Dallas, built for cars. (photo: Neff Conner/Flickr)

More Roads Just Mean More Traffic

We can't build our way out of traffic congestion.

An alert FrontBurnervian passes along a new Wired story that succinctly explains the phenomenon of “induced demand” when it comes to highways. (Yes, this is another post about the debate over Interstate 345.)

You’ve likely heard the phrase on this blog before, but to explain again: the evidence suggests that as you build more roads in a city, the number of miles driven by the people of that city increases at the same pace. Traffic congestion therefore remains constant, because making driving easier just leads to more drivers.

The Wired piece points out what you’ve also heard argued on this blog previously: that in other cities, like Seoul and San Francisco and Paris, highway capacity has been substantially reduced and traffic didn’t get worse, while other elements, like pollution levels, actually improved.

But then how could we decrease congestion?

Turner explained that the way we use roads right now is a bit like the Soviet Union’s method of distributing bread. Under the communist government, goods were given equally to all, with a central authority setting the price for each commodity. Because that price was often far less than what people were willing to pay for that good, comrades would rush to purchase it, forming lines around the block.

The U.S. government is also in the business of providing people with a good they really want: roads. And just like the old Soviets, Uncle Sam is giving this commodity away for next to nothing. Is the solution then to privatize all roads? Not unless you’re living in some libertarian fantasyland. What Turner and Duranton (and many others who’d like to see more rational transportation policy) actually advocate is known as congestion pricing.

Trouble is voters don’t like congestion pricing — paying for something that used to be free — so that may be a difficult sell. Another possible solution?

Parking in most cities is far cheaper than it should be, and it’s too often free.

“Because it’s free, people will misuse it and it will be full all the time,” said Duranton. Drivers searching for parking contribute significantly to road congestion. “There are some estimates that say in the central part of cities up to 30 percent of driving is people just cruising around for parking,” Duranton said.

Increasing the price of a parking spot when demand is high would encourage people to leave sooner, letting more drivers occupy the same spot during the day. San Francisco did exactly this starting in 2011 and the results have been a boon to retailers because more customers are able to park in front of their stores. And because prices go down when demand is low, the program has actually saved motorists money.

I’ve said it before: You want me off the road and on the bus to work each day? You’re going to have to make me pay a lot more to park downtown.


  • Bobtex

    The reason for the breadlines in the Soviet Union was not that people would rush to buy bread because the price was too low–the reason was that the supply of bread was totally inadequate. Would there have been breadlines if the supply had been adequate? Probably not.

  • Colin1497

    Fuel taxes need to increase substantially. They’re used to support our infrastructure and have not been increased to keep pace with inflation or infrastructure needs. Increased fuel taxes would help to correctly price the cost of driving, which would help drive down congestion. Increased fuel prices would also assist in driving people towards cars that are smaller, which would reduce fuel consumption, but would also reduce parking needs, though I guess easier parking drives things the wrong direction…