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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.
I was trying to get from the Domestic to the International terminal, about 5km, in a cab (along with wife and luggage). The lightrail system was under construction, which added to the mess. Traffic was gridlocked until about midnight, when it started moving. Turns out there was one traffic light that caused the gridlock. Once that went to flashing yellow, the drivers negotiated their way through the intersection.
Math says you're treating Slashdot readers wrong and it's making the internet worse for all of us.
than getting stuck behind a driver that keeps racing up to the car in front of them and then hitting the brakes, falling back and doing it all over again. Keep it steady man.
In the coming years, there will no doubt be 1-2 lanes on federal highways just for automated driving. Ideally, it will have variable speeds all the way up to 100 on good days. Keep in mind that federal highways were designed for 120 mph minimum.
I prefer the "u" in honour as it seems to be missing these days.
California drivers (I grew up in Orange County) once had the zipper merge perfected. Today they seem to have abandoned all discipline.
When I drive bumper to bumper in traffic ( equal distance between the cars ahead and behind) I move at a crawling speed; If people increased that space we would move twice as slow? I did not think that was possible.
Oh, my, some student has handed in his "study" and it made the papers. The next study that debunks it, probably won't so everyone will keep believing this one. Like that old "study" that said 80 km/h was the ideal speed for max throughput (it's not).
They probably did a simulation where all cars were following the same algorithm. Which only works if, you guessed it, all cars are using the same algorithm. Otherwise, only a huge mess results.
I can see so many things wrong with this. For starters, if I understood correctly, when somebody tailgates me, I should tailgate the car in front of me as well so we keep an equal distance? Great way to cause pile-ups when one car starts to brake. (Been in one of those myself, I could stop just in time, so could the car behind me, but the three cars further back slammed us all together, fortunately there was a dashcam).
So we're back to a minimum safe distance between me and the car in front, which is what I normally do. Now, if the car behind me is further back, according to the "study", I should slow down to increase my distance in front and reduce my distance behind. But then of course the car behind me is going to slow again to get back to its old distance, so I keep slowing until I have as much distance in front of me as the car behind me. Now the car in front of me is going to slow down to as well, because he wants as much distance in front of him as behind him. I don't exactly see throughput improving here...
Max throughput is achieved if cars simply keep the shortest safe distance, allowing for small fluctuations in distance to keep speed as constant as possible. And yes, indeed, very few drivers actually do that.
This video is nine years old and shows something similar, and the flow concept underlying it has been discussed for decades ... https://www.youtube.com/watch?...
There, solved it.
The leader is an impatient/enraged/drunken/drugged/distracted human, incapable of removing those traits that have tainted damn near every mode of transportation ever invented, which is why we're now looking for an autonomous leader.
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.
Post may contain irony: discontinue use if experiencing mood swings, nausea or elevated blood pressure.
... because obviously, if maximizing the efficiency of human work in terms of how many products/services are created is the defined goal, it makes absolutely no sense to have a multitude of competing companies spend lots of effort and material into developing/producing/advertising the same kind of product/service.
The only catch to this, just as with human car drivers: Not compatible with homo sapiens, which evolution shaped over millions of years to behave competetive and give a shit about some "greater good" for mandkind as a whole.
Once we have car to car communication. This type of driving would be possible.
That doesn't imply it would be desirable. Cars are not only for transportation from A to B.
The day I can't go on a joyride anymore, I won't be using a self-driven queue-communicating cart; I will be using public transportation.
... speed limits.
Artificially low speed limits.
"Not to mention all the idiots who use words like boxen."
Anonymous Coward on Monday August 04, @06:49PM
Seriously? It takes the IEEE to tell us of something which has been known since before "The Godfather" hit the screens??
And what of variable reaction times and inertial vectors?
If everyone is accelerating when the car behind them gets closer all it takes is one tailgating asshole to produce a multiple car collision hasard of cars driving too close together.
Don't drive closer to the car in front of you than security dictates, even if there is a tailgater behind you.
Democracy is a sheep and two wolves deciding what to have for lunch. Freedom is a well armed sheep contesting the issue
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.
Never drink and derive.
Isn't that what NASCAR is anyway? Between the wrecks and such,...
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.
In the UK, the M25 (circular road around London) has a variable speed limit.
As traffic becomes heavier, the speed limit drops. But all lanes get the same speed limit. The limit is heavily enforced with cameras.
With the limit set quite low, the traffic proceeds much more uniformly, there is no advantage to changing lanes, everyone drives at the limit.
