The document discusses Geoffrey West's theory of how cities scale based on their population size. It covers how certain infrastructure elements like gas stations scale sublinearly with population, while socioeconomic indicators like wages and GDP scale superlinearly. Cities exhibit properties of both biological and inorganic networks, with infrastructure resembling space-filling networks and social interactions resembling optimized networks. While Central Place Theory models cities as evenly spaced hexagons, real cities are better described as complex adaptive fractal systems, with road networks resembling circulatory systems in their hierarchical branching structure. Data from smart cities is needed to fully analyze urban scaling patterns.

1. MARGIE'STRAVEL
1
M
SCALEChapter 7 :
TOWARD A SCIENCE OF CITIES
“ EVERYTHING AROUND US IS SCALE DEPENDENT . IT’S WOVEN INTO
THE FABRIC OF THE UNIVERSE “ . Geoffrey West
SCALE-CHAPTER7
MASTER PROGRAM , 도시공하과 학기 1
SOUMAYA EZAZAA - G201936024

2. MARGIE'STRAVEL
2
M
SCALE-CHAPTER7
West tries to explain the growth trajectory
of cities and evaluate the common
features and processes which justify the
translation of the scaling theory in the
biological systems to urban systems.
1. THE SCALING OF CITIES
2. CITIES AND SOCIAL NETWORK
3. WHAT ARE THESE NETWORKS ?
4. CITIES CHRISTALLS OR
FRACTALS ?
FOCUS
CONTENTS

3. MARGIE'STRAVEL
3
M
1. THE SCALING
OF CITIES :
SCALE-CHAPTER7

4. MARGIE'STRAVEL
4
M
SCALE-CHAPTER7
SUBLINEAR AND SUPERLINEAR SCALE :
Humans are example of a sublinearly scaling system.
We grow very quickly at the start, at birth, and over time
our growth slows, and we are all ensured mortality.
HOW ABOUT CITIES ?
TO UNDERSTAND THE GROWTH TRAJECTORY OF CITIES WE NEED TO
UNDERSTAND WHICH SCALING SYSTEM CITIES FOLLOW .
CITIES
COMPLEX SYSTEMS
LINEAR SCALE NONLINEAR SCALE
SIMPLE SYSTEMS
SUBLINEAR
SUPERLINEAR
Stable bounded growth and the
slowing down of the pace of life
( biology and companies )
Unbounded growth and to an
accelerating pace of life
?

5. MARGIE'STRAVEL
5
M
SCALE-CHAPTER7 THE SUBLINEAR SCALE OF CITIES :
Studying the growth of the number of gas
stations with city size measured by the
population by investigating European
countries .
RESULTS :
-Straight line shows that the number of gas
stations increase with population size .
-The slope of the straight line is about 0.85 (
a little bit higher than 0,75 the metabolic
rate for organism ) = Approximately the
same value for how gasoline stations scale
across the European countries .
-The scaling is sublinear meaning that the
bigger the city the fewer the number of gas
stations needed per capita .
SYSTEMATIC
APPROXIMATELY
THE SAME
CITIES BEHAVE LIKE ORGANISMS WHEN IT
COMES TO THEIR INFRASTRUCTURE ( roads ,
electrical lines ,water , gas lines….. )
= SUBLINEAR SCALE .

6. MARGIE'STRAVEL
6
M
HOWEVER
Luis and Jose , analyzed specific metric
about urban systems across the globe :
• Only about 85% more material
infrastructure is needed with every
doubling of city size .
• A city of 10 million people typically
needs 15% less of the same
instrastructure compared with two
cities of 5 million each leading to a
significant saving in materials and
energy use. = significant decrease in
the production of emission and
pollution .
The greater efficiency that comes with
size is that the bigger the city the
greener it is and the smaller its per
capita carbon footprint .
SCALE-CHAPTER7
HOWEVER
What are the discoveries on the
socio-economic level ?

7. MARGIE'STRAVEL
7
M
SUPERLINIEAR SCALESUPERLINIEAR SCALE
The data also revealed surprising discovery
on the socio-economic level .
 The socio economic quantities:
average wage , the number of
professional people , the number of
patent produced , the amount of crime
,the number of restaurants , the GPD
have equally surprising value clustering
around 1,15 regardless of the urban
system .
 The larger the city the more the
average citizen owns produces and
consumes whether its good resources or
idea = the more innovative social
capital is created .
LARGER CITY
Higher wage
Greater
GPD ……
More crimes
More
diseases…..
Positive impacts Negative impacts
SYSTEMATICINCREASE
`` For every doubling in residents, you need only 85 percent more infrastructure, but you get 115 percent
more economic activity—and 115 percent more crime and disease ``
SCALE-CHAPTER7  THE SUPERLINEAR SCALE OF CITIES :

8. MARGIE'STRAVEL
8
M
To summarize ; the
bigger the city the
greater the social activity
the more opportunity ,
the higher the wage ,the
more diversity but at the
same time there is a
dark side and negative
aspects like increase of
crime pollution and
disease.
SCALE-CHAPTER7
1-WAGE USA
2-PROFESSIONAL PEOPLE USA
3-NUMBER OF PATENTS USA
-NUMBER OF RESTAURANTS .
Netherlands -GPD . France
The scaling of a variety of
socio-economic metrics as
a function of population size
in a number of different
urban systems showing the
remarkable similarity of their
superlinear exponents .

