Removing Roads and Traffic Lights



Removing Roads and Traffic Lights

Source: just happened upon an interesting article published in Scientific America.  A mathematician in the 1960’s, Dietrich Braess, discovered a paradox:

in a network in which all the moving entities rationally seek the most efficient route, adding extra capacity can actually reduce the network’s overall efficiency

A real life test of this paradox played out when

planners in Seoul tore down a six-lane highway a few years ago and replaced it with a five-mile-long park, many transportation professionals were surprised to learn that the city’s traffic flow had actually improved, instead of worsening.

The Scientific America article points to an article by Michael Gastner in the Physical Review Letters, whereby this computer scientist and his colleagues explains

that drivers seeking the shortest route to a given destination eventually reach what is known as the Nash equilibrium, in which no single driver can do any better by changing his or her strategy unilaterally. The problem is that the Nash equilibrium is less efficient than the equilibrium reached when drivers act unselfishly—that is, when they coordinate their movements to benefit the entire group.


the researchers found that the price can be high—selfish drivers typically waste 30 percent more time than they would under “socially optimal” conditions.

It continues to describe the solution to this paradox is to reduce the numbers of roads, thereby limiting the choices motorists have to “optimize” and forcing them to make more socially conscious decisions.   They go even farther to posit what we really need is more anarchy, mix pedestrians, cyclists, and motorists together with the idea being

the more uncomfortable the driver feels, the more he is forced to make eye contact on the street with pedestrians, other drivers and to intuitively go slower

Sure sounds like a good argument for complete streets!  Not to mention, it could sure help our State’s financial woes if it had fewer streets to maintain.


  • Victor Martelle
    Mar 1, 2011 at 6:24 pm

    "Q: You write, "The truth is the road itself tells us far more than signs do." So do traffic signs work?

    A: We’ve probably all had the somewhat absurd moment of driving in the country, past a big red barn, the pungent smell of cow manure on the breeze, and then seeing a yellow traffic sign with a cow on it. Does anyone need that sign to remind them that cows may be nearby? To quote Hans Monderman, the legendary Dutch traffic engineer who was opposed to excessive signing, "if you treat people like idiots, they’ll act like idiots." Then again, perhaps someone did come blazing along and hit a crossing cow or a tractor, and in response engineers may have been forced to put up a sign. The question is: Would that person have done that regardless of the sign? The bulk of evidence is that people don’t change their behavior in the presence of such signs. Children playing, School zone? People speed through those warnings, faster than they even thought, if you query them later. To take another example, the majority of people killed at railroad crossings in the U.S. are killed at crossings where the gates are down. If this is insufficient warning that they should not cross the tracks then is a sign warning that a train might be coming really going to change behavior? At what point do people need to rely on their own judgment? We as humans seem to act on the message that traffic signs give us in complex ways — studies have shown, for example, that people drive faster around curved roads that are marked with signs telling them the road is curved. We tend to behave more cautiously in the face of uncertainty."

  • Mar 1, 2011 at 6:31 pm

    Your comment about people driving around corners caused something to pop into my mind… It might just be me, but I find it very curious to observe when many motorists actually decide to pass a cyclist. Frequently, I'll sense a car coming up behind me, they'll hang for a bit, and then just as another car is coming from the other direction or the two of us are approaching a curve, they decide to pass. What's up with that? I have yet to figure out what causes people to slow down, hang tight for a moment and then choose a much more inappropriate time to pass. I'd love to know what's going through people's minds when they do this.

  • Victor Martelle
    Mar 2, 2011 at 4:16 am

    Whats going through their mind? "Oh my fucking god, this guy is going so damn slow wow im going to pass this idiot."

    Could be just me, but its usually dangerous to pass a cyclist on the commute I take, and they always pass me and put them selfs and myself in danger.

  • Alex Taylor
    Mar 2, 2011 at 4:58 am


    I think that the behavior you’re describing is actually a panic reaction to an impending reduction in choice. They are freaked out by the idea that they are potentially goin to be forced to hang out there indefinitely. “Oh man, here comes opposing traffic (curve), I’d better go now!”

    So maybe related to the thesis of the article!

  • Labann
    Mar 2, 2011 at 5:42 am

    Don't have to go far to see what traffic controls are all about. Cranston's conservative mayor stuck hundreds of new STOP signs around city defying ordinance that says council has to approve. Motivated to raise revenue, they remained for years before council finally acquiesced at cost to remove them. But police don't enforce. I watch scores of motorists going through the STOP sign outside my office all day. So, in essence, they just waste tax revenue when installed, then afterwards, gasoline, road repair, and vehicle maintenance.

    "Boulevard stop" is already a law, but few motorists even understand what it means, that is, you have to stop before crossing or merging into traffic on a thoroughfare (avenue, boulevard, or highway) from a secondary street, but not controlled highway with merging lanes. Just common sense to stop when you're not sure what to do.

  • Mar 2, 2011 at 7:15 am

    As an aside, the highway mentioned in Korea was the Cheonggye Freeway, named after the river it was built over. The highway was removed and the river restored. A delegation from Korea came to Providence to see what we did at Waterplace when they were planning their river restoration.

    More Info

  • Mar 2, 2011 at 7:24 am

    @Jef thanks for the pointer to that article, it's an even greater story now that we have a connection! Looking through the pictures in the article, what a great change for Seoul. What was once a concrete jungle now looks like a vibrant place for people.

  • Mar 2, 2011 at 7:29 am

    @Alex interesting guess. What really puzzles me, and perhaps I didn't make clear in my initial description, is that these people who ultimately choose to pass at a dangerous time often hesitate through times when it would have been perfectly safe to pass. I guess the thought process could go something like:

    Hmm… cycliss ahead I better slow down, because I don't know what to do

    Crap… there is an opposing car/curve ahead, I better go now so I don't get stuck behind this cyclist

    So even though they already slowed down and their travel time was impacted, they choose to push through when it's unsafe for the cyclist and themselves. I just don't get it.

  • Mar 2, 2011 at 9:42 am

    Similarly to

    “Oh man, here comes opposing traffic (curve), I’d better go now!”

    I have observed

    "Oh man, it is snowing and getting slippery. I'd better speed up now to get home before it gets worse!"

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  • Dennis
    Mar 2, 2011 at 2:38 pm

    I think that the though process might be similar to the "Stop Sign" behavior. Drivers recognize that they are required to to take an action (not run the cyclist over or stop at the stop sign), then they are free to continue. Have you seen someone pull up to a stop sign then pull out into traffic? After all, they did the right thing initially, right?

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