The result is that more cars can flow past any point on the road. It's another example of the effect predicted by the paper.
The real "Libtards" are the Libertarians!
Nobody who drives *EVER* tries to monitor the distance between their car and the one BEHIND them! It's your responsibility to monitor the distance to the car in front of you. This is why all the seats in an automobile face FORWARD. Duh!
That will help solve the traffic problem too.
If you want to fix traffic in densly populated areas, you should avoid cars and use mass transit. Light rail, trams and modern busses can achieve higher travel speeds and higher throughput than cars. To connect less populated areas, you use park and ride systems, i.e. , parking lots with direct bus/tram/train access.
It's just the idiots around me that are doing it wrong!
> you're probably not going to convince everyone on the road to do that
We'll do that when cars are driven automatically and AI does that, automatically.
Slashdot, fix the reply notifications... You won't get away with it...
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.
Math Says You're Driving Wrong and It's Slowing Us All Down
Fuck you and your condescending clickbait headlines. You don't know what I'm doing.
if you and everyone else on the road kept an equal distance between the cars ahead and behind, traffic would move twice as quickly. Now sure, you're probably not going to convince everyone on the road to do that.
Damn right you're not, because it's a fucking stupid idea. You want drivers to monitor the distance to the car behind them? There are enough problems getting drivers to concentrate on the direction they're travelling in.
systemd is Roko's Basilisk.
Physics says: Information transmission is not instantaneous.
Corollary: it is impossible to keep equal distances.
When the guy in front of you decelerates, you necessarily decelerate after him because Information transmission is not instantaneous. This implies the distance between you end him is reduced. Similarly, acceleration increases distances. QED.
Master of the obvious. Armies have known this for millennia. That's why soldiers maintain fixed distance and all start out together with a "forward...march" command and stop with a "company...halt". Try that at the next traffic light when you are 5 cars back. Man, if everyone just all went at the same time when the light turned green it would be awesome, but without an automated system it's just a 4 car pile-up.
With human drivers you inevitably get the "slinky" effect due to reaction time and differences in preferred speed and follow distance.
I believe this will eventually become the force driving the adoption of self-driving technology. When we get to the point autonomous cars do it right and are mixed in with human-driven cars that are screwing up and slowing down the traffic pattern for everyone else. I can see the current driving model being totally turned on its head with commuters eventually demanding that we ban human drivers.
There will also be economic pressure. Human drivers need signs, lights, and a weighty infrastructure investment. Autonomous cars need none of that expensive support.
That's our life, the big wheel of shit. - The Fat Man, Blue Tango Salvage
The way TFA it explains it is pretty silly. Keeping the same distance to the car behind you just means the car behind you is keeping the same distance from you as you are from the car in front of you. i.e. the cars are all equally spaced. Things like one car tapping its brakes, failing to maintain speed, or merging into the lane causes the cars behind it to slow down. If the cars behind this one car are bunched up, it exacerbates the slowdown. The optimal way to space the cars to minimize this slowdown (without knowing ahead of time which car will slow or merge) is to equally space all of them. Simple as that. (If the slowdown happens when the cars aren't bunched up the impact is smaller than when equally spaced. But on balance the bunched up slowdown outweighs the non-bunched slowdown. Like swimming upstream then downstream back to your start point at a constant speed relative to the water is slower than swimming the same distance when there's no current, because with a current the slowdown on the upstream leg exceeds the speedup on the downstream leg.)
The capacity of a road is how many cars can pass a fixed point per hour. You can increase this by widening the roads, but that involves a lot of eminent domain and construction work. The alternative is to increase the speed of the cars. Double the speed and you double the number of cars that pass a fixed point per hour.
Except we have a safety rule which says to keep a 2 second gap between you and the car in front of you (because braking distance increases with speed while human reaction time remains constant) . When there's a lot of traffic, that rule effectively cancels out the flowrate benefit of speeding up. Twice the speed, twice the gap, same number of cars pass a fixed point per hour. That's why traffic engineers have been so interested in autonomous cars, adaptive cruise control, and automatic braking systems. If you can increase the speed without increasing the distance (shrink the gap to significantly less than 2 seconds), you increase the capacity of the road and thus increase its ability to handle more traffic. As for problems merging when the gaps between cars is smaller, it's been proposed that cars on the highway form a train - a block of a dozen or so cars on cruise control radar-locked bumper to bumper - with larger spaces in front of and behind the train where new cars can merge into.