9. MARGIE'STRAVEL
9
M
•We typically think of each city as being unique with
its own history, geography and culture having its own
special individuality and character that we feel we
recognize however their own urban system cities are
approximately scaled versions of one another.
Much about a city is determined simply by its size .
Scaling laws are between cities
within the same national urban
system within the same country
because scaling depends on the
economy , culture and individually of
each national urban system .
eg : the overall scale of crime is
much lower in Japan than in the
united states .
The ability to be able to predict within 80 to 90%
accuracy by using the SCALING LAW .
!
SCALE-CHAPTER7

10. MARGIE'STRAVEL
10
M
2 : CITIES AND
SOCIAL NETWORK .
SCALE-CHAPTER7

11. MARGIE'STRAVEL
11
M
What are the common unifying factor
that transcends the differences and the
dynamical facilities between different
cities around the globe with different
geographies, histories and cultures?
QUESTION :Q A ANSWER :
Universality of social network structures
across the globe = the people in the
city .
To a large extent people are pretty
much the same all over the world in
how the interact with one another and
how they cluster to form groups and
communities = the human biological
and social organization and dynamics
are remarkably similar .
SCALE-CHAPTER7
Economic growth , wealth , production and
innovation .
Integration of the social network with the
physical infrastructural networks to create
the urban life .
Does city share similar conceptual
framework and mathematical
structures with biological network ?

12. MARGIE'STRAVEL
12
M
3. WHAT ARE THESE
NETWORKS ?
SCALE-CHAPTER7

13. MARGIE'STRAVEL
13
M
ANALOGY BETWEEN BIOLOGICAL NETWORK :
•Space filling: in the city road and transport
networks have to be space filling so that
every local region of the city is serviced and
also like the various utility lines have to supply
water, gas and electricity to all of its houses
and buildings.
This concept can be extended to social
network ; each person interacts with a
number of other people as well as with groups
of people in the city in such a way that
collectively their network of interactions fills
the available socioeconomic space .
SCALE-CHAPTER7

14. MARGIE'STRAVEL
14
M
ANALOGY BETWEEN BIOLOGICAL NETWORK :
•The invariant terminal units : people
and their houses ( analogue with the
cell , capillaries , leaves ….. ) .
•The network have evolved to be
approximately optimal: upgrades,
improvements, replacements and
maintenance are continually being
undertaken in cities.
•Eg : for instance when it comes to
transport most journeys whether by bus ,
train or car are undertaken with the aim
to minimize travel time or distance or
both = A trend toward approximate
optimization of the city’s network
systems.
SCALE-CHAPTER7
• On the socio-economic level , the city
structure and dynamic evolved so as to
maximize social capital by optimizing the
connectivity between individuals
= who is connected to whom, how much
information flows between them ……..

15. MARGIE'STRAVEL
15
M
4. CITIES CHRISTALLS
OR FRACTALS?
SCALE-CHAPTER7

16. MARGIE'STRAVEL
16
M
 THE CHRISTALL MODEL
The CHRISTALL MODEL is a geometric model
on how cities and urban systems are
physically configured .
 This theory developed by the German
geographer Walter Christaller based on his
personal observation of cites in southeast
Germany and it has influenced the design
and thinking of cities during the 20th century .
 According to the author this theory has a lot
in common with the rigid inorganic garden
city design of Ebenzer Howard that has
almost no consideration to the role of people
other than being economic units .
SCALE-CHAPTER7

17. MARGIE'STRAVEL
17
M
The Christall model also called the central
place theory was funded on the following
assumptions:
1- All areas have an isotropic surface
= Flat surface .
2- The population is distributed evenly
= residents are no concentrated at one
particular place .
3- The resources are distributed evenly
= No place has an advantage of
resources .
4- Similar purchasing power of all
consumers = Wealth is fairly distributed .
SCALE-CHAPTER7

18. MARGIE'STRAVEL
18
M
These assumptions when combined result in places which people enjoy the
perfect market and purchase from the nearest place to save money and time so
the theory consists of two basic concepts :
THRESHOLD
• The minimum market ;
needed to sustain the
service it is defined by the
minimum number of people
required to support this
service ; if this size is not
reached then a particular
activity will not start or it will
be closed down .
RANGE
• The maximum distance people
will travel to purchase goods
and services at an equivalent
distance ; the maximum
distance people are willing to
travel to use a service .
1 2
SCALE-CHAPTER7

19. MARGIE'STRAVEL
19
M
THE GEOMETRIC MODEL :
Transport is equally
reachable from all distance
Circular shape of market area
Circular shape results in
unserved area so we
need a series of
overlapping circular
market area
This model reduces the
market area of each
central place .
hexagon shape could fit
together edge to edge to
cover completely area and
not leave a space
unserved .
1 2 3
SCALE-CHAPTER7

