# Christaller’S Central Place Theory

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1. Christaller’s Central Place Theory & Reilly’s Law of Retail Gravitation Valentina Kasperova IB Geography HL Unit: Settlements
2. Key Terms To Understand
• Central Place – A settlement, i.e. hamlet, village or market town
• Range – Maximum distance people are prepared to travel for a good or service
• Threshold – Minimum # of people required for a good or service to stay alive
• Low Order Goods – necessities (bread)
• High Order Goods – luxuries (computer)
• Sphere of Influence – Area served and affected by a settlement
3. Key Assumptions
• Isotropic Island – area with no variation in relief or climate – flat
• Rational Behavior – assumption that people minimize distance they travel to obtain a good or service
• Even Distribution – population and resources
• All consumers have similar purchasing power
• Transportation costs are equal in all directions and proportional to distance
4. Arrangement of Central Places
• Because transport is equally reachable from all distances, market areas are CIRCULAR (Graph C)
• HOWEVER – Circular shape results in un-served or other served market areas (grey areas)
• So, Christaller suggested a HEXAGON shape (Graph D)
• What this suggests :
• - within a given area, there will be fewer high order settlements (towns) in relation to lower order settlements
• - theoretically, settlements are equidistant from each other, higher order settlements further away from each other
5. Key Principle Threshold & Range Applied
• In theory – low order goods have a low range and low threshold – less people needed to support it, smaller the distance people are willing to travel
• Low range and low threshold goods are sold in SMALL TOWNS, VILLAGES etc.
• Higher ranges and higher thresholds are sold in LARGE TOWNS
• Same true for services – small town likely to have only general doctor, city a hospital ect.
6. Intro – Gravitational Models
• Based on Newton’s law of gravity
• As size of one town increases, so does the movement between them
• However, further apart towns are, the less movement ? distance decay
• Models can be used to predict:
• Traffic flows
• Migration between 2 areas
• For our purposes, the concept of breaking points is essential – customer preferences caused by distance
7. Breaking Points Reilly’s Gravitation Model Applied
• Gravitational models say: along a route between Point A and Point B there will be a breaking point
• People on left side of the breaking point would shop in Town A, while people on right side of it would shop in Town B
• Operates on assumption that larger towns attract more people ? logical behavior
• See attachment for applied examples
Explanation of Equation M ab = Distance of breaking point from Town B D ab = Distance between Town A & B P a = Population of Town A P b = Population of Town B
8. Limitations to Gravity Models
• Limitations regarding these two assumptions
• Larger the town, the stronger the attraction
• People purchase in a logical way
• Problem is that assumptions do not always have to be true
• Examples:
• Traffic jam on way to larger town, difficult and expensive parking
• Smaller town might have fewer but higher quality shops
• Smaller center might be more comfortable: cleaner, modern, safer
• Some people might have to depend on public transport ? difficult
• Basis is assumptions are UNREALISTIC – people aren’t predictable
9. A Little Visual… Important Note: The borders basically are the breaking points between the settlements
10. Limitations to CPT
• Large areas of flat land rarely exist (i.e. Netherlands) ? transport is “uneven”
• More types of transport – costs cannot be proportional to distance
• People and wealth are not evenly distributed
• People do not always go to the nearest place
• Purchasing power of people differs
• Perfect competition is unreal – some make more than others
• Shopping habits have changed – People travel larger distances to buy lower order goods (i.e. hypermarkets)
• Theory sees central place as having a particular function ? in reality, places have several which change over time
• The model is
• COMPLETELY UNREALISTIC
• In today’s world
11. So Why Do We Have/Use It ... ?
• Theory has helped geographers and planners to locate new services and plan settlements (i.e. Tesco)
• Valuable information can come from analysis of the model’s results vs. reality ? explaining the difference
• NEVER FIT REALITY INTO THE MODEL, FIT THE MODEL INTO REALITY