Of course, my response is if the optimal solution is a train, then just use a train. Create railroad cars which automobiles can drive onto, which depart at regular intervals between common distant destinations, like a roll-on roll-off ferry. People can stay in their cars during the trip. Watch TV, play games, enjoy the scenery, browse the web. And the car engines can be off during the trip so only the train locomotive needs to burn energy, which would put the fuel efficiency of the entire train at around 200 MPG (at 2 tons per vehicle).
What you are saying makes sense, but that's not what the study says. Read the summary again.
They say that in the article, itâ(TM)s meant for autonomous cars.
I love tailgaters. I always just let off the gas pedal, I refuse to speed or tailgate because some asshole doesn't know how to drive safely.
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.
You must live in an apartment above the starbucks you work in. I understand your kind now.
Well, they are just saying that rather than minimum distances, safe distances, or buffers on the prior, equal front-back distance is a better model for throughput. Not that it will prevent traffic jams. And it is meant for autonomous cars.
A centrally managed system would probably be better but an anonymous car will not be able to determine that on its own.
I was once in a traffic jam that had traffic backed up for miles. All the cars were equal distance apart, but none of them were moving! Turns out there was no accident ahead, no stalled cars, no reason whatsoever.
What happens is some idiot lightly taps his brakes, may to turn off his cruise control, who knows. Then the driver behind him, not knowing how hard the first one is braking, taps his brakes a bit more. This continues with drivers braking a little harder all the way back, so that cars a hundred yards back come to a complete stop. Of course, then all the traffic behind them comes to a stop. We've all seen it happen.
The answer is to never, ever touch your brakes on an interstate. If everybody paid attention and kept a decent distance apart, you'd never NEED to brake. Exits and on-ramps should be built such that all braking and slowing down would be done on them, not out in the travel lanes.
Brake lights cause traffic jams. If you're on a motorway (freeway), never use your brake pedal except in an emergency. That's what engine braking (or regenerative braking on modern cars) is for. Keeping a steady speed, and only accelerating and decelerating slowly helps other drivers to match speed when merging, it also does wonders for fuel economy.
This guy figured all that out in detail years ago ...
The biggest cause of congestion in recent times is the number of people looking down at their cellphone (pretending not to since in the UK it is illegal) in stop-start traffic. I watch these morons look up occasionally, notice the lights have changed, like 5 mins ago, and move off... The car behind then does the same thing, after eventually noticing and, oh, now the lights are red again. In the end, two, maybe three cars have made it through the junction when twice that many could have moved if people had been paying attention.
Says the guy that can't engrischen. You should use your native language, you might then look intelligent.
Oh, Alexander Peter Kowalski is American, and currently lives in upstate New York. He just appear to have some problems communicating rationally like most people. IANAMP, so I won't speculate on why, but I do think he needs help of a type we cannot offer here.
I still wish the owners here would adjust the lameness filter for AC posts to be a bit more strict, to avoid derailments like this. Too much use of bold, upper case, links to other slashdot posts and the trademark "P.S. =>" could easily be stopped, I think.
This is why I always pull into your lane when you try to pass me. You are screwing up the algorithm and I'm fixing it.
Some drink at the fountain of knowledge. Others just gargle.
If you have a road containing x lanes and a flow rate of y, then you can optimize traffic based on the predictive analysis of the population and when they *screeech* OMG WTF IS THAT ASSHOLE DOING! And then the traffic flow is zero. Q.E.D
~X~
Bad math. If you use oversimplified or wrong models, you will solve for bullshit.
That's why you have to explicitly state you assumptions, then go back over your solution checking them. e.g. sin(theta) = theta. Fine, no problem, theta better be small when all's said and done, or you've just wasted your time.
'Engineers' that don't use math, those are the ones to watch out for.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
You were doing it right, now your just another Bay Aryan.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
https://www.youtube.com/watch?...
In your environment, you may be able to, not in mine. I live in a large municipal area with over 12 million people and dense traffic. Leaving >2 times the usual inter-car distance in front of you is self defeating as other cars will just accelerate to cut in front of you& then brake to avoid running into the vehicle in front of him. You are again left with left with the usual inter-car distance or often less and a vehicle actively braking causing you to have to brake to re-establish it.
For me a tailgater is note someone just uncomfortably close but someone who is so close that he cannot avoid rear-ending me because he is so close that he cannot react fast enough even if I have to brake moderately.
