Cartographic Skills » Route and Sphere of Influence Maps

What you'll learn this session

Study time: 30 minutes

What route maps and sphere of influence maps are
How to interpret and create route maps
How to identify and map spheres of influence
Practical applications of these cartographic skills
How to analyse patterns using these mapping techniques

Introduction to Route and Sphere of Influence Maps

Maps are powerful tools that help geographers understand spatial relationships. Route maps and sphere of influence maps are two important cartographic techniques that help us visualise movement, connections and the reach of services or settlements.

Key Definitions:

Route Map: A map showing paths of movement between locations, such as transport networks, migration flows, or trade routes.
Sphere of Influence: The geographical area over which a settlement, service, or business exerts its influence and attracts people.
Cartography: The art and science of making maps.

🗺 Route Maps

Route maps show how people, goods, or information move from one place to another. They help us understand connectivity and accessibility between places. Examples include bus routes, shipping lanes and flight paths.

🌐 Sphere of Influence Maps

These maps show the area over which a place or service has influence. They help us understand how far people are willing to travel for certain services and how settlements compete with each other.

Understanding Route Maps

Route maps are essential for visualising movement and connections. They can be simple or complex, depending on what they're showing and their purpose.

Types of Route Maps

Route maps come in various forms, each serving different purposes in geographical analysis:

🚌 Transport Networks

Maps showing roads, railways, bus routes, or cycle paths. These help planners understand connectivity and identify areas with poor access.

🚢 Flow Maps

Maps showing the movement of people, goods, or information between places. The width of lines often represents the volume of flow.

🛫 Journey Maps

Maps showing specific routes taken by individuals or groups, such as migration paths or tourism routes.

Creating and Interpreting Route Maps

When creating or reading route maps, consider these key elements:

Direction: Which way is the movement happening? Is it one-way or two-way?
Volume: How much is moving along each route? This is often shown by line thickness.
Mode: What type of transport or movement is being shown?
Connectivity: How well-connected are different places? Are there areas with few routes?
Barriers: What might prevent movement along certain routes?

Case Study: London Underground Map

The London Underground map is a famous example of a route map that sacrifices geographical accuracy for clarity. Created by Harry Beck in 1933, it shows the tube lines as straight lines with regular angles (usually 45° or 90°). This design makes the complex network easier to understand, even though it doesn't accurately represent the real distances or positions of stations. The map has become so successful that transit systems worldwide have adopted similar designs.

Understanding Sphere of Influence Maps

Sphere of influence maps help us visualise the reach and impact of settlements, services, or businesses across geographical space.

Measuring Spheres of Influence

Geographers use various methods to determine and map spheres of influence:

🛒 Questionnaire Surveys

Asking people where they come from to use a service (like a shopping centre) helps establish how far its influence extends. This data can be plotted on a map to show the catchment area.

📊 Breaking Point Analysis

This uses mathematical models to calculate where the influence of one settlement ends and another begins, based on factors like population size and distance.

Reilly's Law of Retail Gravitation

One important model for understanding spheres of influence is Reilly's Law, which states that people are attracted to larger settlements but discouraged by distance. The formula is:

Breaking point = Distance between A and B ÷ (1 + √(Population of A ÷ Population of B))

This helps determine where the sphere of influence of one settlement ends and another begins.

Case Study: Supermarket Catchment Areas

Supermarket chains carefully analyse spheres of influence when deciding where to open new stores. They collect data on where customers travel from and map these catchment areas. If two stores have overlapping catchment areas, they might be competing with each other. Tesco, for example, uses loyalty card data to understand customer travel patterns and optimise store locations. They've found that most shoppers won't travel more than 15 minutes for regular grocery shopping, but might travel up to 30 minutes for a larger superstore with more services.

Practical Applications in Geography

Both route maps and sphere of influence maps have important real-world applications:

🏠 Urban Planning

Planners use these maps to ensure services are accessible and to plan transport networks that connect communities effectively.

🏢 Business Location

Businesses use sphere of influence analysis to find optimal locations that maximise their customer base while minimising competition.

🏥 Service Provision

Governments use these techniques to ensure services like hospitals and schools are located where they can serve the most people efficiently.

Creating Your Own Maps

For your iGCSE Geography coursework or exams, you might need to create or interpret these types of maps. Here are some tips:

For route maps: Use different colours for different routes or types of transport. Vary line thickness to show volume or importance.
For sphere of influence maps: Use concentric circles or irregular boundaries to show the reach of influence. Consider using choropleth shading to show intensity of influence.
Always include: A title, key/legend, scale, north arrow and source of data.

Analysing Patterns and Relationships

The real value of these mapping techniques comes from the patterns they reveal:

🔍 What to Look For in Route Maps

Areas with high/low connectivity
Dominant flow directions
Bottlenecks or congestion points
Changes in routes over time
Relationship between routes and physical features

🔎 What to Look For in Sphere of Influence Maps

Overlapping areas of influence
Relationship between settlement size and sphere of influence
Areas poorly served by services
How physical features affect spheres of influence
Changes in influence over time

Exam Tip: Interpreting Maps

In your exam, you might be asked to interpret route or sphere of influence maps. Remember to:

Describe the pattern you can see (e.g., "The sphere of influence extends further to the east")
Suggest reasons for the pattern (e.g., "This might be because there's less competition from other services in that direction")
Consider limitations of the map (e.g., "The route map doesn't show the frequency of services")
Link to geographical theories where relevant (e.g., "This supports Reilly's Law as the larger settlement has a wider sphere of influence")

Summary

Route maps and sphere of influence maps are valuable cartographic tools that help geographers understand spatial relationships, movement patterns and the reach of settlements and services. By mastering these techniques, you'll be better equipped to analyse geographical patterns and processes for your iGCSE Geography course.

Remember that these maps don't just show what exists - they help us understand why geographical patterns occur and how they might change in the future. This understanding is at the heart of geographical thinking.

🧠 Test Your Knowledge!