20. MARGIE'STRAVEL
20
M
 The theory suggests that settlements are
regularly spaced – equidistant spacing
between same order centers, with larger
centers farther apart as compared
to smaller centers ( figure right ) .
 The market area is hexagonal shaped as
it is free from overlapping, most efficient in
both number and function
According to the writer this model
incorporates two very important features
that is shared in common with organically
evolved network despite being inorganic ;
SPACE FILLING and SELF SIMILAR .
SCALE-CHAPTER7

21. MARGIE'STRAVEL
21
M
IMPLICATION OF
CHRISTALTHEORY :
The map shows the settlements in the western
part of the state of Michoacán. The largest city
by far is Uruapan (250,000 inhabitants in 2008).
Around Uruapan are six fairly large
neighboring towns or cities. Each of these
settlements has its own corresponding market
area.
However, even though these six places are
roughly equidistant from Uruapan, they turn out
to be very different in size. For example, Zamora
(240,000) has more than four times the
population of Pátzcuaro (53,000).
Zamora is bigger because in addition to
providing services to a larger, more prosperous,
surrounding market area, it also has some
manufacturing and is on a railroad line .
SCALE-CHAPTER7

22. MARGIE'STRAVEL
22
M
 Central place theory does a good job of
explaining the number of central places at
each level and the types of services they
provide but has its own limitations. These
include the assumptions which are unrealistic.
 It is nearly impossible to have very large flat
terrain, perfect market, and absence of
preference for shopping places.
 Realistically , the resources are never equally
distributed, and some enjoy disproportionate
benefits. Same is true for purchasing power.
THETHEORY LIMITATION :
The city is actually beyond the rigid hexagonal crystalline structure of Christaller
but it is more likely a complex adaptive system akin to an organism with its fractal
like shapes .
SCALE-CHAPTER7

23. MARGIE'STRAVEL
23
M
 THE FRACTAL CITY :
•Cities are in fact approximate self-similar
fractals much like biological organism .
•Fractal dimensions are a measure of an
objects’ degree of crinkliness more simply a
major of the city’s complexity.
SCALE-CHAPTER7

24. MARGIE'STRAVEL
24
M
Analogy between a plan seed
development and the growth of
cities .
Fractal city forms at various scales. (a) London. (b) Wolverhampton. (c) New York. (d) Tokyo
SCALE-CHAPTER7

25. MARGIE'STRAVEL
25
M
• One of the most interesting use of fractal
dimension is the diagnostic barometer of
the health of a city ; the fractal dimension
of a healthy robust city steadily increases
as it grows and develop = greater
complexity = more and more infrastructure
is built to accommodate an expanding
population
• However a city’s fractal nature may not
always be so obvious from just looking at its
physical manifestations .
SCALE-CHAPTER7

26. MARGIE'STRAVEL
26
M
• The author gives an example of an entire
urban system rather than for a specific city ;
the interstate road network system of the
Unites states .
• The road system was inspired by Hitlers’s
autobahns in Prewar Germany which is
construction was motivated by defense
needs .
• Consequently the American road system
was planned to be as straight as possible in
order too minimize distance and travel times
between major cities .
• However the road system roughly
approximates a rectangular grid ( the
organic result comes from the physical and
local conditions that have to dedicate
deviation of the roads ) .
Standard map of the road system in the united state
THE ACTUAL TRAFFIC FOW
The road system becomes
an fractal system
THE PHYSICAL APPEARANCE
The road system is a
rectangular grid
SCALE-CHAPTER7

27. MARGIE'STRAVEL
27
M New York layout
SCALE-CHAPTER7

28. MARGIE'STRAVEL
28
M
HOW DOESTHE TRAFFIC FLOW ?
The author gives example with a port city
in the south of the united state Laredo ,
Texas :
1. Trucks leave the port on a regular basis
to deliver goods all over the state .
2. The sections of the streets have the
most traffic on them because all the
trucks have to use them to leave .
3. Trucks travel further away they fan out
across the country by branching off
onto other road sections
4. These branches have less and less
truck traffic on them .
A map of the flow of the interstate highway system of the united states
that we can compare with the cardiovascular blood transport system
in the biological body . The road system has been transformed to a
more interesting hierarchical fractal like structure remarkably
reminiscemt of our circulatory system .
SCALE-CHAPTER7

29. MARGIE'STRAVEL
29
M
This pattern is repeated for each city across the country ,
each city behave as pumping heart or as central place in
the jargon of Christaller .
SCALE-CHAPTER7

30. MARGIE'STRAVEL
30
M
• However , because of the absence of detailed statistics on traffic
flow for every street in the city we can’t perform analysis for other
cities , here comes the role of smart city with the promise of
countless detectors on every street corner monitoring traffic that will
eventually provide sufficient data to carry our similar analysis on all
cities and also reveal metrics that are crucial for planning purposes .
• We need two approaches if we are to accomplish huge challenge of
understanding cities ; the phenomenological traditions of the social
scienes , geography and urban planning and the analytic ,
mathematic traditions of physics .
SCALE-CHAPTER7

31. MARGIE'STRAVEL
31
M
THANKYOU
SCALE-CHAPTER7
감사합니다