2D City Growth: A Cellular Automaton Model of Urban Expansion

What 2D City Growth Is

The 2D City Growth simulation is an advanced cellular automaton (CA) model that simulates urban development on a flat, two-dimensional plane. Unlike traditional CA models that rely solely on neighbor counts to determine cell states, this model incorporates the influence of actual road networks and accessibility fields.

Each cell in the grid represents a potential plot of land, and its state can transition between unoccupied (empty) and occupied (developed). The development probability for each empty cell is determined by an accessibility field that combines the distance to the nearest road and existing development.

Why It Happens

The simulation leverages principles from urban geography, specifically the concept of accessibility. Accessibility refers to how easily a location can be reached by transportation networks. In this model, cells closer to roads and existing development have higher probabilities of becoming developed.

By adjusting the 'Road attraction' slider, users can observe how the balance between ribbon-like sprawl along corridors and compact, contiguous growth around the core changes. This demonstrates the significant impact that road infrastructure has on urban form.

Real-World Applications

The 2D City Growth model can be applied to understand and predict patterns of urban sprawl and development, which is crucial for city planners and policymakers. By simulating different scenarios, researchers can evaluate the effects of road networks on urban expansion and identify strategies to promote more sustainable growth.

Additionally, this model can help in understanding historical patterns of city growth and how they have been influenced by transportation infrastructure over time.

Key Controls

The simulation features several key controls: 'Growth rate' adjusts the speed at which cells transition from empty to developed, allowing users to observe development patterns in real-time or fast-forward through years of growth.

'Road attraction' modulates the influence of roads on development probability, showing how different road networks can lead to distinct urban forms. The 'Densify' slider controls the density of development, affecting how compactly cells are occupied.

Frequently asked questions

Try it live

Everything above runs in your browser — open 2D City Growth — Road-Weighted Urban CA and change the parameters while it is running. Nothing is installed, nothing is uploaded, the whole model lives in one tab.