Building New Roads Does Not Always Lead To Less Congestion
According to a study conducted by two University of Toronto professors and published by the American Economic Review, buildings roads to cure congestion is an exercise in futility.
The University of Toronto professors described a number of reasons why building more roads results in more driving despite what our common sense would tell us. Amongst those, they described that people drive more when there are more roads to drive on, commercial driving and trucking increases with the number of roads, and , to a lesser extent, people migrate to areas with lots of roads. Although there are many schools of thought concerning the issue of minimizing travel time and optimizing our nation’s commutes, there is one thing not up for debate: the economic impact of traffic is immense. In fact, in 2001, the average American household spent nearly three hours per day in a car. This is all downtime that could have been spent doing anything other than “nothing” (granted, some folks are remarkably skilled at talking on the phone while driving, but that’s illegal in many states, anyway!). One solution that always makes its way into the conversation when considering congestion is transit. Although Duranton and Turner (the University of Toronto professors) didn’t find that transit reduces congestion it doesn’t mean that metro areas should build transit a a way to maximize the efficiency of their transportation networks, they say. Although buses and trains go a long way in reducing our carbon footprint and are environmentally friendly, the study shows that transit does not reduce Vehicle Kilometers Traveled, only that it is a good way to get more “person-miles” out of roads, citing that the spaces that are cleared up when people switch from their cars to buses will consequently be filled by other people with their own cars.
The reasoning behind why new roads do not always lead to reduced congestion can be reduced to a game of players, payoffs, and strategies. We can put on our Nash goggles and investigate this phenomena with game theory tools. Simply put, providing people with more options can, sometimes, lead to negative results. Take four cities A, B, C, and D. City A has 100 citizens that need to get to city B, all of which leave the city at the same time. To get from city A to city B, the state has put two highways, one of which passes through city C, and one of which passes through city D. The time to get from city A to city C is the number of people on the road divided by 100; the time to get from C to B is 1.3 hours; from A to D is 1.3 hours; and D to B is the number of people on the road divided by 100. Now, the shortest possible time to get from A to B is 1.31 hours. However, the Nash Equilibrium in this example is when half the people take road ACB, because none of the participants in this scenario would be better off switching their strategies. However, when you introduce a new road, Z, connecting city C to D (one way), which takes a negligible amount of time to cross, the Nash Equilibrium is now for everyone to take ACDB, since everyone would be better off staying on that road than switching strategies.
So, although the real life example includes different factors not considered in our example, we can see how the process of building new roads does not always lead to reduced congestion.