Looking to bounce something off you guys.
Ever wondered why you sit in a traffic jam on a motorway for 30mins, then get to the end of the jam, only to see no apparent reason for it?
Well, there is a reason, and the mathematical term is “queue theory”, which I’m not going to detail, but I am going to try to summarise it's implications as simply as possible.
So, here’s the beans:
Imagine a queue of traffic in single lane, all travelling at exactly 70mph. In theory, and assuming ALL cars maintain exactly that speed, they could drive nose to tail with just cm between them. Clearly in many ways, that would be a good thing, for one thing the aerodynamic benefits.
However, we don’t live in a perfect world, and there’s a mass of factors that influence the actual speed of a car, even when it’s trying to maintain 70mph, e.g. driver letting his foot off the throttle, going up an incline, down a hill etc. As such, there will always been minor volatility in the speed of a car, even one trying to maintain a certain speed.
The question then is just how close the vehicles are behind. If we take a scenario of cars running very close together, a speed reduction of a leading vehicle by say 3mph, will result in the car behind to slow not by 3mph, but by probably more. That in turn will pass down the line, potentially to the point where a car 20 vehicles back may end up stopped completely (ah the joys of mathematics). Seen from above, it’s the concertina effect.
The answer is frankly, utterly obvious, don’t maintain “braking distance” or less, maintain a “queue distance”, that no only achieves appropriate braking distance, but includes sufficient space to allow a degree of modulation of speed, without significantly impacting upon the vehicles behind you.
At this point, I’m conscious of how many drivers are going to say, “yeah, but when I do that, people cut in front of me”.
My answer is simple, some will, but nothing like as many as you think or claim. I now normally drive with “queue distances” (QD) and watch how the majority of drivers around me drive around as utter lemmings, far too many nose to tail, and less because they know why, mostly because everyone else does it. Sure, I get the odd driver cut into my QD, but it’s not that often, and typically, they’re the ones insistent on weaving in and out of traffic, and often vacate the space in-front of me within a mile anyway, meaning that it’s not a big deal. More to the point, said “weaver” is going to do it, almost regardless of whether I facilitate him, or drive nose to tail to try to stop him. The only difference being how dangerous is his weaving going to be.
Another example are the drivers who wait until the last few metres before pulling into the queue for the “exit lane” on a motorway.
Now don’t get me wrong, these people drive me nuts too, as I consider it highly impolite for them to think that they’re more important than the rest of us, but again, you are NOT going to stop them by driving nose to tail. They’ll still push into the queue. More to the point, by trying to stop them, they end up stopped in the lane they’re currently in, which backs up all the vehicles in that lane driving normally, and in itself causes a jam.
In short:
Anyone think that this should be in the highway code?
Ever wondered why you sit in a traffic jam on a motorway for 30mins, then get to the end of the jam, only to see no apparent reason for it?
Well, there is a reason, and the mathematical term is “queue theory”, which I’m not going to detail, but I am going to try to summarise it's implications as simply as possible.
So, here’s the beans:
Imagine a queue of traffic in single lane, all travelling at exactly 70mph. In theory, and assuming ALL cars maintain exactly that speed, they could drive nose to tail with just cm between them. Clearly in many ways, that would be a good thing, for one thing the aerodynamic benefits.
However, we don’t live in a perfect world, and there’s a mass of factors that influence the actual speed of a car, even when it’s trying to maintain 70mph, e.g. driver letting his foot off the throttle, going up an incline, down a hill etc. As such, there will always been minor volatility in the speed of a car, even one trying to maintain a certain speed.
The question then is just how close the vehicles are behind. If we take a scenario of cars running very close together, a speed reduction of a leading vehicle by say 3mph, will result in the car behind to slow not by 3mph, but by probably more. That in turn will pass down the line, potentially to the point where a car 20 vehicles back may end up stopped completely (ah the joys of mathematics). Seen from above, it’s the concertina effect.
The answer is frankly, utterly obvious, don’t maintain “braking distance” or less, maintain a “queue distance”, that no only achieves appropriate braking distance, but includes sufficient space to allow a degree of modulation of speed, without significantly impacting upon the vehicles behind you.
At this point, I’m conscious of how many drivers are going to say, “yeah, but when I do that, people cut in front of me”.
My answer is simple, some will, but nothing like as many as you think or claim. I now normally drive with “queue distances” (QD) and watch how the majority of drivers around me drive around as utter lemmings, far too many nose to tail, and less because they know why, mostly because everyone else does it. Sure, I get the odd driver cut into my QD, but it’s not that often, and typically, they’re the ones insistent on weaving in and out of traffic, and often vacate the space in-front of me within a mile anyway, meaning that it’s not a big deal. More to the point, said “weaver” is going to do it, almost regardless of whether I facilitate him, or drive nose to tail to try to stop him. The only difference being how dangerous is his weaving going to be.
Another example are the drivers who wait until the last few metres before pulling into the queue for the “exit lane” on a motorway.
Now don’t get me wrong, these people drive me nuts too, as I consider it highly impolite for them to think that they’re more important than the rest of us, but again, you are NOT going to stop them by driving nose to tail. They’ll still push into the queue. More to the point, by trying to stop them, they end up stopped in the lane they’re currently in, which backs up all the vehicles in that lane driving normally, and in itself causes a jam.
In short:
- Use “queue distances”
- BE POLITE to your fellow drivers. Make distance and allow other vehicles space
- Don’t feel it’s appropriate to try to retaliate or “police” them. It’s NOT your job, and more importantly, they are NOT the people causing the jam. YOU are by having no queue distance, though they certainly don’t get off for free as they are the catalyst to the issue
Anyone think that this should be in the highway code?
