1. Agent-Based Modeling Simulations for
Solving Pakistan’s Urban Challenges
Dr. Hilton L. Root, Professor of Public Policy
Dr. Andrew T. Crooks, Assistant Professor
Ammar A. Malik, PhD Student
School of Public Policy, George Mason University, USA
2. Towards an Urban Future
• Cities play a critical role in our lives, providing
habitat for more than half of the world’s population
o Expected to increase to 70% by 2050
o Creating acute pressure on housing, congestion, urban
sprawl etc
• Understanding such systems is extremely complex.
o Represents “…one of the major scientific challenges of our
time” (Wilson 2000)
• Focus has shifted to a bottom-up approach to
urban systems
o One such approach is Agent-Based Modeling (ABM)
3. What is Social Simulation? (I)
We use simulation to represent
cognitive and organizational
bases of decision making that
shape the emergent results of
interactions between groups of
agents.
Schelling’s Segregation Model
• Small preference for one’s same-
color neighbors can lead to total
segregation.
• Behavioral Rule: If you are in a small
minority (<25% neighbors of the same
color), you are unhappy and will try
to move.
4. What is Social Simulation? (II)
Example below demonstrates how traffic jams can
form without any incident. Each car is an agent that
follows a simple rule set:
• If there’s a car close ahead, it slows down.
• If there’s no car ahead, it speeds up.
5. What is Social Simulation? (III)
Researchers from Japanese
universities put 22 vehicles on a
230-metre single-lane circuit:
• 22 cars equally spaced on a
230m single lane circle.
• Drivers asked to cruise steadily
at 30km/h.
At first, the traffic moved freely
• Disturbances and clusters
soon appear, causing cars to
slow or stop.
• Cars at front of the cluster can
accelerate at 40km/h, but
these join another jam. Source:
http://www.youtube.com/watch?v=Suugn-p5C1M
New Scientist Article:
http://technology.newscientist.com/article/dn13402
6. Modeling Urban Pakistan
• The diagnosis: Pakistan’s urban spheres lack
creativity and have poor connectivity
• Our Main Research Questions:
o What key underlying factors are inhibiting creativity in
Pakistani cities?
o What is the relationship between physical and social
connectivity and creativity?
o Policy Question: what can be done to improve the
situation?
• Transferring models and scenario generation know-
how to Pakistani planners through trainings
7. Agent-Based Model of Karachi
• Karachi’s large share in GDP and tax revenues
• Agents – mostly human subjects defined by their
role in society, e.g. creative class, investors
• A set of relationships – capturing interdependencies
and linkages
• Rules of interaction – basic structure of the model
• Demographic and spatial data from the real-world
8. Karachi Creative Clusters Model
• Inspiration from Richard Florida’s theory of creative class
• Inputs: inclusiveness, economic opportunities, rental rates,
political stability, talent, technology and tolerance
• Outputs: urban density, human capital, patented
innovations,
9. Economic Disparity Model Interface
Output
Input Environment Parameters
Parameters
Economic Disparity Model NetLogo Interface (Felsen and Wilensky 2007)
10. Concluding Thoughts
• ABMs allow “theory building” and “hypothesis
generation” (Barros 2012)
• For example, impact of commercializing and
rezoning state-owned land along Mall Road Lahore
• ABMs are planning support systems, not for
accurate normative predictions
• Project will hopefully generate a new narrative for
Pakistan’s daunting urban challenges
11. Agent-Based Modeling Simulations for
Solving Pakistan’s Urban Challenges
Dr. Hilton L. Root, Professor of Public Policy
Dr. Andrew T. Crooks, Assistant Professor
Ammar A. Malik, PhD Student
School of Public Policy, George Mason University, USA
Editor's Notes
As focus has shifted from modeling cities from the aggregate to the individual, ABM has become an increasingly used tool to explore such systems Slums are an ideal example of how location decisions of individuals affect the overall form and function of cities constrained by many social, political and socioeconomic factors
One simple example Add a real life segregation picture for a city!! Add traffic simulation!! Schelling statement: Most modelling techniques are based on the notion that an equilibrium state is the norm, while simulations do not have this bias. Instead of trying to create a model that requires a full understanding of the highly complex outcomes of processes, simulation allows us to understand the decision rules of a small number of individual actors. Simulation models are very good at incorporating time and space, especially when tied to a geographic information system.
- ABM is a new modelling paradigm which allows us to explore the interaction of many individuals and how these individuals interact to form more aggregate phenomena. In essence there are two components for agent-based modelling that of the agent and the world that they inhabit. Ie the artificial world. What distinguishes these agents from other modelling approaches is that individuals are not centrally governed. They have their own rules therefore dictate their own behaviour, they are dynamic and interact with each other and their environment and are capable of modelling processes from the bottom up. Stress that each car is an agent. This application highlights how simple rules applied to many individuals (such as microscopic variables of acceleration and speed related to position) can lead to more macroscopic phenomena, Such models allow us to gain insights into urban phenomena. With this type of computer simulation, its open, its not a black box like traditional urban models. We know what is going on inside of these urban models
Cars started off at equal intervals 22 vehicles on a 230-metre single-lane circuit Drivers were asked to cruise steadily at 30 kilometres per hour, and at first the traffic moved freely. But small fluctuations soon appeared in distances between cars, breaking down the free flow, until finally a cluster of several vehicles was forced to stop completely for a moment. That cluster spread backwards through the traffic like a shockwave. Every time a vehicle at the front of the cluster was able to escape at up to 40 km/h, another vehicle joined the back of the jam.
Cities should be melting pots of creative individuals, those interactions aren’t happening in Pakistan Attempt to understand how microscopic behaviors/interactions lead to these larger problems Value Addition: linking creativity with connectivity through focus on urban form and function Webinars/Skype Sessions and training modules are possible, caterig
ADB (2005) reports the city handles 95% of all foreign trade, 30% contribution to manufacturing, 90% head offices of bank/corporates, 20% contribution to GDP, 25% revenue share to Islamabad and 40% to Sindh government Creative Class includes creative entrepreneurs, artisans, musicians and so on Power of ABMs is that we can bring theories into the complex real-world simulation environment for hypothesis generation and testing
For example, modeling impact of revamping zoning, commercializing residential establishments in CBD area – ABMs will capture second and third order outcomes hence there are unending possibilities for “creative imagination” exercises In the example of Lahore, model will tell us the future urban form of Mall Road as well as its impact on employment, GRP, economic structure & so on People in Pakistan must evolve their thinking and consider an alternative urban form and function, they must realize that providing more roads & flyovers will not improve our cities, we must consider walkability, mixed land-use and so on
