Dr. Patrick Lamson-Hall
Africa is experiencing unprecedented urban growth, and how we manage that growth will define the future of the continent. By 2050, Africa’s urban population will increase by 800 million people, with much of this expansion occurring in rapidly growing "secondary cities." Many cities are already experiencing exponential growth, with their populations surging as rural residents seek better lives and new livelihoods.
Recent research shows that the area of a typical Sub-Saharan African city has tripled in size between 1990 and 2014, while the urban population has doubled. By 2050, Africa’s urban population is expected to triple, with a majority of its residents living in cities. The explosive growth in urban area that will accompany population growth presents enormous challenges, but also tremendous opportunities if it is planned correctly.
Urban expansion planning offers a straightforward yet powerful solution to these problems by proactively organizing the urban peripheries of cities to accommodate future populations, ensuring access to infrastructure, and promoting environmental sustainability. This approach prevents chaotic sprawl and allows cities to accommodate their booming populations in a more organized and sustainable way. Implemented correctly, it fosters economic development, improves access to services, and reduces inequality.
Traditional urban planning often focuses on ambitious, large-scale master plans that are costly, complex, and difficult to implement—especially in developing contexts. By contrast, urban expansion planning offers a simple, scalable, and cost-effective solution that focuses on three key elements: expanding city boundaries, securing land for a grid of arterial roads, and protecting environmentally sensitive spaces. This strategy draws from lessons learned from successful urban expansion efforts in cities like New York and Barcelona in the 19th century. In New York the Commissioners' Plan of 1811 expanded the city’s buildable area seven-fold, setting the stage for its population and economic boom over the following decades.
Today, the same principles can be applied to rapidly growing cities across Africa. Since 2013, the Urban Expansion Initiative, led by a team from New York University, has worked with secondary cities in Ethiopia and Colombia training local officials and helping them implement urban expansion plans on the ground. The Cities Alliance has also embraced the approach, supporting several additional Ethiopian cities and cities in Uganda and Somalia.
Work begins by projecting population growth for the next 30 years and expanding city boundaries to encompass this growth. Then, the focus shifts to planning a grid of arterial roads—essential infrastructure that ensures every future household will be connected to transportation networks and public services. Finally, the city works to protect the land for the arterial grid along with large environmentally sensitive areas.
By prioritizing these basic, essential steps, cities can grow in a more organized and efficient manner, setting the stage for long-term prosperity.
Preventing Unplanned Informality: Planning the Urban Periphery
Mekele Area growth 2016-2020
One of the most significant challenges in rapidly urbanizing cities is the proliferation of informal settlements on the periphery. These settlements emerge without any formal planning and often lack basic infrastructure and legal recognition. The result is sprawling, disorganized areas that are difficult and costly to integrate into the broader urban landscape, leaving residents disconnected from essential services and economic opportunities.
Urban expansion planning offers a solution to this problem by ensuring that land on the urban periphery is properly laid out and connected to the existing city before informal settlements develop. In Ethiopian cities like Bahir Dar and Mekele, this approach has proven highly effective: By establishing a network of arterial roads and securing space for public services, cities can guide the growth of the periphery in a way that is organized, efficient, and inclusive.
At its core, urban expansion planning is about creating cities that work for everyone. By focusing on basic infrastructure—roads, public spaces, and essential services—cities can lay the groundwork for sustained economic growth. Planned cities are more accessible, allowing residents to move more freely between home, work, and other services. This mobility is key to fostering functional metropolitan labor markets, which are crucial for economic development.
In Ethiopia, households in planned areas have seen significant improvements in their quality of life. They are four times more likely to have access to formal land tenure, piped drinking water, and electricity compared to households in informal settlements. Additionally, their access to the city center has improved dramatically, with commute times reduced by one-third and transportation costs lowered by nearly 50%. Incomes in those areas are 10% - 15% higher on average after controlling for education and other socioeconomic factors. These improvements don’t just benefit individual households—they also create a more dynamic and productive urban economy.
Moreover, urban expansion planning can help municipalities increase their revenue by formalizing new neighborhoods and integrating them into the tax system. This, in turn, allows local governments to reinvest in infrastructure and services, creating a positive feedback loop of growth and development.
As cities across Africa grow, they face increasing environmental pressures, from deforestation to rising greenhouse gas emissions. Without proper planning, urban sprawl can exacerbate these issues, leading to more car-dependent cities, increased emissions, and greater environmental degradation. Urban expansion planning addresses these concerns by promoting more compact, connected urban forms that encourage public transportation, cycling, and walking.
The road grids established through urban expansion planning ensure that no household is more than 500 meters from an arterial road, making it easier for residents to use public transportation instead of relying on private vehicles. It also reduces vehicle kilometers traveled by promoting compact growth, and the robust network reduces traffic congestion, lowering fuel consumption. Studies have shown that cities with well-planned road networks can reduce vehicle kilometers traveled and lower emissions by up to 17%.
In addition, urban expansion planning emphasizes the protection of environmentally sensitive areas, such as wetlands, riverbanks, and public open spaces. By safeguarding these areas early in the planning process, cities can reduce the risk of flooding, heat islands, and other environmental challenges. Protecting these spaces also improves livability, creating green areas for recreation and enhancing the overall quality of life for residents.
The challenges facing African cities are immense, but so are the opportunities. With urban populations expected to triple by 2050, cities have a limited window of time to plan for future growth and ensure that their expansion is sustainable, inclusive, and economically beneficial. The success of urban expansion planning in Ethiopia demonstrates that it is possible to manage rapid urbanization in a way that benefits both residents and the environment.
Urban expansion planning is not a panacea for all the challenges of urbanization, but it is a vital tool that cities can use to lay the groundwork for a prosperous future. By prioritizing simple, scalable solutions like road grids and the protection of open spaces, African cities can grow in an organized, sustainable manner that improves the quality of life for all residents. The time to act is now—before the window of opportunity closes and the challenges of urbanization become too costly to reverse.
