Countdown to red vs. countdown to green: Building a better traffic light

February 28, 2010 in Blog posts | 20 comments

Rory Sutherland wonders about the virtues of traffic lights that tell drivers how many seconds until a green light turns red, or how many seconds until a red light turns green. They appear to be quite popular in China and Taiwan where according to a Freakonomics reader the green lights that count down to red lights increase accidents at intersections, while the red lights that count down to green lights cut them in half. Essentially, moving drivers try to rush through the intersection, while stopped drivers show more patience before speeding out into it. The photo below, from Chinese expat Stephen Cronin, is an example of the red lights that count down to a green.

Rory dug up a bit more information about the lights and it seems they are mainly manufactured by Chinese companies, including Shenzhen Yuhong Electronics and Hepol Electric Enterprises. This likely explains why the Chinese have been the earliest and most widespread adopter of the lights, although they can be found on most continents by now. The best red light countdown design does not come from a Chinese engineer, but instead a Serbian, Damjan Stanković, creator of the Eko, a red light whose outer edge turns from red to black, shrinking the red circle until it turns to green.

“When you think about it, you don’t need this information counted in seconds, you just need to see the speed of the progress bar to give you an estimate of the time,” Stanković told the Daily Mail. Humans have an intuitive sense of numbers, even when they aren’t looking at them.

Addendum: Counting down to walk would be a good idea for pedestrians too.

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  • cooketristan

    There is debate in the human factors community if this is a good thing for behaviour. They have had the same thing with green lights in the past. The result – if I rememebr right -was people flooring when the green was counting down and more cars running red lights.

    Basically, the old risk compensation argument.

  • misterxroboto

    i think cooketristan has an excellent point. we may be able to benefit from this by using only the red light countdown, without seeing people trying to floor their way through the intersection.

    the biggest counterargument i can think of is familiarity. if i know that running the light will prevent making me wait 90 seconds for a light? i might be inclined to run. if it's going to make me wait 15 seconds? i might be inclined to wait.

  • Martin Henner

    I think Ashland, Oregon has pedestrian walk signs that count down.

  • Anonymous

    There is debate in the human factors community if this is a good thing for behaviour. They have had the same thing with green lights in the past. The result – if I rememebr right -was people flooring when the green was counting down and more cars running red lights.

    Basically, the old risk compensation argument.

    • Anonymous

      i think cooketristan has an excellent point. we may be able to benefit from this by using only the red light countdown, without seeing people trying to floor their way through the intersection.

      the biggest counterargument i can think of is familiarity. if i know that running the light will prevent making me wait 90 seconds for a light? i might be inclined to run. if it’s going to make me wait 15 seconds? i might be inclined to wait.

      • http://www.nudges.org/ Nudge blog

        Isn’t this an interesting asymmetry? You might think of it as a version of the status quo bias. If I’m in motion, I want to keep moving. If I’m stopped, I don’t mind staying still.

    • Andrew

      I think you’re repeating the sentiment of the article. Green lights that count down to red, showing how long is left before you must stop, tend to cause anxiety and accidents. Red lights that count down to green, showing how long you must wait before you go, lend themselves to increased patience and half the accidents.

      • Anonymous

        No quite… There is never an always in these situatons. What you say is possible but I would like to see proven.

        misterxroboto I think has it more down. It’s possible that the knowledge of light time could effect driver behaviour in the negative over time. FOr example, on your regular route you are more acutely aware of the time red lights take (rather than sitting back and listening to NPR or something, not really thinking about the light until it goes green). You might then (over time) tend to speed towards green lights you know take ages to change if you miss them.

        I cannot prove either of the above. But I remain unconvinced that having the extra infomation of time actually helps. In human factors language it jumps from ‘skill’ or ‘rule’ based behaviour to ‘knowledge’ based behaiour.

        It will change the way people act, but not as a unit. Some will change differently to others, and the effect will vary from situation to situations.

        I remain onconvinced (but willin to BE convinced) that knowing anything other that ‘stop’ is useful out of a red light.

  • Martin Henner

    I think Ashland, Oregon has pedestrian walk signs that count down.

  • modalshift

    Copenhagen has countdown timers for pedestrians – and for cyclists. I've also come across them in plenty of other places in northern Europe and Scandinavia.

  • Anonymous

    Copenhagen has countdown timers for pedestrians – and for cyclists. I’ve also come across them in plenty of other places in northern Europe and Scandinavia.

  • http://www.nudges.org/ Nudge blog

    Isn't this an interesting asymmetry? You might think of it as a version of the status quo bias. If I'm in motion, I want to keep moving. If I'm stopped, I don't mind staying still.

  • http://twitter.com/iamdaggie Christopher Daggett

    Here's a video on youtube of a light that counts down to green and red: http://www.youtube.com/watch?v=f7dZj0n0LOw

  • http://twitter.com/iamdaggie Christopher Daggett

    Here’s a video on youtube of a light that counts down to green and red: http://www.youtube.com/watch?v=f7dZj0n0LOw

  • Andrew

    I think you're repeating the sentiment of the article. Green lights that count down to red, showing how long is left before you must stop, tend to cause anxiety and accidents. Red lights that count down to green, showing how long you must wait before you go, lend themselves to increased patience and half the accidents.

  • cooketristan

    No quite… There is never an always in these situatons. What you say is possible but I would like to see proven.

    misterxroboto I think has it more down. It's possible that the knowledge of light time could effect driver behaviour in the negative over time. FOr example, on your regular route you are more acutely aware of the time red lights take (rather than sitting back and listening to NPR or something, not really thinking about the light until it goes green). You might then (over time) tend to speed towards green lights you know take ages to change if you miss them.

    I cannot prove either of the above. But I remain unconvinced that having the extra infomation of time actually helps. In human factors language it jumps from 'skill' or 'rule' based behaviour to 'knowledge' based behaiour.

    It will change the way people act, but not as a unit. Some will change differently to others, and the effect will vary from situation to situations.

    I remain onconvinced (but willin to BE convinced) that knowing anything other that 'stop' is useful out of a red light.

  • cdhutch

    One idea I've had would be to paint solid lane-dividing lines leading up to intersections for a length that is a function of the yellow light time and the speed limit. Properly designed, if a car has reached the solid line area, its driver knows that it can safely clear the intersection if traveling at the speed limit.
    I haven't worked through the second order effects and nudges

  • cdhutch

    One idea I’ve had would be to paint solid lane-dividing lines leading up to intersections for a length that is a function of the yellow light time and the speed limit. Properly designed, if a car has reached the solid line area, its driver knows that it can safely clear the intersection if traveling at the speed limit. nI haven’t worked through the second order effects and nudges

  • cdhutch

    One idea I’ve had would be to paint solid lane-dividing lines leading up to intersections for a length that is a function of the yellow light time and the speed limit. Properly designed, if a car has reached the solid line area, its driver knows that it can safely clear the intersection if traveling at the speed limit.
    I haven’t worked through the second order effects and nudges

  • http://www.aom.sg air purifier

    the virtues of traffic lights that tell drivers how many seconds until a green light turns red, or how many seconds until a red light turns green. — very clever question..