Thursday, August 14, 2008

Notes on Traffic Gridlock, Game Theory and the Prisoner's Dilemma

Photo Caption: Katipunan traffic gridlock (Source: Ateneo de Manila University Physical Plant Office)

Last Friday, August 8, 2008, a traffic gridlock occurred in Katipunan Avenue, Quezon City in the vicinity of Miriam College and Ateneo de Manila University. (See related link: )

What is a gridlock?

Here are some notes that I gathered from a Wikipedia article:

"1. Gridlock is a term describing an inability to move on a transport network. The term originates from a situation possible in a grid network where intersections are blocked, prohibiting vehicles from moving through the intersection or backing up to an upstream intersection.

2. The term gridlock is also widely used to describe high traffic congestion with minimal flow (a "traffic jam"), whether or not a blocked grid system is involved. By extension, the term has been applied to situations in other fields where flow is stalled by excess demand, or in which competing interests prevent progress.

3. The traditional form of gridlock is caused by traffic heading in one direction blocking cross traffic at an intersection. In many jurisdictions, drivers are prohibited from entering an intersection if they cannot clear it before the traffic light turns red. If drivers follow this rule of the road, gridlock will be prevented and traffic will only be slow in the direction that is actually congested. One method of reducing gridlock is to aggressively enforce penalties for vehicles that block intersections.

4. Another type of gridlock can occur during traffic surges between highway on-ramps and off-ramps located within a quarter mile of each other. Traffic exiting the highway may back up and block the entering vehicles.

5. Gridlock is sometimes cited as an example of the prisoner's dilemma (from game theory). Mutual cooperation among drivers would give the maximum benefit (prevention of gridlock), but this may not happen because of the desire to maximize one's own benefit (shortest travel time) given the uncertainty about the other drivers' commitment to cooperation."


To an applied mathematician and computational scientist like me, studying traffic dynamics is quite interesting because traffic is considered a nonlinear and complex phenomenon. Modeling and simulation of traffic dynamics is a useful tool that the Metropolitan Manila Development Authority (MMDA) can utilize in the management of traffic in Metro Manila, particularly in the Katipunan area.


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