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Confusion over what is a "safe following distance" has QUT [(Queensland University of Technology)] road safety researchers calling for a standardised definition to prevent tailgating.
- Tailgating conclusively linked to rear-end crashes
- Most drivers leave less than a 2 second gap between them and the vehicle in front
- Rear-enders account for one in five Queensland crashes
Dr Sebastien Demmel, from QUT's Centre for Accident Research & Road Safety -- Queensland (CARRS-Q), said the results of the study which found 50 per cent of drivers tailgate, was being presented at the 2017 Australasian Road Safety Conference in Perth today.
"This study, for the first time conclusively linked tailgating with rear-end crashes, but we also identified confusion among drivers over what is deemed to be a safe following distance," he said.
"Despite drivers perceiving they are following at a safe distance, our on-road data showed that in reality most don't leave the recommended two to three second gap," he said.
"At some locations 55 per cent of drivers were found to leave less than a two second gap between them and the vehicle in front, and 44 per cent less than a one second [gap]."
A safe following distance is 5 feet. While looking at a smartphone.
(Score: 3, Disagree) by Kilo110 on Thursday October 12 2017, @09:51PM (58 children)
Tailgating is bad and risky, but what about the other side of that issue? Why not also go after those at the root of the issue?
When I see a tailgating driver, I also see a slow moron clogging the passing lane right in front. One guy holding up the left lane often leads to a stack of drivers all tailgating each other out of frustration. Inevitably, you'll see them trying to drive around the one moron holding everyone up by passing in a non-passing lane.
Better lane discipline would lead to much less tailgating, faster travel times, and generally much less road-rage.
(Score: 5, Insightful) by Anonymous Coward on Thursday October 12 2017, @09:55PM (13 children)
Someone may frustrate you, but you choose how you respond to that frustration, and you are responsible for your own behavior.
(Score: 0) by Anonymous Coward on Thursday October 12 2017, @10:59PM (4 children)
I'm not touching you...
I'm not touching you...
I'm NOT touching you...
I'm NOT touching you...
You get the point... one certainly is responsible for one's own behaviour, but at some point, you just take out the cricket bat and go bananas on the guy. And in some cases, people will look at you and go: "good on him, whomever is on the receiving end of that bat, is deserving of what they are getting, in fact, I may just as well join in!". People hogging the passing lane is one of those cases (or it should be).
(Score: 5, Informative) by Anonymous Coward on Thursday October 12 2017, @11:17PM (3 children)
No I certainly do not. Losing one's temper is immature and dangerous any time, and often lethal when driving a deadly weapon (motor vehicle).
(Score: 0) by Anonymous Coward on Friday October 13 2017, @01:51PM (1 child)
Does that mean that you do not approve of *any* military intervention? Am I getting that right? Because that's the equivalent of this between countries.
One man's aggression is another's 'signaling'. I take it you also never flash your lights at anyone?
(Score: 0) by Anonymous Coward on Friday October 13 2017, @02:11PM
I would not approve military operations that are "go bananas". Military operations should be rationally decided, planned and executed.
(Score: 0) by Anonymous Coward on Friday October 13 2017, @05:19PM
Ah the moral absolutist. Hopefully one day you'll realize that people are human and expecting perfectly logical and ethical behavior at all times is simply unrealistic. This will also improve your personal life as you stop trying to judge/fix the world and roll with the madness instead. Do what you can, and otherwise don't let the madness ruin your/other's life.
(Score: 0) by Anonymous Coward on Thursday October 12 2017, @11:07PM (1 child)
Personally, I mounted an extra windshield washer system with a single nozzle mounted just above the rear bumber, and filled it with a yellowish liquid. When these idiots tailgate me, they do not just get frustrated, they get pissed off! Or they at least think they are being pissed on.
(Score: 1, Funny) by Anonymous Coward on Friday October 13 2017, @03:29AM
I had a friend long ago that had one of those volkswagens that had the exhaust pipe mounted straight up in the center of the rear of the vehicle.
He had had it with tailgaters bumping his rear bumper into his flywheel.
He had rigged a small 12V pump so as to feed pump used motor oil into his exhaust line, so it would be ejected through the pipe into the air at windshield level.
