Planning for the Future: Using Braess’s Paradox for Urban Planning
https://tribune.com.pk/story/2342297/urban-planning-for-cars-in-capital
With global populations steadily growing, wisely investing in infrastructure has never been so important. Urban planning decisions are difficult to make and are often made under the pressure of unhappy citizens. As this article discusses, in Islamabad (the capital of Pakistan), urban planners who designed the city failed to account for urban sprawl and a rise in car ownership.
Now, in 2022, the city is nearly impossible to live in without a car. The Islamabad Expressway is constantly crowded, and has made parts of the city unlivable. There is a high population density on the outskirts of the city, so every commuter trying to get into the city must use a car. Furthermore, the only affordable housing that exists is near the expressway since no one else wants to live there. There are multiple poor urban planning decisions at play: tolls, which can contribute to the payoff in a Nash Equilibrium, are not being used, and the proposed plan to decrease traffic on the expressway is to add more lanes to the road in an effort to decrease density.
It is easy to think about the conundrum in a methodical way, but it is important to keep in mind how taxing this is to people who live in Islamabad. Roadways should make travel easier, but instead it is decreasing quality of life by increasing CO2 emissions from cars stuck in traffic. As the article notes, “…infrastructure should save travel time but instead people invest the travel time saved in traveling a longer distance.”
In class, Braess’s Paradox was discussed. Initially, it can seem obvious that adding more routes to get to a destination will make the overall travel time shorter, and make roadways less congested. This is the mistake that the urban planners of Islamabad are making. But, through examples, we saw how adding a road (or adding a strategy) can make the Nash Equilibrium worse for everyone else. That is to say that adding a road can make every drivers’ travel time increase. In Islamabad specifically, this may cause more commuters to try to drive to work or incentivize travelers to go longer distances. We cannot guarantee that only certain drivers will take certain routes, so when drivers stray from the expected course in an attempt to shorten their travel time, new roads can cause further congestion on old roads which were not built to deal with this new level of traffic. Although this is a problem that needs to be solved quickly, it is important to not forget the paradox at play and adjust solutions accordingly. Implementing a toll on some roads, or expanding public transportation could save the city of Islamabad from traffic-induced chaos.