Horizontal versus vertical urban structures and urban land-use zones

Urban Structure and Change (Cambridge IGCSE/A‑Level Geography 9696)

Learning Objective

Compare horizontal and vertical urban structures, explain the drivers that shape them, analyse how urban activities relocate over time, describe residential zonation, and evaluate strategies for sustainable urban development.

1. Urban Growth – Types, Causes, Consequences & Hierarchy

• Urbanisation – migration from rural to urban areas and natural increase in cities; expands the size of the urban population.
• Suburbanisation – movement of households and jobs from the CBD to the outer suburbs, creating low‑density residential belts.
• Urban sprawl – uncontrolled, low‑density expansion beyond the built‑up edge, often linked to car dependence.
• Counter‑urbanisation (de‑urbanisation) – people and some services move from cities to smaller towns or rural areas.
• Re‑urbanisation (inner‑city renewal) – regeneration of inner‑city land for housing, offices or leisure (e.g., London Docklands).

Causes

• Demographic pressure (population growth, household formation).
• Economic change (shift from manufacturing to services, globalisation).
• Policy & planning (housing quotas, green‑belt legislation, infrastructure investment).
• Technological advances (improved transport, ICT enabling remote work).

Consequences

• Environmental: loss of agricultural land, increased carbon emissions, heat‑island effect.
• Social: segregation, pressure on housing affordability, changes in community cohesion.
• Economic: altered land‑price gradients, new employment centres, changes in commuting patterns.

Urban Hierarchy

• Town → City → Metropolis → World City – each level provides a wider range of services and a larger catchment area.
• Primate city – a single city dominates a country’s population, economy and political power (e.g., Bangkok, Thailand).
• World city – a global hub for finance, trade, culture and politics (e.g., London, New York, Tokyo).

2. Horizontal Urban Structure

Horizontal structure describes the spatial distribution of land‑uses on the ground plane.

Classic Models

• Concentric Zone Model (Burgess, 1925)
  1. Central Business District (CBD)
  2. Transition zone (mixed‑use, declining housing)
  3. Working‑class residential
  4. Better‑off residential
  5. Commuter belt (sub‑urban)
• Sector Model (Hoyt, 1939) – development follows major transport corridors, producing wedges of similar land‑use (e.g., industrial along rail lines, high‑status housing along highways).
• Multiple‑Nuclei Model (Harris & Ullman, 1945) – a city contains several independent centres (ports, university campuses, shopping districts) that attract specialised activities.

Real‑World Examples

• Concentric pattern: Paris – clear CBD, inner residential rings, outer commuter belt.
• Sector pattern: Chicago – industrial sectors along the lakefront and rail lines.
• Multiple nuclei: Los Angeles – distinct sub‑centres such as Hollywood, the San Fernando Valley, and the Port of LA.

3. Vertical Urban Structure

Vertical structure uses building height to accommodate functions where land is scarce or expensive.

Key Forms

• High‑rise residential towers – maximise dwelling units on a small footprint (e.g., Hong Kong’s public housing estates).
• Mixed‑use skyscrapers – combine retail (ground floor), offices (mid‑floors) and apartments (upper floors) in one tower (e.g., Shanghai World Financial Center).
• Vertical zoning – deliberate allocation of different uses to specific floors, such as hotels above office blocks or schools on lower levels of a tower.

Why Cities Go Vertical

• High land‑price gradients near the CBD.
• Limited buildable land due to physical constraints (coastlines, hills, protected areas).
• Policy incentives (floor‑area ratios, density bonuses) that reward vertical growth.

4. Factors Influencing Urban Structure

Factor	How it Shapes Structure
Physical (topography, climate, water)	Rivers, hills and flood‑plains channel the location of the CBD, transport routes and high‑density zones.
Economic (land‑price gradient, employment patterns)	High values near the centre encourage vertical, high‑value development; cheaper fringe land favours horizontal expansion.
Social (population growth, household size, cultural preferences)	Rapid growth and small‑household trends drive high‑rise housing; cultural norms may favour detached homes.
Political/Planning (zoning, green‑belt policy, housing quotas)	Controls where residential, commercial or industrial uses can be located; green belts limit outward sprawl, height limits steer vertical vs. horizontal growth.
Historical (settlement pattern, legacy infrastructure)	Historic cores dictate the location of the CBD and major transport corridors; older rail lines often become industrial corridors.

5. Changing Location of Urban Activities

• CBD shift / Edge‑city formation – commercial functions move to new sub‑centres when land becomes too expensive or new transport links (e.g., M25 in London) improve accessibility.
• Retail relocation – from high‑street shops to out‑of‑town shopping parks, retail parks and online platforms.
• De‑industrialisation – factories relocate to the urban fringe, overseas low‑cost locations, or are replaced by service‑oriented uses.
• Gentrification – middle‑class households move into former working‑class inner‑city areas, prompting redevelopment and a shift in land‑use.
• Re‑urbanisation of waterfronts – former docks or industrial riverfronts are regenerated for housing, leisure and mixed‑use (e.g., London Docklands, Baltimore Inner Harbor).

