4 ms·

An interesting question, but I must ask — why is the answer important?

larrydag 15y ago
I could see this being possibly useful in traffic "wave" disruption. I've read on the traffic wave theory before and there has been some ideas that if the wave could be disrupted long enough to clear out that it would dissolve and traffic would start to flow again at its normal pace. I suppose that disruption could be done by police cars allowing buffers to build thus disrupting the wave. Can you tell I find this field fascinating? Full disclosure I have a degree in Operations Research.
- mattmanser 15y ago
  Sans the copper, they do this over here in the UK by using variable speed limits, hard shoulder 'opening' and the real threat of speed cameras. Seems to work in my albeit anecdotal and very occasional experience of driving near Birmingham in rush hour. Would be interested to hear the perspective on UK HNers who were aorund before/after they implemented this. And they're using it more and more: http://www.bbc.co.uk/news/uk-england-13426799 http://www.bbc.co.uk/news/uk-england-13426799
  - pbhjpbhj 15y ago
    I must say I've long assumed that they also used police cars for flow control - now of course they have the Highways Agency vehicles¹ which look so much like police cars as to cause the same slowing to <70mph from what's often an average in the outer lanes of 85. --- ¹ -- I can't see how the Highways Agency are not running fowl of the law against "impersonating a police officer" by the livery of their vehicles.
    - larrydag 15y ago
      Notice how truckers work with highway congestion too. They tend to slow down to allow congestion in front of them to flow. This might look at first to allow braking space for the big trucks but I think it has a lot to do with the traffic flow as well.
      - sumbry 15y ago
        Truckers don't like to change gears. It's much more efficient for them to stay in a lower gear and coast at a consistent speed than it is to constantly change gears and brake.
- politician 15y ago
  One of those papers mentioned in the article described "negative traffic" as the gaps in an otherwise saturated segment of road. Vehicles travelling behind the gap tended to have smoother acceleration curves. I've used this idea to great effect when stuck in traffic by moving into the far left lane, building up a nice gap in front of me, and then cruising at a steady 2-3mph instead of stop-and-go. I've noticed that people generally recognize this as a net-positive and will "follow the leader" with only one or two cheaters (cars which pass me and move into the gap) -- usually the cars immediately behind me. In order to pull this off, the lane leader needs to maintain a variable length buffer of gap-space in order to prevent their velocity from falling to zero ("stopping"). As the traffic density drops, the gap increases, and you can speed up which ups the average velocity of all of the cars in the lane. Eventually, traffic density will drop down to "normal" conditions at which point cars begin to cheat with increasing frequency until a normal traffic equilibrium is reached (e.g. "not in traffic"). I would love to see an interactive model of this strategy, specifically to figure out the optimum number of lane leaders; less than the total number of lanes, I suspect.
  - chadgeidel 15y ago
    I myself try to do that in my lane. Building up a gap so I don't have to use the clutch and can just idle through traffic. I've had varying success with this technique.
    - larrydag 15y ago
      One of my pet peeves is seeing other drivers tailgate. My hypothesis is that all congested would be alleviated if everyone followed the 2 second rule.
  - TheHegemon 15y ago
    I try to do that as well but it's hard to built up a big enough gap especially in LA where a 'stop' can last up to 15+ seconds. Trying to make a gap big enough without seeming like a complete douche is hard and it makes it that much harder that I have been conditioned to speed up as much as possible.
  - 15y ago
MrMan 15y ago
One reason might be that if you can reduce the effects of traffic you can make our economy more efficient and improve civic life. Also, the theory that is used to model the behavioral aspects of traffic flow could very well apply to other areas of the social sciences. So a researcher trying to solve a different problems might read this problem and be able to apply the model to his own area of research.
pitt1980 15y ago
lots of manhours are lost in traffic http://www.foreignpolicy.com/articles/2010/08/24/the_world_s_worst_traffic?page=0,4 http://www.foreignpolicy.com/articles/2010/08/24/the_world_s... I would say understanding the dynamics of it is a perfectly important question for a PhD thesis

