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Building Bigger Roads Actually Makes Traffic Worse

What’s Up With That: Building Bigger Roads Actually Makes Traffic Worse


Earlier in the semester, the topic of traffic and how it relates to the Networks course at Cornell University was discussed at great length. Ideas about Nash equilibriums, travel times, payoffs, and the Braess Paradox were all used to build students’ understanding of the topic and draw on some very interesting concepts from the real world.

“What’s Up With That: Building Bigger Roads Actually Makes Traffic Worse”, an article by Adam Mann from Wired, further draws on some of the concepts discussed in class, relates these concepts to very real life examples and even adds some more interesting examples that supplement the topics from lecture. One major point that Mann made in his article was that in certain areas, roads will always be congested, even when one (or more than one) lane is added or taken away. Interestingly, though, the traffic on these roads will barely change at all when these lane changes are made. In fact, Mann mentions many cases where roads were deleted and replaced with other things like parks or smaller roads in San Francisco, South Korea, and Paris, and saw little change in the amount of traffic and congestion on the overall system of roads. Studies cited in the article show that if there are more roads to use, more people will use them, and vice versa – as long as monetary costs remain zero. Mann finishes up his article by introducing congestion pricing, a concept that could subconsciously convince people to find a better equilibrium, by making the roads in cities with “a great deal of underused capacity” more enticing by raising the prices of the historically traffic-ridden roads.

At first glance at the title of the article, it seems like the main objective of Mann’s piece was to discuss real life examples of the Braess Paradox, a concept that explains how adding a road to a road network might lead to a higher equilibrium travel time, instead of the desired effect of lowering the travel time. Although it does discuss this paradox at some length (how the addition of roads does not affect the equilibrium travel time), the article goes deeper into payoffs and costs. Instead of payoffs being times, Mann equates payoffs to tolls and paid parking. Here, Mann’s mentioning of the congestion pricing makes some roads more appealing to certain drivers at certain times by offering a lower price for traveling on less congested roads. In class, the payoffs were limited to travel time, making less travel time a better payoff. But, with the introduction of this new factor, it forces people to use roads more wisely and more efficiently, ultimately lowering the equilibrium travel time. Looking forward, it will be interesting to see if this congestion pricing becomes more widespread and helps with the mitigation of traffic, rather than just the current policy of adding, taking away, and re-designing roads.


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