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August 2009
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From Anarchy to Order

Have you ever been driving home during rush-hour wondering why it is taking so long to get through the traffic light? Through a busy interchange? Only to see it open up and you travel along smoothly for a few minutes or the rest of the way to your destination. Frustrating as it may be it’s the reality because we are inherently selfish creatures!

A friend of mine passed me an article at work, The Price of Anarchy in Transportation Networks: Efficiency and Optimality Control. It is a little technical and ‘mathy’ but I was surprised at how easy it was to follow.

The abstract really captures the essence of the article:

Uncoordinated individuals in human society pursuing their personally optimal strategies do not always achieve the social optimum, the most beneficial state to the society as a whole. Instead, strategies form Nash equilibria which are often socially suboptimal. Society, therefore, has to pay a price of anarchy for the lack of coordination among its members. Here we assess this price of anarchy by analyzing the travel times in road networks of several major cities. Our simulation shows that uncoordinated drivers possibly waste a considerable amount of their travel time. Counter-intuitively, simply blocking certain streets can partially improve the traffic conditions. We analyze various complex networks and discuss the possibility of similar paradoxes in physics.

Blocking Streets Improves Traffic Conditions

Imagine in Toronto we blocked several of the east-west streets in the central business district and forced traffic to pick a major north-south route and stick with it? Imagine all cities with more efficient major arteriole roads. The theory from the authors is that overall travel times would improve. Inevitably some individuals would suffer a delay from this new transportation grid, but the overall effect would be a decrease in traffic times.

Traffic would be forced to stick with a route. It would minimize the number of right and left turns, which cause traffic to slow. Traffic patterns would be improved. Fewer people would be on the residential streets, making them safer. And you would arrive to your final destination faster.

But given the nature of Toronto, and some other similar cities, there would need to be some access to east-west streets to access the neighbourhoods. It would be about finding a balance; it must still be attractive to live in the city with safe streets and efficient road networks.

It would be interesting to see this in action. I would like to see them try this on Avenue Road, Yonge Street or Mount Pleasant Boulevard in Toronto; three major north-south routes that always seem jammed because there are not many dedicated left- and right-turn lanes. Perhaps with improved travel times, surface route public transit would also become more attractive allowing more people to choose to leave their car at home.