Shannon Batch – Director at PSA Consulting
Many towns and cities across Australia are experiencing ‘growing pains’ as communities adjust to increasing population – and the challenges and opportunities it brings. Growth is a hot button topic, demanding evidence-based decisions to address the complexities of limited supply and developed areas.
Consequently, there’s a need for decision support systems, such as urban growth models, especially in rapidly growing areas.
Urban models integrate various data such as economics, geography, sociology, and statistics to understand the effects of urban change. They simplify urban functions to demonstrate, classify, and explain them, aiding in predicting how actions will impact the built environment.
Urban models are computer-based simulations used for testing theories about spatial location and interaction between land uses and related activities. They also provide digital environments for testing the consequences of physical planning policies on the future form of cities.
Michael Batty – University College, London
Why urban modeling matters?
Increasingly used in local government planning, urban growth models guide strategic planning efforts. By using these models, governments gain access to the latest information crucial for making informed decisions on development, land use, and infrastructure planning. They are powerful, evidence-based, dynamic and integrated, playing a pivotal role in shaping urban systems and built environments.
They allow for:
Testing and comparing scenarios.
Integrating with large datasets, such as infrastructure network information and development assessment and building data.
Monitoring the implementation of land use policies.
Aiding in strategic planning by allocating and measuring growth while considering constraints and land use parameters.
These models draw on numeric and spatial inputs, offer dynamic testing capabilities, and are integrated with GIS interfaces and infrastructure planning data.
Urban modelling is particularly powerful for larger LGA’s experiencing rapid growth. However, modelling can be undertaken for any spatial extent. Modelling offers the following benefits:
A base on which to continue to build and manage ongoing growth.
Ability to keep adding additional data to keep evolving the model.
Allows ongoing predictive modelling as areas shift and change.
Improves understanding and insight.
Provides confidence in decision-making.
Manages multiple scenarios streamlining assessment and reducing errors.
Provides evidence to support stakeholder engagement.
Challenges in using urban models
When using urban modelling in land use planning, several factors should be considered.
Models are only as impactful and powerful as the inputs used to build them. It is critical that data used to build and run models are sourced from credible and highly regarded sources and assumptions are thoroughly prosecuted and agreed with an awareness of the limitations of any data sets or limitations.
These models are inherently technical, requiring proficiency in organising raw data and numerical analysis. Collaborating with a skilled consultant, such as PSA, ensures the accurate setup of models from the outset. Subsequently, training can be provided to empower the team to effectively manage and enhance these models over time.
Models are ‘number heavy’ and the raw outputs can be overwhelming and difficult to navigate. Finding ways to communicate modelling outputs and findings clearly and concisely is challenging. It can take significant time to prepare material that is digestible and informative for a range of audiences, but it is critical to get people engaging with modelling outputs as an evidence base.
Real-world application: Case study
Population and dwelling allocation in a growing local government area
Amid rapid growth, a local government area (LGA) encountered significant challenges regarding housing availability and the availability of land for new developments. As the LGA aimed to foster sustainable growth, concerns arose about maintaining appropriate density, addressing infrastructure strains, and preserving the area’s unique character. It became critical to understand the LGA’s ability to accommodate this growth, especially considering capacity shortages and environmental constraints, including natural hazards.
In response, the council embarked on a comprehensive analysis, considering different land use and density assumptions alongside community feedback. The situation revealed a scenario where the LGA faced low rental vacancies and increased residential land uptake but still struggled to meet demand. This prompted the council to make urgent important decisions with long-term implications.
With pressures from both the development industry and concerned citizens, the council sought to strike a balance. They began by:
- Establishing key assumptions,
- Confirming future population estimates,
- Analysing the spatial extent of growth beyond the existing urban boundary,
- Testing the impact of different densities and housing types,
- Exploring the financial implications for servicing growth, and
- Front-loading constraints, such as an assumed yield reduction in high bushfire risk areas and green space corridors
Using this approach, the council ran the urban models to allocate growth across different statistical areas (SA2s), enabling them to identify areas with sufficient capacity for growth and those facing shortfalls. This process triggered testing of various zoning scenarios and expansion into rural lands, leading to the reallocation of growth until a preferred scenario emerged.
Key outcomes
This case study highlights the effectiveness of front-loading constraints and demonstrates the ability to test different zoning, infrastructure plans and density assumptions based on community and stakeholder input. It underscores the importance of proactive planning in managing growth pressures while balancing diverse stakeholder interests. The outputs from the model informed a growth plan for the region, providing a framework for sustainable growth planning.