6. Comparing Horizontal and Vertical Structures

Aspect	Horizontal Structure	Vertical Structure
Primary focus	Distribution of land‑uses across the ground plane	Use of building height and floor space
Typical drivers	Transport corridors, historic growth patterns, land‑price gradient	Land scarcity, high population density, policy incentives for high‑rise development
Key examples	Concentric zones, sector wedges, multiple nuclei	CBD skyscraper clusters, high‑rise residential estates, vertical mixed‑use complexes
Advantages	Clear functional segregation, easier navigation, lower per‑floor construction cost	Efficient land use, reduced urban sprawl, integration of services within one building
Disadvantages	Urban sprawl, longer commuting distances, higher infrastructure provision costs	Higher construction & maintenance costs, reliance on elevators, potential social segregation

7. Urban Land‑Use Zones

1. Central Business District (CBD) – high‑rise offices, financial services, flagship retail, major transport interchange.
2. Commercial Zone – shops, restaurants, entertainment; often found in secondary centres or along major roads.
3. Industrial Zone – factories, warehouses, logistics parks; usually on the urban fringe or in designated industrial estates.
4. Residential Zone
   • Inner‑city apartments – high density, often vertical.
   • Sub‑urban housing – lower density, predominantly detached or semi‑detached homes.
5. Green Belt / Open Space – parks, recreation areas, agricultural land that limit outward expansion and provide ecosystem services.

8. Zonation of Residential Areas

Residential land‑use is differentiated by socioeconomic status, ethnicity and planning controls.

Socio‑economic Gradient

• In many European cities wealth increases with distance from the CBD (e.g., Paris, Berlin).
• In rapidly expanding Asian megacities the opposite pattern can appear, with high‑value high‑rise apartments in the inner city and low‑cost peripheral housing (e.g., Shanghai).

Housing Typologies

• High‑rise estates – public or private towers (Hong Kong, Singapore).
• Low‑rise suburban estates – detached, semi‑detached or townhouses (Los Angeles, Manchester suburbs).

Planning Controls

• Affordable‑housing quotas – require a proportion of new dwellings to be low‑cost.
• Height limits – restrict vertical growth in historic cores (e.g., Edinburgh).
• Design codes – dictate building form, setbacks and open‑space ratios.

Case‑Study Contrast

• Hong Kong – extreme land scarcity, 70 % of the population lives in high‑rise public and private towers; vertical zoning is the norm.
• Los Angeles – abundant land, predominance of low‑rise detached housing, extensive horizontal sprawl, reliance on car‑based transport.

9. Sustainable Urban Development

Key Challenges

• Waste‑management and recycling in dense environments.
• Transport emissions, congestion and air quality.
• Loss of green space, urban heat‑island effect and climate‑resilience.
• Water supply and runoff management in high‑density areas.

Management Strategies (with evaluation prompts)

• Integrated public‑transport networks – tram, bus rapid transit and metro reduce car use.
  Evaluation: high capital cost; must be affordable and accessible for low‑income groups.
• Mixed‑use, high‑density development – combines housing, work and leisure within walkable distances.
  Evaluation: can improve livability but may raise property prices and displace vulnerable households.
• Green infrastructure – green roofs, vertical gardens, pocket parks, sustainable drainage systems (SuDS).
  Evaluation: provides ecosystem services and mitigates heat islands, yet requires ongoing maintenance and community stewardship.
• Waste‑to‑energy and circular‑economy schemes – incineration with energy recovery, extensive recycling programmes.
  Evaluation: reduces landfill pressure but may face public opposition over emissions.

Detailed Example – Singapore’s Sustainable Urban Model

• Vertical green spaces – Gardens by the Bay, extensive rooftop and sky‑garden programmes.
• Integrated transport – MRT network covering >200 km, seamless bus‑rail integration.
• Housing policy – 80 % of residents live in public high‑rise flats built by the Housing & Development Board (HDB) with built‑in communal facilities.
• Evaluation – high quality of life and low car ownership, but land scarcity keeps housing prices high and creates dependence on continual land reclamation.

10. Population Density

The basic relationship between population and area is:

D = P ÷ A

where D = density (people km⁻²), P = total population, and A = land area. High D values typically trigger vertical development and the need for high‑capacity services.

11. Key Concepts for Revision (Cambridge Syllabus)

• Scale – local, metropolitan, regional, global.
• Change over time – how structures evolve with economic, social and policy shifts.
• Place – distinctive characteristics of zones such as CBD, suburb, edge‑city.
• Spatial variation – why similar functions appear in different locations.
• Cause‑and‑effect – linking drivers (e.g., land price) to outcomes (e.g., high‑rise housing).
• Systems – interaction between land‑use, transport, housing and environment.
• Environmental interaction – impacts of urban form on resources, climate and biodiversity.

12. Suggested Diagram

Cross‑sectional illustration* showing a horizontal city layout on the left (concentric zones spreading outward) and a vertical high‑rise district on the right (stacked mixed‑use tower). Colour‑code the main land‑use zones, annotate density gradients and label key functions (CBD, residential, industrial, green space).

13. Quick Revision Checklist

• Horizontal = spread; vertical = stack.
• Identify the five main drivers of urban structure.
• Recall at least three processes that relocate urban activities (e.g., CBD shift, de‑industrialisation, gentrification).
• Describe residential zonation – socioeconomic gradient, housing typologies, planning controls – and give two contrasting case studies.
• State three sustainability challenges and match each with a management strategy; add one point of evaluation for each.
• Be able to sketch and label a simple diagram that contrasts horizontal and vertical structures.