Sure enough, one day, I was riding with him and someone else started tailgating.
He told me he had an anti tailgater button, makes any tailgater go away in ten seconds or less. I did not believe him. I pressed it. It did exactly what he said it would do.
I suppose the tailgater probably had to spend at least an hour soaping down his car to get all that motor oil off.
(Score: 2, Troll) by Snotnose on Thursday October 12 2017, @11:44PM (3 children)
I get annoyed, then irritated, then frustrated. Then I do everything I can to get in front of the asshole.
I fail to see the conundrum. If you have a constant stream of traffic passing you on the right (in the USA), you're being tailgated constantly, and the folks who pass you open their sunroofs and give you the finger, you just might be the problem.
tldr; if you drive slow in the fast/passing lane, fuck you with an unlubricated 12" dildo right up the ass.
My ducks are not in a row. I don't know where some of them are, and I'm pretty sure one of them is a turkey.
(Score: 5, Insightful) by AthanasiusKircher on Friday October 13 2017, @02:36AM (2 children)
Slow drivers in passing lanes are a problem. I agree. Tailgating is a separate problem (and generally a MUCH more serious and dangerous issue).
Just because the first problem exists does not justify people's behavior in creating even worse problems.
A few years back, I was on a highway at morning rush hour and fell into one of those situations where some idiot was driving the speed limit in the left lane, and everyone was passing around him on the right. I was several cars back, but kept maintaining a safe distance, even though that caused even further idiots to drive around me. At some point, someone cut someone off three cars in front of me. Car behind slammed into the first and was probably totaled. Car behind him swerved, clipped the second car, and flipped over and went off the highway. Car behind him slammed hard into the first and spun around backwards on the highway. I had room, so did a quick lane shift and got out of the mess... and lucky for the person in front of me, because the three or so tailgaters behind me also slammed into each other. Pretty sure if I had been following in the general stream of tailgaters (with their amount of distance) in front and behind me, I'd have been seriously injured if not dead, crunched up in a giant pile of cars.
I've never felt my heart pounding as much as after getting out of that incident. And I barely had room to do so. You may think it's harmless to tailgate the jerk riding in the left lane, or to swerve around him cutting people off along the way while you give him the finger... but keep in mind you're actually doing something freakin' dangerous and could kill yourself or someone else when you've going at highway speed.
Is it really worth it just because someone's annoying you or you might spend an extra couple minutes on the highway? (Unless you have a long commute, going 5-10 mph faster, which is often the differential that creates the road rage in the left lane, is generally not going to save you so much time that it's worth risking your life... IMHO.)
(Score: 4, Informative) by FakeBeldin on Friday October 13 2017, @08:32AM
And if you do have a long commute, you'd be better off leaving earlier.
Speeding is necessary in some cases (e.g. medical emergencies). Commuting isn't one of those cases. Leave earlier and accept that there are other vehicles on the road.
(Score: 3, Informative) by Phoenix666 on Friday October 13 2017, @10:56AM
And potholes. Don't forget potholes. If you tailgate you might not have enough time to spot and avoid potholes on the road, and could find yourself losing an hour replacing a tire. At night. In the rain.
Safe following distance is essential.
Washington DC delenda est.
(Score: 3, Touché) by Kilo110 on Friday October 13 2017, @01:48AM (1 child)
Yes, great line to use to teach children. But it doesn't account for the practicalities of human nature.
(Score: 2) by darkfeline on Friday October 13 2017, @08:07PM
Which is why self-driving cars are going to take over.
Join the SDF Public Access UNIX System today!
(Score: 4, Touché) by c0lo on Thursday October 12 2017, @09:59PM (1 child)
Methinks that the Queensland drivers would be quite happy for that guy to stay into the left lane.
https://www.youtube.com/watch?v=aoFiw2jMy-0 https://soylentnews.org/~MichaelDavidCrawford
(Score: 2) by MostCynical on Friday October 13 2017, @02:13AM
A few years ago, they had a campaign to try and keep them in one lane, and not keep changing lanes.. It worked: now they sit in a lane and do whatever speed- usually 20 under, or 20 overr, the speed limit.