As welshie noted, I agree that brake lights are often the initiating act of slowdowns/jams as those behind you often brake harder than you did & it is self-reinforcing. Using motor/regenerative braking is best.
Democracy is a sheep and two wolves deciding what to have for lunch. Freedom is a well armed sheep contesting the issue
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
If you're using your brakes to control your speed on the highway you're not a good driver.
>1) get left lane laggards to drive properly and not slow down faster traffic
With new legislation effective las October 1, the Nevada Highway Patrol is now issuing "obstruction of traffic" tickets to cars in the left lane that "know or reasonably should know" that their slow speed is obstructing traffic.
hawk
There, solved it.
The leader is an impatient/enraged/drunken/drugged/distracted human, incapable of removing those traits that have tainted damn near every mode of transportation ever invented, which is why we're now looking for an autonomous leader.
Correct. Sorry, but I have no intention of driving a hundred miles per hour just because some idiot that either believes they have the reflexes to stop their vehicle when its 2 feet behind the next car at that speed. Or doesn't give a damn. This is the automotive equivalent of the law of personal incredulity, where the stupidest person in the room wins.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
If birds and bats can do it, why can't we?
We don't have the evolved senses they do.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
Then only leave 1.5 times the distance. If you have the minimum safe distance in front, and the car in front of you slams on the brake, with someone else riding your tail, you'll end up in a collision.
If you can't leave enough space in front, because people end up cutting in, then move over and let the tailgater pass.
Keeping constant spacing and running at a reasonable speed within a lane may be good. But holding the same speed in adjacent same-direction lanes is very bad.
In driving classes, back in the mid-20th century, we were warned against it. You NEVER were to hold the same speed as a car in an adjacent lane. (About a 5 MPH drift, with leftward lanes faster, was close to ideal.) Judging by the behavior of current drivers on California freeways that lore has apparently been lost.
Some of the issues:
- Adjacent cars form a multi-lane "rolling roadblock". Drivers behind them who wish to travel faster are impeded, collect behind them, and end up "compressed", setting up the conditions for a chain, reaction multicar pileup.
- With an inter-lane drift a driver wishing to pass a slower car soon has an opening to switch lanes and proceed.
- With the slowest lane to the right and increasing speed to the left, merges and exits require less speed change and have better timing margins, long-distance traffic proceeds rapidly with little disturbance, and lane changes are easy. Drivers have the opportunity to rapidly distribute themselves among the lanes and drive at a speed where they're comfortable.
- When driving at the same speed as an adjacent vehicle you increase your risk of collision:
- If you're in a blind spot you STAY in the blind spot for a long time. The window of opportunity for the adjacent driver to happen to make a lane change into you - or into the space immediately in front of you, becomes much larger than if you had a relative drift.
- If you hold relative position the other driver's peripheral-vision motion detector doesn't keep him aware of your presence. After a minute or so you're likely to fall out of his attention. Then, if a sudden traffic situation makes him need to change lanes suddenly (or he just wants to change lanes and forgets to do a recheck), he may swerve into you.
(By the way: The two-way two-lane equivalent of the rolling road-block chain-reaction-collision precursor is the "rat pack", a term of art in traffic engineering. It occurs when the first driver goes slightly over the limit and the second driver won't pass because he doesn't want to risk the necessary speed, but follows too closely for following cars to pass in two single-car hops. Fault is primarily on the second driver.)
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way
You don't live in a highly congested urban area and it shows in your comments. 1.5 time the usual distance is insufficient to "afford to brake slowly" per your first comment.
Rewarding tailgaters by moving out of their way in dense traffic where all lanes are full is not helping safety because it will only engender more tailgaters. When traffic is sufficiently sparse that there is a speed difference between lanes, we do move right here. The problem isn't when traffic is fluid nor when it is barely moving.
Democracy is a sheep and two wolves deciding what to have for lunch. Freedom is a well armed sheep contesting the issue
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.
Well I'm 1 year away from 50 and I haven't crashed yet. I guess I will crash a negative number of times between 50 and 60.
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
>This isn't even a new thing to study.
It isn't. When I was at college, a long, long time ago, some friends did a model and simulation of flow breakdown on a highway and showed that it followed exactly the same equations as for coax ethernet (which was the norm at the time).
Knowing these, we can understand that cars behave much like packets in a network when it comes to flow efficiency and the math has all be done. In networks however, we can increase the speed limit and number of lanes until we are at the easy point in the curve. With switched ethernet, everyone gets their own road and the congestion is at the junction.
