Braess’ Paradox in Reverse
This article discusses the repercussions of the closure of the Alaskan Way Viaduct, a major highway, in Seattle. About 90,000 vehicles trekked the Viaduct every day, leading many to believe that traffic in the surrounding area would significantly worsen following its closure in January. However, despite all predictions, overall commute times in Seattle were reported to only increase ever so slightly. While not very much data has been recorded and released yet, researchers believe there has been a notable uptick in bicycle use, water taxi use, and public transit use. Somewhat surprisingly, however, foot traffic and vehicle traffic both appeared to see slight decreases following the closure, defying the expectations of experts.
While experts in Seattle may be surprised to hear this outcome, students of INFO 2040 may not be. As discussed in lecture, Braess’ Paradox states that adding a path to a traffic network can actually increase travel time. This would be due to travellers flocking to the new path in the belief that it would decrease their commute times. However, they fail to account that other drivers will do the same, creating congestion that ends up increasing commute times. Consequently, this principle would also imply that removing a path from a traffic network can decrease the travel time for people in the network. This is exactly what happened in the case of the Alaskan Way Viaduct. Instead of people flocking to a new route, the 90,000 daily users of the Viaduct were dispersed across a number of different travel routes, including some abandoning their cars altogether in favor of bicycles, public transit, or water taxis as previously mentioned. As a result, we see that Braess’ Paradox not only applies in real life settings, but also functions in reverse.