They're still using Turner's paper about "induced demand" but when you look at the data, it doesn't really support the hypothesis: https://www.cato.org/blog/de

They're still using Turner's paper about "induced demand" but when you look at the data, it doesn't really support the hypothesis: https://www.cato.org/blog/debunking-induced-demand-myth https://www.cato.org/blog/debunking-induced-demand-myth The paper compared daily kilometers of interstate highway driving with lane kilometers of interstates in the urbanized portions of 228 metropolitan areas. In the average metropolitan area, it found that between 1983 and 1993 lane miles grew by 32 percent while driving grew by 77 percent. Between 1993 and 2003, lane miles grew by 18 percent, and driving grew by 46 percent. That's hardly a "perfect one-to-one relationship." The paper also calculated the elasticities of driving in relationship to lane kilometers. An elasticity of 2 would mean a 10 percent increase in lane miles would correspond with a 20 percent growth in driving; an elasticity of 1 would mean that lane miles and driving would track closely together. The paper found that elasticities were very close to 1 with standard errors of around 0.05. Even though this is contradicted by the previously cited data showing that driving grew much faster than lane miles, this is the source of Turner's "perfect one-to-one relationship." Looking at the same years as Duranton & Turner, in more than 90 percent of urban areas, driving grew far faster than lane miles. On average, driving grew more than twice as fast as lane miles. But in Boston between 1983 and 1993, freeway capacities grew by less than 1 percent, while driving grew by more than 35 percent. In Madison, capacities grew by 35 percent, while driving grew by less than 20 percent. The wide range in differences between urban areas suggests that, not only are Duranton & Turner's elasticities wrong, their standard errors are far too low.