Maybe that's why Elon Musk took Ted Steven's technically illiterate "Series of Tubes" comments literally and decided to start boring tubes.
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
Bullocks. We're not talking about distances where the speed of light has a noticeable impact.
Synchronization is very easy. Send a timestamped message that you'll brake or accelerate N milliseconds from now, and everyone behind you can do it at the same time.
Dunno what you teach your drivers over there, but there's generally regarded to be one lane, and multiple "overtaking lanes" in all the terminology for most of the countries I have seen driving-school things for. It has almost nothing to do with when you learned to drive unless you're positively ancient. You go into a "faster" lane only to overtake, then pull back in. All your reasoning is WHY you do that, but it's always been the rule of the road too.
If you're parallel-driving, you're an idiot. You're just blocking traffic. If you're going faster on the (passenger side) lanes, you're an idiot. If you're not actually overtaking in the (driver side) lanes, you're an idiot. Admit defeat, fall back, drop in 50 feet behind, what's the big deal? Don't block 2/3rds of the lanes between you and the other car who has no interest in what speed you're doing because HE'S not the one overtaking (or trying to) or in the wrong lane.
Hell, in my country, it's incredibly common to see a 4-lane motorway (freeway) with some idiot in the 3rd lane (i.e. should be overtaking TWO ENTIRE LANES of traffic) when there's nobody else anywhere near him. Everyone has to slow to his speed, bunch up, and try to squeeze past only via the "fastest" overtaking lane. How do you not notice you're a hazard? How do you not realise you're in the wrong when people flash/beep you and bunch up behind? How - once you have the first among-friends-anecdote about the dickhead in lane-3 - do you not think "Oh, maybe I shouldn't be doing that"?
If you want to reduce congestion, it's pretty easy. Smooth driving, look ahead. Leave yourself a gap. Leave that joining car a gap rather than fight (i.e. if both have to slow/speed/intrude to get into something that you could have shared / made clear for them). Drift between lanes (with appropriate signalling) rather than jerk between them. Remove the snap-judgement element, which is what makes drivers behind over-react for their own safety, which propagates backwards and starts causing problems (waves of slow-fast-slow-fast traffic with no obvious cause? Yeah, that's caused by idiots up ahead making rapid lane changes or fighting among themselves, they've done mathematical studies on it).
And, to be honest, for any significant distance on a motorway? Sit in the "slowest" lane, poodle along at "just" 60-70mph. You'll get there roughly the same time as the speeding idiot, you'll be less stressed, you have less to worry about and you can just slide around slow moving vehicles with ease and in your own time. "Cruise" control is appropriately named.
But, for sure, if you have to think about driving safely, or change how you go about driving because you read something on the Internet, you were an idiot before. What other stupid and inconsiderate things are you doing too?
Driving is actually easy, and motorway driving is actually quite relaxing, done right. Because there are no snap-judgements and "let's hope I react fast enough" if you drive properly, on a motorway there isn't a chance of a small child wandering across the road (but, hey, you can see so far in front you'd spot them anyway, right?).
The motorways of countries where road-laws are strict and people stick to them (e.g. Germany) are a joy to drive. Literally EVERYONE just moves over gently as soon as their manoeuvre is complete.
But if you have to THINK about how you drive, reason it out to yourself, take in information from other people to do so, you weren't paying attention in driving school, or you're an idiot that can't just look at the situation and say "Hold on a moment..."
The reason is actually simple, you have no idea how long the guy in front of you is going to take before he notices the light changed. I've easily seen it take 10+ seconds for the guy to notice. Hell, sometimes they take so long that only their car can get through.
Did you know 80 to 90% of the moderators on slashdot wouldn't recognize a troll even if one dragged them under a bridge.
mod up
"Oh, my, some student has handed in his "study" and it made the papers."
On reading the Wired article, and searching for the person quoted in the article, it turns out that "some student" is Berthold Horn - Professor of Computer Science and Engineering at MIT and Liang Wang, a post-doc associate in the CSAI Lab at MIT, supervised by Horn.
Yes, because all studies involving the average human should just use your experience and extrapolate that out to the rest of the 7.4 billion people on the planet.
Does this work because your acceleration is now modelled using the central difference method. This would mean that your acceleration model is no longer subject to first order truncation errors which could be significant if you are actually trying to pick the best speed at any given time by reacting to traffic in your lane.
means that we all suffer more when people don't do the right thing.
also it takes far fewer people doing the wrong thing to muck up traffic.
