Unfortunate news: Traffic is here to stay
Everyone has had the unfortunate experience of sitting in traffic for hours. Like that time when you’re pretty sure your car has moved only 10 feet in an hour? You probably have found yourself thinking “Gee, wouldn’t it be great if they could make these highways wider? More lanes, less traffic.”
Not necessarily.
Adam Mann from Wired.com posted an article about some of the unforeseen consequences of adding more lanes or even more connecting roads to highways. The goal is to include these additions to increase the flow of traffic. But, in many cases, this can backfire. Mann calls this phenomenon “induced demand”, colloquially defined as the increase of “supply of something (like roads) make[ing] people want that thing even more”. This induced demand overtakes the supply of roads available– causing even more traffic than what was originally there!
We have discussed, in Networks, the effects of including a new connecting highway in a network of pre-existing highways. The appeal of a new road attracts more commuters, thus increasing everyone’s travel time. This phenomenon is called “Braess’s Paradox”. Mann’s article brings up another occurrence in which Braess’s Paradox occurs– increasing the number of lanes in highways. Mann mentions two economists, Matthew Turner (from the University of Toronto) and Gilles Duranton (from the University of Pennsylvania) who came up with “the fundamental law of road congestion”: New roads will create new drivers, resulting in the intensity of traffic staying the same. This applies, also, to the creation of new lanes. Wherever there is another space for another vehicle, as long as commuters gain knowledge about that feature and there are enough commuters available, the level of traffic will either stay the same or increase.
So, unfortunately, traffic is here to stay. So, the advise I have for those finding themselves stuck on a highway at standstill: pack a snack!
What’s Up With That: Building Bigger Roads Actually Makes Traffic Worse