Scientists are now seeking to study the complexity of urban systems just as they are looking at the complexity of atomic structures and galaxies – with the aim of designing the perfect city.
Franz Ulm and Roland Pellenc are two scientists specialising in the atomic structure of cement at the Massachusetts Institute of Technology (MIT). They have discovered some surprising correlations between the density of cities and elements of the periodic table. When charted, Chicago’s grid structure forms a shape identical to argon’s neat crystalline configuration, while Seattle, birthplace of grunge music, whose irregular layout makes it easy for tourists to get lost, looks like the element’s gaseous form, floating freely. “This surprising analogy supports the idea that the laws of particle physics can be applied to the layout of cities,” say the researchers. And they are not alone – other scientists (physicists, town planners, statisticians, architects, psychologists, etc.) are also beginning to take a close look at urban design. This is an ambitious plan: – in order to predict what the city of the future will be like, they are attempting to create the framework for a new “urban physics” that can establish the laws governing urban design.
“Cities have a complex shape that you won’t find anywhere else in nature,” says Luis Bettencourt, a physicist specialising in complex systems at the Santa Fe Institute. “It is not simply a community of individuals but also the connections between them. All other aspects, such as the roads we build to reach people, the density that this requires, economic products and our collective ideas are a corollary of this”. In an article in Science magazine, the researcher looked at not just the structure of cities but also at how they work, claiming that, from Paris to Boston, including Toulouse, all cities obey a set of universal parameters. We have to ask ourselves what cities do instead of what they look like and how they grow,” says Bettencourt. When individuals gather in dense communities, it is obvious that together they create a dynamic capable of achieving creative and economic results”. Bettencourt refers to this as a ‘social reactor’, which consequently evolves in line with a small group of mathematical principles describing how the city’s elements vary according to the size of the population and the interactions between its individuals.
From Paris to Boston, including Toulouse, all cities obey a set of universal parameters. We have to ask ourselves what cities do instead of what they look like and how they grow.
Bettencourt’s work has found practical use among town planners and policy-makers. “If we know how the system works, we can optimise it by creating as many positive social interactions as we can with low energy- and mobility-related costs. In his model, barriers to socialisation such as crime or segregation, along with social catalysts that help people to connect, such as transport and electricity, form part of the equation. A dense yet crowded city, for example, loses some of its potential, which could be regained through more efficient public transport systems.
These equations will be invaluable in the smart construction of the 200 cities equivalent to the size of New York that will be needed to deal with the urban demographic explosion by 2050. This is also the firm belief of Marta Gonzalez, an impassioned physicist at MIT’s research centre for complex networks. In order to gain an objective idea of what makes a successful city, Gonzalez is recreating individual behavioural patterns seen in urban mobility. For fourteen months, using information from the mobile phones of two million people living in the city of Boston, her team plotted their movements, with some surprising results. Each person visited between ten and a maximum of a hundred different places each year, and this is not just the case for Bostonians. “Despite the richness of human history, people follow simple and reproducible models that, in terms of space and time, demonstrate considerable regularity,” according to Marta Gonzalez. Her team has extracted some valuable information for urban planners; Gonzalez draws together all points of human influx and density on a city map and easily identifies the hot-spots than can cause traffic jams. “With variables such as the number of vehicles, road capacity, and journey time between two points, our law determines precisely where investment in infrastructure is needed,” says Marta Gonzalez.
Despite the richness of human history, people follow simple and reproducible models that, in terms of space and time, demonstrate considerable regularity.
The market potential of these mathematical urban planning tools has not escaped the notice of entrepreneurs. In France, François Grosse set up the company ForCity two years ago and already has 50 staff, including IT developers and geo-data analysts. “Our digital models make it possible to design malleable scenarios helping decision-makers to optimise their investments according to the calculations of possible changes to the area,” Grosse explains. One of his research projects is a simulation of the future of Lyon’s Gerland quarter, which sits on the shores of the Rhone. The city authorities wish to make the area into an eco-development, involving a cluster of laboratories, residential programmes and a transport hub. “It’s not just about measuring the energy consumption, or the digital and mobility needs of this new neighbourhood, but also its impact on the overall workings of Lyon’s urban system,” explains François Grosse. “How will public transport needs change? By how much will property prices go up or down? What will be the effects on nightlife? The relevant data will allow us to answer these questions”.
This is an important goal, as it could save millions of euros. “The number of city-dwellers will grow by about 2 million per week by 2030,” says Christophe Reinhart, who runs MIT’s Sustainable Design Lab. Designing a building that complies with all the strictest environmental regulations without considering its integration is not enough. In order to keep the future cities’ greenhouse gas emissions under control, buildings will have to take account of their surroundings. Our work uses models that circulate heat and mass in and around buildings to predict their energy consumption and to provide estimates for an entire neighbourhood according to the buildings’ type and height and the materials they are made from”. Is the future of mankind just a question of maths?
By Paul Molga, Boston