Absolute statements are never true
But it's not a heuristic on it's own. You also have safe stopping distances for a given speed. And if the car behind is tailgating and forcing you closer to the car in front, then your speed must slow down to maintain safe stopping distance. Safe stopping space for speed is always going to take priority over traffic flow maximisation.
In other words this heuristic should only be used when distances already exceed safe stopping distance.
Of course no human is going to do it. But it's a decent heuristic for automated cars.
Re: your early comment on needing to brake. That's the thing though, the best scenario does not have anyone braking because there is no need. Proper lane changes and zipper merging all make things run smoothly.
How does having a tailgating car force you closer to the car in front of you? The dumbest thing to do when tailgated is to speed up. In fact, I usually slow down so that if there is an accident (more likely with a tailgater) it will be at a lower speed.
get up 15 minutes earlier if you are into your career.
The problem is that when you try to not tailgate, some tailgatyer will insert in front of you
The solution seems obvious to me: fine tailgating, speed camera could do it.
I really hope you didn't just dox APK. It's that information public?
Let's not do this on Slashdot.
const int one = 65536; (Silvermoon, Texture.cs)
SJW, n: "Someone I don't like, and by the way I'm a fuckwit" - AC
Engine braking is also good for dealing with tailgaters. A couple of rounds of slowing down without using the brakes, first just by taking your foot off the accelerator, then if they continue to tailgate, changing down to decelerate faster usually gives them enough doubt about your brake lights working that most of them will drop back for their own safety.
I really hope you didn't just dox APK. It's that information public?
Yeah, he has posted it himself many times. Including address, phone number and e-mail address, which I wouldn't bother posting.
Because that's the heuristic in TFA. And TFS come to that. Read it.
So, because the guy behind me is tailgating, I should also tailgate, and then we can all go 140 mph tailgating each other?
Whoever published this study is a moron.
In an ideal world, sure. In the real world, though, as long as actual humans are driving, it doesn't work.
The lowest rate is at 15 years without accidents.
That's way before 50. More like 31.
Do you not know how academia works?
Lian Wang wrote the paper, the other guy just put his name on it.
its own
100 mph is not nearly as dangerous as you make it out to be, especially with modern cars.
Check out Traffic by Tom Vanderbilt. It's a pretty cool read on this.
The unnecessary braking caused by people not able to maintain constant speed will cause an accordion effect which creates those phantom traffic slowdowns and jams we've all been in.
I'm all for automated vehicles. :-)
Not quite the reasoning. Your insurance rate starts dropping at 25 as long as you maintain a good driving record. If you just start driving at 50, your rate will start at about the same point as if you were 25. The reason the "sweet spot" appears to be 50-60 is that most folks have a steadily decreasing rate starting at 25 or so, and then it starts going up again at 65 when most folks' reaction times and eyesight start to suffer significantly. I've also read that, statistically, the lowest number of crashes per miles driven tends to occur around age 70, but I never see anyone argue that 70 year old people are the best or safest drivers. Something tells me it's not as simple as saying any group of people is better at driving than any other group.
100 mph is not nearly as dangerous as you make it out to be, especially with modern cars.
I used to race motorcycles and even drag raced both cars and motorcycles, so 100+ mph is no stranger to me. But most people do not have the reflexes to go much over 70. It is pretty simple math distance traveled versus reaction time. At 100 mph, you are travelling around 147 feet per second. That's almost 75 feet in 500 milliseconds.
And there is quite a difference when everyone is going near the same speed and when you are trying to go 100 + on a road where most people are driving at 70. A real pucker string moment when that person you are going 30 MPH faster than pulls out in front of you say 20 feet in front of you.You have less than a half second to react, brake and slow enough to not run into them.
Even way back then, I reserved my faster driving for the proper place. And of someone thinks that driving like that on a roadway where most are diving a lot slower - yeah - they are still idiots.
The shepherds did so well protecting the flock that the sheep no longer believed that wolves existed.
That speed is only suitable on long empty highways with high visibility, where you can see if you need to brake or change lanes several seconds beforehand.
I agreed with everything else you said, except for that one observation.
How can you tell that no one else is doing these things? Smart driving tends to look unexceptional, in the same way that elite goal tenders often make the game look easy.
Does perhaps your claim boils down to this: there are more idiots on the road than obvious, distinctive geniuses like Dominik Hasek?
Dominik Hasek
I often regulate my breaking according to the sum of my following distance plus the following distance of the car behind me.
