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Math Says You're Driving Wrong and It's Slowing Us All Down (wired.com)
A new study in IEEE Transactions on Intelligent Transportation Systems mathematically suggests that if you and everyone else on the road kept an equal distance between the cars ahead and behind, traffic would move twice as quickly. From a report: Now sure, you're probably not going to convince everyone on the road to do that. Still, the finding could be a simple yet powerful way to optimize semi-autonomous cars long before the fully self-driving car of tomorrow arrives. Traffic is perhaps the world's most infuriating example of what's known as an emergent property. Meaning, lots of individual things forming together to create something more complex. Emergent properties are usually quite astounding. You've probably seen video of starlings forming a murmuration, a great shifting blob of thousands upon thousands of birds. Bats flying en masse out of a cave is another example, swarming sometimes by the millions through a small exit. And scientists are just beginning to understand how they do so.
if you and everyone else on the road kept an equal distance between the cars ahead and behind, traffic would move twice as quickly.
Yes, because no one would be merging into traffic anymore.
If everyone kept an equal distance and followed a standard merging pattern of every other car, then it would likely solve the merging problem as well. Long ago we were shuffling decks of cards in a much less practical and inefficient way until certain physical moves were found to increase that efficiency ten-fold.
It's also well-known that impatience creates stop-and-go traffic patterns, which is but one of the many human factors that autonomous solutions will be looking to solve.
Common sense says we don't need math to show what is slowing down traffic. Maintaining distance really means matching speed, acceleration, and deceleration. If those happen distance itself becomes less of a key factor. Added distance is just an aid for drivers who aren't good at staying with traffic flow.
If you want traffic improvement,
1) get left lane laggards to drive properly and not slow down faster traffic
2) get everyone to be expeditious when intersection lights turn green
3) teach people not to contribute to traffic compression waves by over decelerating and then under accelerating
That's not surprising. Spread cars out too much and you reduce the roadway's capacity. Put them too close together and you have to slow down to accommodate the driver's minimal reaction time. Having every driver choose his own distance means you can have both effects simultaneously: wasted space and insufficient response time.
Put all these constraints on and it seems obvious that you want to space cars uniformly with the minimal distance consistent with whatever statistical level of safety you demand. Naturally robotic systems will be more efficient since they require less response time -- in fact they can react to events that will cause the car in front to slow.
What would be interesting is to see the exact results they came up with: how far for how fast and under what conditions? What are the significant input parameters of the model? For example I'm sure varying the acceptable probability of a crash has a powerful effect on the optimal distance.
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Don't drive closer to the car in front of you than security dictates, even if there is a tailgater behind you.
You should do exactly the opposite. If someone tailgates you, leave more distance in front of you so you can afford to brake slowly, giving the person behind you more warning time.
Just set your Tesla (or other modern) adaptive cruise control to, say, five car lengths, and just steer. It is far far easier than having to brake/accelerate and the hardware watches even when the driver has zoned out. No worries about hitting the idiot in front. No worries if someone merges into your lane: the car adapts.
And a slight speed adjustment allows the distance to return to normal after the merge
The problem is that a road runs at maximum capacity when speed is high and distance is minimal. A slight speed adjustment, like you suggested, has the effect of decreasing maximum road capacity.
That means that the road after the merge point not only has to deal with more cars, but also with a lower capacity to carry those cars. This lower capacity will propagate backwards to the road before the merge point. And that's how you end up with a traffic jam.
Which also takes us into arguments of age and experience. The youngest drivers usually have the best reaction time but may not necessarily make the best choices prior to needing to use that reaction time. The oldest drivers have the most experience with what traffic conditions are to be like but may have very poor reaction times. The sweet-spot is kind of hard to calculate but probably biases toward a youngish driver that has figured out traffic conditions but still has fast reaction times.
When I read the article summary it sounds like they want our cars to operate like trains, which all maintain the same distance (on account of mechanical coupling) and all go the exact same speed (again, mechanical coupling). Trouble is, with cars everyone has different destinations and therefore won't maintain the same speed. Cars slow to turn-off. Cars must enter the right-of-way. Not all drivers are driving for the same reason either, some enjoy driving performance vehicles, using that quick acceleration to get up to speed whenever they can, while others drive much more gently.
The argument for us all driving an exactly particular way rings of the spherical cows in a vacuum solution to a farming problem. Isn't going to work in real-world applications.
Do not look into laser with remaining eye.
The sweet spot is well known - it's around 50-60. That's why insurance companies offer people in that age bracket the lowest rates - they have the fewest accidents.
I work in a manufacturing environment, and changing even a handful of people's behavior is so incredibly difficult and costly ("always pick up one orange nut at a time, then the blue nut, don't grab two at once.") that asking everyone to change the way they drive is just ridiculous. You have to change things so that the desired behavior is the easier behavior. For instance, advanced cruise control that adjusts your distance automatically might be a solution. In our plant, if the process says they should do X before Y, then the only way to ensure it actually happens all the time is to prevent Y from happening until there's proof X happened. People just aren't reliable.
"I have never let my schooling interfere with my education." - Mark Twain