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This study investigates how individual shopping travel behavior reshapes the format of our cisites using Agent Based Modeling and Simulation
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A Story about “Sustainability”
How do we change the world
Jing (Eric) Du
2/17/2012
Page 2
What is “Sustainability”?
Source: www.un-documents.net/wced-ocf.htm
“(Sustainability) is development that meets the needs of the
present without compromising the ability of future generations
to meet their own needs.”
-- United Nations, March 20, 1987
Page 3
“Mixed land use is critical to sustainability”
Sustainable Urban Forms– Neotraditional Dev. :mixed land use; diversity
– Compact City :mixed land use; density; diveristy; compact; tranportation
– Urban Containment :mixed land use; diversity; compact; transportation
Mixed Land Use– Diverse functional land uses in a given area
– Reduce auto-travel
– Economic, Environmental and Social benifits
Page 4
But the reality...
Left to right: New York, East Lansing, Victoria
Page 5
Why are most real world cities “unmixed”?
“Traditional rigid zoning”
Breheny 1993; Masnavi 2000; Beatley 2000; Wheeler 2002; and ...
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But...are they right?
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Human Behavior
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A simple story: go shopping!
Attractiveness: size, price...
Income
Gravity model
Distance
Page 9
A simple story: go shopping!
Page 10
An Artificial World: parameters
Parameter Value Explanation
Grid 50*50 2,500 cells
Simulation time 200 200 ticks or steps
Initial number of households 200 ea
Initial number of stores 20 ea
α [0.0, 6.0] Parameter of gravity model
β [0.0, 6.0] Parameter of gravity model
Store operation expense N (0.2, 0.05) Follow a normal distribution
Store size Pareto (500000, 2) Follow a Pareto distribution
Household purchase N(500, 100) Follow a normal distribution
Initial store’s cash reserve size Set the initial cash reserve same as store size
Expand threshold 2*size If cash_reserve >2*size, then expand
Baseline 0.3*size If cash_reserve<0.3*size, then quit the market
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Snapshot: when α=1.0, β=[0.25, 6.0]
Monte Carlo process
50 artificial cities
625 different parameter combinations
31,250 simulations
114 hours in two computers
Page 12
Does mixed land use really lead to less transportation?
Page 13
Less transport due to the increase of walkability?
0.25 0.
5
0.75
0000
0000
0000
4 11.
25 1.5
1.75 2
2.25 2.
52.
75 33.
25 3.5
3.75 4 6
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
Transportation
Walk distance Total distance Car distance
- The freqency of auto-travel doesn’t decrease;
- The frequency of nonauto-travel doesn’t increase;
- But the distance of each auto-travel is significantly reduced.
- Proved by many emperical studies (Kitamura et al. 1997; Boarnet and Sarmiento 1998; Boarnet and Crane 2001)
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Impacts of human behaviors on urban form?
Page 15
Impacts of human behaviors on auto-travel needs?
Page 16
Impacts of human behaviors on walkability?
Page 17
Why do most cities today have concentric areas?
Page 18
Why do most cities today have concentric areas?
Page 19
Lessons learned?
Mixed land use can lead to less transportBut it’s attributed to the reduction of each auto-travel distance, instead of the increase of walkability
Human behavior shapes our city: The improvement of transportation technology and efficiency makes people willing to drive, and in turn today’s cities are more “concentrated”
Sustainability is a complex issue
The application of computer simulation
Page 20
Discussion
Behavior
Environment
Society
Economy
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