Urban planners aim to eliminate slums—with computer programs

Cities across the globe are exploding in size. Some 4 billion people—more than half the world’s population—now live in urban areas, and the number is expected to reach 6.4 billion by 2050. The problem with such rapid growth is that when cities fill up or become too expensive, new residents are forced to settle in slums, which lack access to water, sanitation, emergency services, and hospitals. Now, scientists have come up with a way to redesign these underserviced areas, using a computer program that takes a mathematical approach to urban planning.

Called topology, the new approach maps out residents’ access to vital roads and city services as a spatial network. Places—like buildings and open spaces—represent the nodes of the network, and roads and paths represent the network connections. By designing an algorithm to model these access networks, the researchers were able to determine where new roads were needed to maximize access and minimize disruption to existing residents, the team reports today in Science Advances.

The researchers tested their approach in two slums—one in Cape Town, South Africa, and another in Mumbai, India. There, they worked with locals to gather data, run the algorithm, and decide—based on the data—where they wanted their new roads to be. They then sent their proposals to government officials.

Because the new topological approach doesn’t depend on the gridlike geometry of most city layouts, it can be used to analyze neighborhoods in almost any urban area—from Las Vegas, Nevada, to Harare. The scientists hope their research will help city officials work with local communities to eliminate existing slums—and prevent the creation of new ones.