“Roads Create Traffic” Debunked

You know that “creating more public roads just creates more traffic” talking point trotted out by people who want to ban your car?

Yeah, not so much.

The first two thirds of the video covers other topics, like how economies of scale don’t necessarily drive down prices uniformly, and as you scale, you incur new costs that might make a product less profitable. (One example is China’s overbuilt high speed rail network.)

The last portion deals with the “roads create traffic” myth, directly delving into the study the anti-road types cite:

  • “What [building new highways[ doesn’t do is create entirely new demand.”
  • “New roadways, especially interstates, tend to be more direct, and can take a larger volume of traffic than alternative routes through urban areas.”
  • “The study itself has also been widely criticized for making assumptions that other economists were not able to replicate in follow-up studies.”
  • “Its methodology was also questionable. It measured interstate kilometers traveled. Building out more interstates might make people use those roads more, but that doesn’t mean that there are more cars overall, because a lot of that traffic would have been taken away from non-interstate roads, which were not measured in the study.”
  • “More roads won’t create more congestion unless they are designed very poorly, and reducing the supply of roads won’t ease congestion, either.”
  • The original study authors didn’t even suggest reducing roads; they were in favor of congestion charges.
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    5 Responses to ““Roads Create Traffic” Debunked”

    1. Pettifogger says:

      I’ve heard the more-roads-equals-more-traffic malarkey before. Being from Texas, I suggest they raise cash with a private placement and then buy up all the land around Iraan. Then they can build a big freeway to bring people flocking in. if what they’re saying is true, they’ll make a killing on skyrocketing land values. Nobody has believed in their theory enough to give Iraan a try.

    2. M. Rad. says:

      The roads-create-traffic effect is the hallmark of a /successful/ infrastructure project. I remember when the proliferation of dial-up internet would saturate the ISP T1 backhaul links on Saturday mornings, so your 28.8 kbit modem was not even the bottleneck. Would you want to go back to mail-order catalogs and 10c/min long-distance? Early mobile data networks got saturated, too, but would you want to go back to syncing a Palm Pilot to your desktop PC or fetching email from dial-up on an airport payphone? Streaming video stressed home broadband, but clearly beat mail-order pr0n DVD…uh…trips to Blockbuster. Electric grids strain in the summer, but make A/C possible. And on and on and on.

      Simply put, congested highways are the price of escaping poor living conditions of central cities and are judged to be worth it by those who use them. By contrast, things like light-rail, so enamored by urban planners, often have low ridership, and that is the hallmark of a boondoggle.

      The two points in the video are related in a way the creator seems to miss. Congestion implies that highway capacity is valuable enough that users are willing to pay the price to build capacity beyond the optimum economy of scale, and hence the need for congestion pricing.

    3. tim maguire says:

      “More lanes makes traffic worse” is illogical for the same reason “hot water freezes faster than cold water” and “heavy objects fall faster than lighter objects” are illogical.

      If traffic is limited by congestion, which causes spillover demand in the surrounding streets, then adding more lanes might bring in more cars (some people who chose side streets will now choose the highway), but the forces that led to them choosing side streets under the starting conditions are still in play–the mere fact of more lanes on the highway will not cause them to choose the highway if the side street is still faster.

      Ergo, the worst possible outcome is the highway gets only a tiny bit better while side streets are relived of some overflow traffic.

    4. Garrett Stasse says:

      Anyone who thinks more roads is stupid should spend time driving around the Jersey Shore. The region was built for half the population it has now. Add millions of tourists and you get locals like me wishing New York had nicer beaches and civilized people.

    5. Howard says:

      Is “induced demand” not true? I wouldn’t dismiss it too quickly.

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