Urban Growth Makes Urban Structure a Global Issue
Urban Structure
The spatial pattern of land use, activities, and social groups within a city, including how different zones (such as the CBD, residential areas, and industry) are arranged and connected.
- Urban Cities are growing fast, and their internal structure affects billions of people:
- More than half of humanity (over 4.4 billion people) lives in cities.
- By 2030, almost 60% of the world's population is expected to live in urban areas.
- Much of the future expansion is expected in low-income countries (LICs) and middle-income countries (MICs).
- Cities occupy only a small share of land area (around 3%) but account for a very large share of energy use (60-80%) and carbon emissions (about 75%).
- This helps explain why cities develop inner-city deprivation, suburbs, business districts, and in some places slums and informal settlements,
- Urban structure is central to all of these because it shapes who can access jobs, schools, healthcare, clean water, and safe housing.
- Whether a "sustainable city" is possible depends partly on how we define "sustainable."
- If sustainability means "zero impact," then it may be unrealistic.
- If it means "meeting people's needs while reducing harm and increasing fairness," then cities can become more sustainable.
- Definitions influence conclusions.
How Are Cities Understood as Systems With Inputs, Processes, and Outputs?
Urban System
A city viewed as a set of interconnected parts (people, infrastructure, economy, services, environment) that interact through flows of resources, energy, goods, and information.
- A helpful way to understand urban structure is to view a city as an urban system.
- A system has inputs, processes, outputs, and feedback (changes that influence future decisions).
Inputs: What a City Needs to Function
- Common inputs include:
- People (migration, commuting)
- Energy (electricity, fuel)
- Water
- Food
- Raw materials and goods
- Information and technology
- Capital (investment, taxes)
Processes: What Happens Inside the City
- Inside the system, urban structure strongly influences key processes, such as:
- Housing (where different income groups live)
- Transport (roads, public transport networks, walkability)
- Industry and services (where jobs are located)
- Governance and planning (zoning, regulations, public spending)
- Waste management (collection, recycling, sewage systems)
Outputs: What a City Produces and Disposes of
- Cities generate:
- Goods and services (economic output)
- Waste (solid waste, landfill)
- Wastewater and sewage
- Air pollution and greenhouse gases ($\text{CO}_2$)
- Heat (the urban heat island effect)
- Thinking in systems helps you connect urban structure to sustainability.
- For example, if housing is far from jobs (a structural pattern), transport demand rises (a process), leading to higher emissions (an output).
Linear and Circular City Thinking Links Urban Structure to Sustainability
- Richard Rogers (1997) described two broad system types:
- The linear city
- Resources flow in, are used once, then leave as waste and pollution.
- This pattern is typically unsustainable because it depends on continuous high inputs and produces high outputs.
- The circular city
- Outputs are reprocessed (reuse, repair, recycling, renewable energy, water treatment)
- Reduces environmental impact.
- The linear city
- Urban structure shapes how resources move through a city:
- Compact cities support circular flows through shared heating systems, short travel distances, and efficient recycling.
- Dense public transport networks reduce car use and energy waste.
- Car-dependent sprawl increases fuel use and traffic emissions.
- Distant landfill sites reinforce linear “use–dump” systems rather than reuse and recovery.
What Are Some Common Urban Structure Zones?
- Although every city is unique, many have recognizable zones:
- CBD (Central Business District): high land values, offices, major retail, transport hubs
- Inner city (often older housing and former industrial areas): may face decline or regeneration
- Suburbs: mainly residential, often lower density, sometimes wealthier
- Industrial zones: factories, warehouses, logistics, often near transport routes
- Rural-urban fringe: edge of the city where new development and land-use conflict are common
CBD (Central Business District)
The commercial and administrative core of a city where high-value services and retail often concentrate.
- Do not assume "inner city" always means "poor" or "dangerous."
- Inner-city areas can experience deprivation, but they can also be regenerated through investment, rising property values, and new services.
How Do Urban Structure Models Explain Patterns (and Their Limits)?
- Geographers use simplified models to explain typical patterns of land use.
- These models are not perfect maps of reality, but they help you identify trends and compare cities.
Concentric Zone Model: Growth in Rings
- This model (Burgess) suggests cities grow outward in rings:
- CBD at the centre
- A zone of transition (often older housing and mixed land use)
- Working-class residential zones
- Middle-class zones
- Commuter/suburban zone
The key idea is land value and accessibility shape where activities locate.
Sector Model: Wedges Along Transport Routes
- This model (Hoyt) suggests land use forms sectors (wedges) from the CBD outward:
- Industry and lower-income housing often extend along railways, rivers, or major roads
- Higher-income residential sectors develop in more attractive locations (for example, upwind, higher ground, near amenities)
The key idea is transport corridors guide growth.
Multiple Nuclei Model: Several Centres of Activity
- This model (Harris and Ullman) argues that modern cities often develop multiple nodes:
- A CBD may still exist, but other nuclei appear (universities, airports, suburban shopping centres, industrial parks)
The key idea is specialization and decentralization create several "mini-centres."