I doubt that one other driver in 100 has even the vaguest perception that I'm attuned to the space around me in all pertinent directions.
I even find this hard to detect in others, and I often look for the most subtle clues. Sometimes I comment to my wife "the driver of that car in the left lane used to drive a motorcycle". Motorcycle drivers—surviving sample—tend to view the entire width of their lane as a resource to be exploited at all times. In a vehicle, that gets compressed down to about one foot of lateral freedom, according to traffic conditions near by (more than a foot starts to alarm people about your lane management).
The number one rule of truly proficient driving: never give the other drivers around you an excuse to think about one thing more than they already failing to fully internalize, unless that one thing is the only thing you want that driver to attend to (in packed conditions, one almost never wants to have this effect on another driver, but it can be quite useful—wielded judiciously—in lesser congestion).
There's a huge correlation between skill and stealth, hence the Wobegon woes.
Illusory superiority
Illusory superiority itself is full of shit, because different people have different standards of competence. Some people value being polite, others value defensive driving, still others value weaving and wending to leave the slings and arrows of outrageous fortune in their rear-view mirror (which is generally covered in black tape).
Surprisingly (not!) we all think we're above average in the attributes we most value.
(My name & email address are in my programs online - I don't hide those but I've never posted my home address publicly online).
I have not done so, but you have, many times.
A quote from APKNTTOOLS_READMEFIRST_InstallHowTo.txt, which indeed is publicly published online by yourself, states:
Send $10 to after a 60 day trial if you like (all versions inclusive past & present) of
APK System Tools for Windows® 2002 + +
To:
Alexander Peter Kowalski
[address follows]
[redacted to be nicer to you than you ever are to anyone else]
So, to sum it up, by making the claim that you hadn't posted your address online, people now know how to easily find your address online, courtesy of yourself.
So you are assuming everyone on the road is using an autonomous vehicle.
No, I am refuting a claim of it being impossible. It is certainly possible to put several autonomous vehicles after each other on the road, and it's possible to make them react at the same time. Thus refuting the claim that it's impossible.
That's true.
But you'll find that 'people that don't have the maturity and will power to actually -work- from home' also 'don't have the maturity and will power to actually -work- in the office, unless your watching them every second.'
Personally, I hate 'bossholes', any team member that consistently forces me to be a 'bosshole' just gets fired. The rest of the team _appreciates_ this.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
About the only Pintos left have V8s and are faster than your overpriced factory tuner.
John McAfee 'It was like that time I hired that Bangkok prostitute; to do my taxes, while I fucked my accountant'
I see a potential problem. Perhaps I'd better RTFA.
If somebody is tailgating me dangerously closely, to equalize the distances fore and aft shouldn't I also tailgate just as closely?
Yeah, definitely RTFA time.
There's no time like the present. Well, the past used to be.
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.
Around Montreal Quebec, its a problem with youth. Although the speed limit in residential streets is 40km (25mph), the youth insist on doing 60km (40mph). On the main thoroughfares add 20km/hr (or 15mph). Our city planners don't believe in synchronized traffic lights, and that lack of synchronization results in "Can I make it to the next light before it turns red" rush.
The second problem is the over abundance of stop signs. In 1.6 kilometer drive(1 mile), there are a dozen stop signs at the
dozen feeder streets. Taxi driver "slide throughs" are the after hours norms.
The above two factors are bad for health. There are more than 3000/cars per day at each stop sign. The polution is heavy, but the city admin does not care. They are all social science graduates (law, or services). The stopsign polution must affect both seniors and the youth. We seniors respect the stops, but the impatient youth just whizz by. We seniors do not race each other or the youth. The youth tend to race each other from the traffic lights.
Yes, the city does not want to spend the money to modernize the lights for traffic flow, mainly because the traffic is thru-traffic. (One municipality sandwiched between source and destination).
Leslie Satenstein Montreal Quebec Canada
I live in a medium city. I've lived in several places. I drive every day.
I've had my car run into twice, but I wasn't driving it at the time.
I attribute not crashing to paying attention and driving defensively. But shit happens and I don't expect my odds are any better than any other moderately defensive driver. I just got lucky. Statistics is like that.
I should use this sig to advertise my book ISBN-13 : 978-1501515132.
Like that old "study" that said 80 km/h was the ideal speed for max throughput (it's not).
80km is the speed at which maximum throughput is *observed*. That you don't like facts doesn't make them wrong.
