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How High-Tech Maps Could Help Urban Slums Plan Better Streets

Open Reblock can help improve access to much-needed public services, like clean water and medical care.

Residents stand outside stilt homes over polluted water in a slum in Recife, Brazil. (AP Photo/Felipe Dana)

In slums, buildings are often so densely packed that many are cut off from streets and pathways. This creates a literal roadblock to much-needed public resources.

“In South Africa, governments will often say that informal settlements are too dense to install adequate services,” Charlton Ziervogel, deputy director at the Communities Organization Resource Centre, a Cape Town-based slum advocacy and support NGO, tells CityLab. “So you’ll find municipalities that install toilets, but only at the edge of a settlement, because they perceive that there is no space inside.”

It’s a serious matter. Across the global south, hundreds of millions live in slums lacking piped water, proper drainage, and sanitation—ideal breeding grounds for virus-carrying insects and other types of disease. To fight epidemics such as Zika, experts warn, living conditions for the urban poor must be improved. But to do so, many slum communities first need to open up space.

A new tool might help. Open Reblock is a free, open-source platform designed to simplify the process of thoughtfully reorganizing slum communities. Funded through OpenIDEO, it’s the product of a major research collaboration by the Santa Fe Institute, Sam Houston State University, UC Berkeley, and Shack/Slum Dwellers International, a global network of community-based organizations representing the urban poor.

The only input that’s required for Open Reblock is a good-quality map with details on each property inside a community and its access to the street network. The tool uses an algorithm to identify the least disruptive reorganization of a cluster of slum blocks so that each parcel gets access to the street—nudging this house two meters east, extending that road a few meters south. It produces a new map of this “reblocked” community, which residents can adjust to their needs and use to push local government (or other support sources) to begin construction.

“How to change the physical slum? You tap into the knowledge of the people who live in the slum,” says José Lobo, an economist and sustainability researcher with Arizona State University who has worked on the project. The tool, he says, captures that knowledge—physically, on a map—so it “can be shared, examined, revisited, and acted on while minimizing disruption.” Indeed, the philosophy behind the tool is that no one is better positioned to help plan a community than those who actually live in it and have the social knowledge to understand how people need to move around their neighborhoods. In other words: This thing will be very useful in community meetings.

In its simplest terms, reblocking has been going on as long as there have been slums—“It’s just playing around with space,” says Ziervogel. In the past decade, organizations like his, operating under Shack/Slum Dwellers International, have worked with slum communities around the world on formal reblocking efforts using hand-drawn maps—translated into design software—to gradually improve street plans.

Last year, Flamingo Crescent, an informal settlement outside Cape Town, completed reblocking and installing water, sanitation, and electricity for all of its 104 households. It took nearly three years to get there, and for good reason: Neighbors had to negotiate inherently sensitive changes to their properties, and the community had to work with NGOs and local government align the plan with municipal expectations. Technology will hopefully speed up this process.

“In a lot of formal urban planning, the question is, ‘How do we solve the slums problem?’” says Christa Brelsford, a postdoctoral fellow at the Santa Fe Institute. “The conception is that this is too hard, that the only way is to start over from scratch. People who live in slums don’t agree with that assessment, and don’t want to be resettled.”

The researchers are very clear on what the Open Reblock tool will not do: command community members to raze their houses and rearrange them into straight, neat grids. The source code favors pathways that do not get in the way of existing homes or neighborhoods fixtures, which means they sometimes turn out a bit wiggly. And the physical construction process is meant to be gradual, with community members working with government to upgrade clusters of blocks at a time.

The graphic below depicts a sample re-blocking project in the Epworth neighborhood of Harare, Zimbabwe. The far left shows the area before reblocking, with streets in black and properties without street access highlighted in orange. Properties with access are surrounded by dotted gray lines. In the middle is an image of the same neighborhood in the midst of reblocking, with just four properties left still isolated from road access. On the far right is the neighborhood after reblocking: All parcels now have access to the street.

A sample reblocking project in the Epworth neighborhood of Harare, Zimbabwe. (Open Reblock)

Eventually, researchers say, the tool will be available both on and offline. They expect to finish the prototype within three months. Meanwhile, Brelsford will travel with other research team members to Nairobi, to learn more about slums from a design perspective. Eventually, SDI will select a community in South Africa in which to first use Open Reblock.

While the tool’s potential for streamlining reblocking is great, it’s not a silver bullet. “There’s a specific social process that needs to be part of the solution,” Ziervogel says. “Technical solutions cannot be simply dumped on a community. They need to be involved in shaping and leading the process.” Tools like Open Reblock wouldn’t even exist, he adds, without the foundation work of community-driven organizations like SDI and its many affiliates on the ground.

“One of the things that is defining of SDI’s work is helping communities put themselves on the map,” Lobo says. He describes the power and attention slums can draw—from governments, from government services, from other people who live in the city—by creating a way to point to the places where people work and live. “That simple map is an issue of great contention between slum dwellers and the powers that be. [They say,] ‘We are making ourselves visible.’ They want to and need to tell the authorities where they live.”

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