- Models were often developed using cities in higher-income countries.
- Applying them to rapidly growing cities in lower-income countries may require changes, especially where informal settlements are widespread.
What Kind of Spatial Patterns Does Inequality Have?
Urban structure frequently reflects (and reinforces) inequality.
Inner-City Deprivation in Many High-Income Countries
- In many HICs (high-income countries), the inner city often shows high levels of inequality and deprivation linked to:
- Older housing stock
- Deindustrialization (decline of manufacturing jobs)
- Reported inner-city problems can include:
- Overcrowded housing
- Higher death rates and infant mortality
- Social segregation
- Persistent unemployment
- These issues can interact in a cycle of deprivation, where disadvantage in one area (for example unemployment) increases vulnerability in others (health, housing, education), making it hard for communities to escape.
Cycle of Deprivation
A self-reinforcing pattern where social and economic problems (such as unemployment, poor housing, and ill health) interact and make long-term disadvantage more likely.
Informal Settlements in Many Lower-Income Countries
- In many LICs and MICs (low- and middle-income countries), rapid rural-urban migration can lead to:
- Slums
- Shanty towns
- Squatter settlements
- These often involve overcrowding and inadequate access to safe water, sanitation, and secure housing.
- As cities expand, land becomes scarce and disputes about land use become more common.
- A common misconception is that informal settlements exist because residents "choose" them.
- In reality, they are often the result of fast urban growth, limited affordable housing, and unequal access to land and services.
How Do Urban Planners Design For Sustainable Urban Structures?
- Here, two broad approaches are commonly discussed:
- Purpose-built sustainable cities (eco-cities): planning from the start with sustainability technologies and design.
- Retrofitting existing cities: upgrading infrastructure, transport, housing, and public space in places where millions already live.
- Both approaches aim to improve sustainability across environmental, social, and economic dimensions.
Retrofitting
Improving existing buildings, infrastructure, and systems (such as transport and energy) to increase efficiency, reduce environmental impact, and improve quality of life.
Masdar City
- Masdar City is a useful example of a purposely built city that does not neatly fit classic urban models.
- How did it perform in practice?
- Strengths
- Street layout, shading, and building orientation reduced cooling demand.
- Pedestrian-first design limited car dependence by structure, not choice.
- Energy use patterns were shaped by layout from the start.
- Limitations
- High costs and slow population growth limited its impact.
- The model is difficult to apply to existing cities built under older urban patterns.
- Most cities cannot be rebuilt from scratch.
- Strengths
- When referring to purpose built cities like Masdar, mention:
- “This works best in newly planned cities and is harder to apply to older cities shaped by concentric or sector growth.”
- This demonstrates understanding that structure matters, but also shows the limits of theory when applied to the real world.
How Does Urban Structure Connect Directly to Transport, Public Space, and Inclusion?
- UN-Habitat argues that making cities safe and sustainable involves:
- Access to safe, affordable housing
- Upgrading slum settlements
- Investment in public transport
- Creating green public spaces
- Improving urban planning and management in ways that are participatory and inclusive
- Notice how these are all structural issues:
- If housing is pushed to the edge without transport, inequality grows.
- If the city prioritizes cars, land use spreads out and emissions rise.
- If green space is unevenly distributed, health outcomes and quality of life become unequal.
- Always structure your answer using the three pillars: social, economic, and environmental sustainability.
- For each pillar, link a feature of urban structure (for example compactness, segregation, land-use zoning) to at least one impact and one management strategy.
Urban structure strongly influences sustainability because it shapes daily behaviour rather than relying on individual choice. In terms of social sustainability, compact and mixed-use neighbourhoods improve access to jobs, schools, and healthcare, which can reduce social exclusion and improve quality of life. However, if density is poorly managed, it can also increase overcrowding. This is why planning policies that combine high-density housing with adequate services and public transport are essential.
From an economic sustainability perspective, land-use zoning that concentrates businesses near transport hubs increases productivity by reducing travel times and transport costs. This supports economic growth and employment, especially in large cities. However, excessive concentration can raise land prices and exclude smaller firms. Governments can manage this through transit-oriented development that spreads economic activity across multiple well-connected centres.
In terms of environmental sustainability, compact urban design reduces urban sprawl and car dependence, lowering fuel use, air pollution, and carbon emissions. These benefits are strongest when public transport and cycling infrastructure are prioritised. Without these investments, density alone may not reduce emissions. This shows that urban structure must be supported by effective transport planning to achieve environmental goals.
Overall, urban structure can support sustainability across social, economic, and environmental dimensions, but only when density, zoning, and transport are carefully managed together.
- Define "Urban Structure" in the context of city planning.
- According to the Sector Model (Hoyt), what primary factor guides the formation of land-use wedges extending from the CBD?
- What is the fundamental difference between a "Linear City" system and a "Circular City" system regarding resource use?
- Explain the concept of the "Cycle of Deprivation" found in many inner-city areas.
