| Research

COMPLEXITY IN URBAN SYSTEMS

The space and time signatures of cities can give an insight into the complex dynamical processes that led to their development. Beyond just the visual, qualitative analyses, we measure the spatial organization of cities across various time periods and provide a statistical picture of urban development for various city data sets.

Road Network Complexity and Evolution

Road networks have evolved from antiquity, driven by the need to transport people and goods from one place to another. Moreover, the individual roads themselves are the most permanent components in the urban landscape. As such, the historical development and the properties of the city may be gleaned from the records embedded in its road network. The researchers from the group explore the complexity and the evolution of modern and contemporary roads, using data sets from self-organized and planned cities, to reveal the possible global patterns and the underlying local insights about the development of the urban zones.

FEATURED RESEARCH

Understanding the evolution of the road network of Manila, Philippines:
Insights from historical and contemporary data

M.T. Cirunay, M.N. Soriano, and R.C. Batac, Preserved layout features embedded in road network development, Journal of Physics: Complexity 1(1), 015004, https://doi.org/10.1088/2632-072X/ab7f4e (2020).

Modern cities are often seen as ever-changing landscapes of glass and concrete, but beneath the surface of asphalt lies a persistent memory of the past. In a 2020 study published in the Journal of Physics: Complexity, researchers Michelle Cirunay, Maricor Soriano, and Rene Batac explored how road networks evolve over time. By treating cities as living, growing organisms, the team sought to understand whether the original elements of a settlement’s layout remains visible even after decades of urban expansion and densification.

Analysis of the topological periphery of road networks:
Lessons from Metro Manila cities

R.C. Batac and M.T. Cirunay, Shortest paths along urban road network peripheries, Physica A: Statistical Mechanics and its Applications 597, 127255, https://doi.org/10.1016/j.physa.2022.127255 (2022).

M.T. Cirunay and R.C. Batac, Evolution of the periphery of a self-organized road network, Physica A: Statistical Mechanics and its Applications 617, 128629, https://doi.org/10.1016/j.physica.2023.128629 (2023).

In the study of urban planning, the city center often steals the spotlight, but recent research by physicists Michelle T. Cirunay and Rene C. Batac highlights the importance of the edges in urban road network studies. By applying the principles of statistical mechanics to road networks, the duo explored how the topological (network) periphery evolves over time, and looked at how complicated the traversals are from one such peripheral location to another.

Spatio-Temporal Spreading of Urban Structures

The density of man-made structures is the most visual indicator of an urban system when viewed from a satellite map. At first glance, the arrangement of these structures may appear to be random and erratic, especially for the self-organized cities in countries with developing economies. The group classifies these structures and investigates the evolution of their collective development over time. We give a particular focus to the Metro Manila conurbation, the National Capital Region of the Philippines, which has a highly decentralized administration over a relatively small and dense urban area. The tools developed from our analyses may be helpful in understanding other urban zones, especially those under similar geopolitical and economic conditions.

FEATURED RESEARCH

Understanding the evolution of the road network of Manila, Philippines:
Insights from historical and contemporary data

M.T. Cirunay, M.N. Soriano, and R.C. Batac, Preserved layout features embedded in road network development, Journal of Physics: Complexity 1(1), 015004, https://doi.org/10.1088/2632-072X/ab7f4e (2020).

Modern cities are often seen as ever-changing landscapes of glass and concrete, but beneath the surface of asphalt lies a persistent memory of the past. In a 2020 study published in the Journal of Physics: Complexity, researchers Michelle Cirunay, Maricor Soriano, and Rene Batac explored how road networks evolve over time. By treating cities as living, growing organisms, the team sought to understand whether the original elements of a settlement’s layout remains visible even after decades of urban expansion and densification.

Complexity in urban tree cover

E.R. Hernandez, P.B. Sy, M. Cirunay, and R.C. Batac, Power-law distributions of urban tree cover. Physica A: Statistical Mechanics and Its Applications 643, 129779, https://doi.org/10.1016/j.physa.2024.129779 (2024).

Upon looking closely at a satellite image of a modern megacity, one sees a chaotic gridlock of concrete, asphalt, and skyscrapers. Amidst this urban sprawl, patches of greenery, from expansive public parks to lone clusters of trees in abandoned lots, appear as completely random patches. Some of these tree-covered areas are accidental remnants of the previous environmental state of the place, which are now unrecognizable from the breakneck pace of development. On the other hand, majority of the city’s remaining tree cover is shaped strictly by human whims and chaotic planning, leaving behind an unpredictable mosaic. By viewing these patches as unintended results of urbanization, it is safe to assume that the patterns they leave behind are erratic and random. However, a recent study by physicists from De La Salle University reveals that underneath the artificial chaos of the concrete jungle, the underlying forces of urbanization quietly obey an invisible, universal mathematical principle.

Universal Statistical Signatures of Urban Development

The distributions of many urban entities, including, among others, city populations and geographical areas, wealth and income, and even the extent of infrastructure and development, follow highly-skewed distributions, scaling behavior, and other statistical regularities. The complex origins of these emergent statistical manifestations is of interest to complex systems scientists, econophysicists, and other researchers due to their uniquity and regularity across various space and time scales. We aim to describe and model the occurrence of these universal laws in the Philippine data sets, using historical data for a comprehensive analysis.

FEATURED RESEARCH

Zipf's laws and Pareto distributions in Philippine cities and municipalities

D.M.T. Ordoñez and R.C. Batac, Testing the validity of Zipf and Pareto laws: A multi-method approach, Physica A: Statistical Mechanics and Its Applications 675, 130827, https://doi.org/10.1016/j.physa.2025.130827 (2025).

A 2025 research published in Physica A: Statistical Mechanics and its Applications has uncovered a striking mathematical regularity in how population is distributed across the Philippines. By analyzing two decades of census data (2000–2020), researchers Dylan Marcus T. Ordoñez and Rene C. Batac from De La Salle University applied the principles of complexity science to determine if Philippine cities follow the famous Zipf and Pareto laws.

Complexity in urban tree cover

E.R. Hernandez, P.B. Sy, M. Cirunay, and R.C. Batac, Power-law distributions of urban tree cover. Physica A: Statistical Mechanics and Its Applications 643, 129779, https://doi.org/10.1016/j.physa.2024.129779 (2024).

Upon looking closely at a satellite image of a modern megacity, one sees a chaotic gridlock of concrete, asphalt, and skyscrapers. Amidst this urban sprawl, patches of greenery, from expansive public parks to lone clusters of trees in abandoned lots, appear as completely random patches. Some of these tree-covered areas are accidental remnants of the previous environmental state of the place, which are now unrecognizable from the breakneck pace of development. On the other hand, majority of the city’s remaining tree cover is shaped strictly by human whims and chaotic planning, leaving behind an unpredictable mosaic. By viewing these patches as unintended results of urbanization, it is safe to assume that the patterns they leave behind are erratic and random. However, a recent study by physicists from De La Salle University reveals that underneath the artificial chaos of the concrete jungle, the underlying forces of urbanization quietly obey an invisible, universal mathematical principle.