What’s Up With That: Building Bigger Roads Actually Makes Traffic Worse
Source: https://www.wired.com/2014/06/wuwt-traffic-induced-demand/
What’s Up With That: Building Bigger Roads Actually Makes Traffic Worse
The writer reminisces childhood memory of asking why can’t people build more roads to reduce traffic; however, he later realized that it’s “the roads themselves that cause traffic.”
The article then starts by introducing the concept called induced demand, which implies increasing the supply of something makes people want the thing even more. He refers to a study conducted by two economists—Matthew Turner of the University of Toronto and Gilles Duranton of the University of Pennsylvania—about how many new roads and highways were built in different cities in US in between 1980 and 2000, and the total number of miles driven on the roads during the time period. The study concluded that new roads don’t solve traffic congestion but make it worse. New roads bring more drivers, which cause the same thing. This situation seems familiar…and yes, it is about traffic equilibrium.
The author introduces another example about traffic equilibrium. He refers to Paris’ persistent policy to dramatically reduce the number of roadways. The result was in fact contrary to our instinct—driving in Paris is still bad after the downsize, but “it’s not much worse.”
However, if so, how can we solve the problem of traffic congestion?
The article mentions congestion pricing. The congestion pricing is raising the price of tolls or creating tolls on roads with high demands. Many case studies have shown that congestion pricing has worked successfully.
All of these topics—induced demand, traffic equilibrium, and congestion pricing (toll)—relates back to the topic discussed during the lecture. Let there are two different paths: A-C-B and A-D-B.
If another road connected A directly to B gets built, people’s instinct will say that traffic congestion will be solved. However, as the article elaborates, it causes induced demand. People, including people who used to drive on another roadways, move to the newly built roadway—which causes more traffic. Moreover, the lecture briefly mentions about creating toll to solve the problem. However, even though putting toll is said to be useful, the remaining problem is of whether people agree to pay for what was previously free…