Closing Down 42nd Street – Braess’ Paradox
Source: http://www.nytimes.com/1990/12/25/health/what-if-they-closed-42d-street-and-nobody-noticed.html?mcubz=1
Other blog: https://blogs.cornell.edu/info2040/2017/09/17/braesss-paradox-in-the-real-world/
Disclaimer: After searching through the website, I found that a previous student had also posted a blog concerning this article. However, I will post my own interpretations of the article and offer a new perspective of the topic at hand.
On April 22nd of 1990, New York City’s Transportation Commissioner decided to shut down 42nd Street. Though many predicted this to yield disastrous traffic conditions, as 42nd Street is already always a congested street, traffic flowed better on that day instead. This was an example of Braess’ Paradox– having a road open did not necessarily constitute a better flow of traffic. In fact, it yielded the opposite of effect. As the article explained: “the reason is that in crowded conditions, drivers will pile into a new street, clogging both it and the streets that provide access to it.” However, it is important to note a fundamental principle of Braess’ Paradox. The paradox only comes into play for congested networks! Dr. Joel E. Cohen, a mathematician at Rockefeller University explains that “each traffic network must be analyzed on its own.” Moreover, Dr. Cohen also observed a derivative of Braess’ Paradox in which “when you add more delays along a route, more people use it.”
Braess’ Paradox really stood out to me when we discussed it in class. As the other blog writer had written, “it seemed very counterintuitive at first.” But what surprised me even more was what I interpreted to be Braess’ Paradox at the end of the day– a situation that arises due to human selfishness. When we did the example of Braess’ Paradox and Nash Equilibrium in class, it surprised me that the Nash Equilibrium in fact increased the travel time despite the fact that there were better routes out there. If the drivers had all cooperated with one another and worked out a more communal strategy, then everyone could reap from the benefits of coordination. However, this clearly is not the case in the real world today as it is impossible for drivers to coordinate with one another. But this had me thinking: what about in the future when we have autonomous cars? Will the computers in the car be able to communicate and coordinate with one another to optimize the travel time for all parties? And this is when the beauty of this class dawned upon me. One engineer, sitting in that lecture hall, can be so enthralled by such a paradox. He/she may go on to build autonomous vehicles and develop a program to ameliorate Braess’ Paradox. From one lecture, this world can be shaped to be a utopia we have envisioned.