Rafael Prieto-Curiel (Personal webpage )

Complexity Science Hub Vienna, Austria
Most parts of Africa's infrastructure are yet to be built. Where and how these new buildings are constructed matters since today's decisions will last for decades. Satellite imagery enables the construction of urban form indicators to compare African cities' elongation, sprawl and emptiness. We characterise urban morphology based on the distribution and size of millions of buildings in African cities. Many cities are elongated or sprawled, especially urban areas dominated by small buildings or close to physical barriers or international borders. However, as the population increases, distances grow and become critical, so cities experience intense competition for space and better use it. Larger cities tend to settle more efficiently. For each city, we measure the mean inter-building distance, a proxy for energy consumption related to urban mobility. Distances inside a city grow faster than the square root of its population, resulting from the combined impact of a sublinear growth in the number of buildings and a sublinear increase in building size and urban form indicators. We show that when a city doubles its population, it roughly triples the energy demand related to commutes.