Marc Barthelemy,The structure and dynamics of cities: Urban data analysis and theoretical modeling

Abstract

Reviewed by: Sybil Derrible, Complex and Sustainable Urban Networks (CSUN) Laboratory, University of Illinois at Chicago, United States

DOI: 10.1177/2399808317721785

Since the early 2000s, the science of cities has emerged as an independent discipline that aspires to capture important phenomena occurring in cities. Few scholars have been as active in the field as Marc Barthelemy. It was therefore about time Barthelemy wrote a book on the subject. In The Structure and Dynamics of Cities: Urban Data Analysis and Theoretical Modeling, Barthelemy brings us on an amazing mathematical journey centered on the various models and empirical findings that constitute the roots of the science of cities. The book is indubitably mathematical—after all, Barthelemy is a physicist—but the mathematics are not overbearing. In fact, we must appreciate the level of effort that Barthelemy puts into explaining the main concepts that drive the concepts and models discussed, but the target audience definitely needs to possess strong technical skills. The first chapter of the book may be an exception since it focuses purely on explaining some of the global trends in cities, notably analyzing the differences in the distribution of city size across continents. This first chapter is in fact a formidable introduction to the science of cities, and it is highly recommended to anyone who seeks a general overview of the field. Novice readers to the science of cities will therefore not be lost since Barthelemy starts from the very basics, but he rapidly brings us to some of the latest findings and techniques adopted by the new science such as multi-layer networks from network science that offer a powerful toolkit to study cities.

As the main purpose of the book is to discuss overarching mechanisms that govern the formation and growth of cities, a significant portion of the book is devoted to the discovery of universal patterns (i.e. patterns that exist in all cities) that are often products of complex (bottom-up) processes. In particular, the entire field is endowed to the findings of George Kingsley Zipf who in the 1930s and 1940s found a power law relationship between the magnitude of many urban properties and their rank; this phenomenon is commonly called Zipf’s law. The presence of power laws is recurrent throughout the book, in part with the discovery of scaling laws that govern how certain urban properties evolve as cities increase in population.

Barthelemy himself is perhaps best known for his work on spatial networks (such as infrastructure networks), and an entire chapter is dedicated to spatial networks. Here again, Barthelemy starts out by introducing simple terms, then steadily building on them. The chapter focuses on transportation systems, and the favored technique is network science.

Many of the models throughout the book take their roots in urban economics. In fact, a significant portion of the book possesses an urban economics flavor. Sensibly, cities grow from the interplay between multiple tradeoffs. In particular, the Fujita–Ogawa model is discussed at length in the book, and it takes its premise in the tradeoff of paying a higher rent versus spending more time in transportation. From these basic urban economics principles, Barthelemy explains how cities can grow to be mono-centric or poly-centric. In fact, the issue of modeling mono-centricity and poly-centricity of cities is a common thread in many chapters, and the passion of the author for the topic is clearly palpable in the writing.

One particular section diverges from the main theme of the book, but it is particularly interesting. Two-thirds into the book, Barthelemy reveals that human beings are able to process eight bits of information when traveling in a transportation network, which corresponds to using three public transportation routes and making two transfers. This information is interesting because it offers pragmatic information that can be used by transportation planners about the limit to multi-modality and system complexity.

Overall, the book is best described by Barthelemy himself, who wrote in the concluding thoughts:

The goal of a science of cities would be to understand how cities grow and eventually to provide scientific support for urban planning operations. This book advocates the use of simple models, guided by ideas of the statistical physics of complex systems such as self-organization and minimal models, and subject to the crucial constraint to be in agreement with empirical observations. (p. 247)

The first point made by the author is particularly pertinent. Indeed, as is common in works on the science of cities, a link is missing between the theoretical knowledge gained and the practice (with the potential exception of the eight bits of information study). Despite the increasing interest on the emerging field—a Google search for “Science of Cities” or “Urban Science” retrieves about 900,000 pages—a science is not fully formed until some of the findings are used in practice. The science of cities is still young and has a long way to go, and I have no doubt that Barthelemy will continue to be to one of the major contributors of the field. For now, The Structure and Dynamics of Cities: Urban Data Analysis and Theoretical Modeling offers a great technical introduction to the science of cities, and I have no doubt it will leave its permanent mark in the field.