Three main landmarks make up the “urban pulse” of a city

People often talk metaphorically about the heartbeat or the pulse of a city, but according to the authors of the new paper published in the Proceedings of the National Academy of Sciences, cities do indeed have “urban dynamics”—a measure of urban “metabolic activity” that can be measured. And these methods can help inform future policy on urban planning.

The true meaning of urbanization has changed over the centuries. Zhe Zhu of the University of Connecticut and his co-authors took the main text of their study. It has “simultaneous transformation strategies in six sectors, including population, economy, infrastructure, environment, governance and culture,” he wrote. “All results bring results, measurable results of the policy, such as population growth, urban land expansion, GDP growth, and innovation.” Their chosen criteria reflect this strong point of view: Cities are not static places but “environmental spaces.”

“For many years, we had only seen the effects of urbanization—the buildings that have been built, or the expansion of roads,” said Zhu. “But you don’t see how things are going in the cities. This is going to be a very powerful tool that will not only affect the development decisions from the governments but also the grassroots decisions from the people who move around in their cities.” One day we can see how people in our community are doing when we are looking for a house, for example, or we are looking for a place to start a new business.

Thanks to advances in remote sensing and various monitoring techniques, it is possible to collect a variety of data from different sources, such as satellite images, or mobile phone or internet data. Zhu et al. obtained data from NASA Harmonized Landsat and Sentinel-2 to investigate new construction, renovation, infrastructure maintenance, green space expansion, and demolition in six cities: Seattle, Shenzhen, Lagos, Mumbai, Dubai, and Mexico City.

Three very important signs

Their research revealed three unique “signals” that illuminate cities. First, urbanization is “excessive”: There are sharp, long-term spurts, not continuous growth. The best example of this, according to the authors, is Dubai, whose coastal areas have shown the largest windows in the renovation project—especially capital-based projects such as high-rise towers or mixed-use buildings. Shenzhen’s spikes, by contrast, were mixed, “showing the city’s capacity for rapid, government-led mobilization,” he wrote.