Below 80km, people lose focus and the number of phone-checkers and lane hoppers cause traffic to flow worse. Above 80km, people leave closer to the "recommended" 2 second distance, which is too high for optimal throughput.
Now, if the car behind me is further back, according to the "study", I should slow down to increase my distance in front and reduce my distance behind. But then of course the car behind me is going to slow again to get back to its old distance, so I keep slowing until I have as much distance in front of me as the car behind me. Now the car in front of me is going to slow down to as well, because he wants as much distance in front of him as behind him. I don't exactly see throughput improving here...
If everyone drove like you, then minimum safe distance is best. Are you asserting you are no better than the average driver? If you aren't average, then extrapolating your personal opinion to everyone would be stupid. So, you are either a bad driver or stupid. Or both. I vote for both.
Learn to love Alaska
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.
No, the 45+ age bracket has the most political power, so they're the ones that could bring about a real inquiry into the insurance industry (which is sorely needed here in the UK). That's why they get the best rates.
Young people are highly represented in fatality and casualty statistics because they generally (are forced to by high insurance prices in the UK) to drive less safe cars. It costs thousands of pounds to insure a 19 year old, thousands more to do that on any kind of mid sized car. So they cant drive anything bigger than an old Fiesta until they're 26... which is the magic age for your first major insurance price drop. They aren't represented in significantly more crashes here in the UK than other age groups but are more represented in casualty and fatailty statistics. Young people tend to have more fatalities per crash and this is mainly due to them having to drive older, less safe cars.
Elderly drivers are more represented in crash statistics, but have fewer fatalities per crash.
But it's older people who can threaten the insurance regime's profit engine, so they never get targeted.
Calling someone a "hater" only means you can not rationally rebut their argument.
Brake lights cause traffic jams.
On a motorway (or any other free flowing carriageway) they create traffic waves rather than jams. Traffic waves are when traffic slows down for a short while and then speeds up with no apparent cause. People doing the brake light shuffle cause these, same as people who lane weave.
Traffic jams are caused by people stopping unnecessarily (or sometimes poor road design).
Keeping a steady speed, and only accelerating and decelerating slowly helps other drivers to match speed when merging
This, also remember to create gaps earlier for the car in front to merge into (merge like a zipper), if you don't you end up stop/starting at the merge point as you have to bring the whole procession to a halt to let the guy in front in.
Calling someone a "hater" only means you can not rationally rebut their argument.
Engine braking is also good for dealing with tailgaters. A couple of rounds of slowing down without using the brakes, first just by taking your foot off the accelerator, then if they continue to tailgate, changing down to decelerate faster usually gives them enough doubt about your brake lights working that most of them will drop back for their own safety.
Alternatively, you could move out of the left lane and let them pass you.
I don't tailgate often, but when passing on the right isn't safe, but a vehicle is obstructing traffic on the left, I will get close to let them know I would like to pass. The drivers who slow down even further and get all self-righteous in their zeal to slow traffic should really have their licenses zapped.
Why start a petty battle, further increasing the danger of the situation, instead of simply letting drivers who want to pass pass?
SWM seeks new sig for a brief fling
Some of us drive in different traffic conditions to you. When people tailgate me, finding a gap to pull into safely lets the tailgater get one space forward in the queue so they can tailgate the next car. It rewards their road-bullying behavior, ensuring they will continue to do it in future, inconveniences me, the car in front that now has someone tailgating them, and the cars in the other lane that I had to pull into. Dealing with the problem in a way that puts a stop to the behavior is better for everyone.
Dunno what you teach your drivers over there, but there's generally regarded to be one lane, and multiple "overtaking lanes" in all the terminology for most of the countries I have seen driving-school things for.
When you have two lanes in the same direction, that terminology, and acting on it, makes sense. When you have, for instance, six lanes in the same direction, it does not. The extra lanes are about increasing capacity, and are intended to be used for long-distance driving rather than just passing slower traffic.
That's the sort of highways we have over here. (Especially in high-population states like California, for instance - I commute on such a 12-lane stretch every day.)
The laws have been adjusted according to this purpose. For instance: Passing on the right is expressly legal in California. On the other hand, excessive lane changes (as you'd have to make to use the "passing" paradigm) are added hazards when the lanes are being used for travel rather than merely passing, and are treated as the infraction called "weaving". Three lane changes (1 1/2 "passes") within one minute is one of the criteria police have used for issuing such citations.
Bantam Dominique roosters crow a four-note song. Once you've heard it as "Happy BIRTHday" you can't NOT hear it that way