regulatory frameworks that are more likely to be followed by private developers and low-income groups.

For more information, visit the website www.urbandensity.org, which has recently been updated with new case studies, videos and publications exploring how tightly contained, heavily populated, shared spaces can be made to work best, for residents and for the natural systems that cities depend on.