I could see this being possibly useful in traffic "wave" disruption. I've read on the traffic wave theory before and there has been some ideas that if the wave could be disrupted long enough to clear out that it would dissolve and traffic would start to flow again at its normal pace. I suppose that disruption could be done by police cars allowing buffers to build thus disrupting the wave. Can you tell I find this field fascinating? Full disclosure I have a degree in Operations Research.

mattmanser 15y ago
Sans the copper, they do this over here in the UK by using variable speed limits, hard shoulder 'opening' and the real threat of speed cameras. Seems to work in my albeit anecdotal and very occasional experience of driving near Birmingham in rush hour. Would be interested to hear the perspective on UK HNers who were aorund before/after they implemented this. And they're using it more and more: http://www.bbc.co.uk/news/uk-england-13426799 http://www.bbc.co.uk/news/uk-england-13426799
- pbhjpbhj 15y ago
  I must say I've long assumed that they also used police cars for flow control - now of course they have the Highways Agency vehicles¹ which look so much like police cars as to cause the same slowing to <70mph from what's often an average in the outer lanes of 85. --- ¹ -- I can't see how the Highways Agency are not running fowl of the law against "impersonating a police officer" by the livery of their vehicles.
  - larrydag 15y ago
    Notice how truckers work with highway congestion too. They tend to slow down to allow congestion in front of them to flow. This might look at first to allow braking space for the big trucks but I think it has a lot to do with the traffic flow as well.
    - sumbry 15y ago
      Truckers don't like to change gears. It's much more efficient for them to stay in a lower gear and coast at a consistent speed than it is to constantly change gears and brake.
politician 15y ago
One of those papers mentioned in the article described "negative traffic" as the gaps in an otherwise saturated segment of road. Vehicles travelling behind the gap tended to have smoother acceleration curves. I've used this idea to great effect when stuck in traffic by moving into the far left lane, building up a nice gap in front of me, and then cruising at a steady 2-3mph instead of stop-and-go. I've noticed that people generally recognize this as a net-positive and will "follow the leader" with only one or two cheaters (cars which pass me and move into the gap) -- usually the cars immediately behind me. In order to pull this off, the lane leader needs to maintain a variable length buffer of gap-space in order to prevent their velocity from falling to zero ("stopping"). As the traffic density drops, the gap increases, and you can speed up which ups the average velocity of all of the cars in the lane. Eventually, traffic density will drop down to "normal" conditions at which point cars begin to cheat with increasing frequency until a normal traffic equilibrium is reached (e.g. "not in traffic"). I would love to see an interactive model of this strategy, specifically to figure out the optimum number of lane leaders; less than the total number of lanes, I suspect.
- chadgeidel 15y ago
  I myself try to do that in my lane. Building up a gap so I don't have to use the clutch and can just idle through traffic. I've had varying success with this technique.
  - larrydag 15y ago
    One of my pet peeves is seeing other drivers tailgate. My hypothesis is that all congested would be alleviated if everyone followed the 2 second rule.
- TheHegemon 15y ago
  I try to do that as well but it's hard to built up a big enough gap especially in LA where a 'stop' can last up to 15+ seconds. Trying to make a gap big enough without seeming like a complete douche is hard and it makes it that much harder that I have been conditioned to speed up as much as possible.
- 15y ago

MrMan 15y ago

One reason might be that if you can reduce the effects of traffic you can make our economy more efficient and improve civic life. Also, the theory that is used to model the behavioral aspects of traffic flow could very well apply to other areas of the social sciences. So a researcher trying to solve a different problems might read this problem and be able to apply the model to his own area of research.

pitt1980 15y ago

lots of manhours are lost in traffic http://www.foreignpolicy.com/articles/2010/08/24/the_world_s_worst_traffic?page=0,4 http://www.foreignpolicy.com/articles/2010/08/24/the_world_s... I would say understanding the dynamics of it is a perfectly important question for a PhD thesis