"I guess once you start doubting, there's no end to it." -Batou, Ghost in the Shell: Stand Alone Complex
(Score: 4, Interesting) by NewNic on Thursday October 12 2017, @10:06PM (7 children)
If I am travelling at a reasonable speed (at or above the speed limit, or constrained by traffic in front of me), and I pick up a tailgater, I slow down.
This is only safe behaviour. I am forcing the driver behind to leave a safe distance between us, by making 2 seconds correspond to a shorter distance. I might also tap the brakes a few times if they don't get the hint. If they pass me, I'm fine with that. Let them tailgate some other person.
lib·er·tar·i·an·ism ˌlibərˈterēənizəm/ noun: Magical thinking that useful idiots mistake for serious political theory
(Score: 5, Informative) by Valkor on Thursday October 12 2017, @11:29PM
Hit the windshield washer button. If you have one for the rear, use it. The spray will get on them, too.
(Score: 3, Informative) by frojack on Friday October 13 2017, @07:21AM (5 children)
Its called a "break check". Pretty stupid actually. The person you hurt is likely to be the person behind the tailgater, or the one in the lane the tailgater dives into to avoid your break check.
All you need do is slow down evenly and not suddenly. They will go around.
No, you are mistaken. I've always had this sig.
(Score: 2) by Rivenaleem on Friday October 13 2017, @08:59AM
How do you hurt the guy behind the tailgater? Unless that person is also tailgating...
(Score: 3, Informative) by RedBear on Friday October 13 2017, @11:07AM (3 children)
No, it's called a "brake check". But tapping on the brakes enough to light up the brake lights momentarily, without reducing speed by any meaningful amount, is not in any way the same thing as slamming on the brakes long enough to endanger anyone following too closely. Don't confuse the two ends of the spectrum. One is an attempt to surreptitiously get the tailgater to decide to either back off to a safe distance or pass, the other is a crime. Nobody should be "diving" anywhere from your brake lights briefly flashing.
There are many road situations where the tailgater has no safe way to turn off, change lanes or get around you. If you haven't encountered any, I encourage you to take a few long road trips. Slowing down is rarely a real solution to the tailgating problem. You'll just piss off a stupid, road-rage prone driver even more. It is tailgating that is the most dangerous behavior. And all of the impatient a-holes on the freeway that will jump into the smallest gap between vehicles to instantly negate the safe distance you were trying to keep at 80mph. That's always fun.
I've lost count of the number of times I've been tailgated by an impatient so-and-so who seems to want to drive home at 15mph above the posted speed limit, in pitch darkness and pouring rain on a winding, heavily forested mountain road with blind curves, no turnouts, no safe shoulders and double-solid no-passing lines on the road for miles and miles. So much fun looking for unmarked, barely visible turnouts in the dark while driving a top-heavy 30-foot RV around what feel like 360-degree turns that are still inexplicably posted as 50mph zones. Good times. Being tailgated is the icing on the cake.
¯\_ʕ◔.◔ʔ_/¯ LOL. I dunno. I'm just a bear.
... Peace out. Got bear stuff to do. 彡ʕ⌐■.■ʔ
(Score: 4, Informative) by PiMuNu on Friday October 13 2017, @03:18PM (2 children)
> Slowing down is rarely a real solution to the tailgating problem.
Not true. If you slow down you
(a) increase the gap to the car in front, allowing a controlled deceleration in the event of a problem (e.g. queue ahead)
(b) slow down the car behind, helping them to slow down in a controlled manner in the event of a problem (e.g. queue ahead)
It seems like exactly the correct response.
(Score: 2) by tangomargarine on Friday October 13 2017, @04:04PM
Unless you're on a country highway with only one lane in each direction. Near me they seem to love making them no-passing zones approximately 85% of their length.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 2) by NewNic on Friday October 13 2017, @05:42PM
Exactly. I have avoided several accidents by realizing that the person behind me was going to hit the rear of my car as I braked, then eased up on my braking, giving the idiot behind more space.
lib·er·tar·i·an·ism ˌlibərˈterēənizəm/ noun: Magical thinking that useful idiots mistake for serious political theory
(Score: 4, Informative) by NewNic on Thursday October 12 2017, @10:11PM (9 children)
OK, so what about this situation:
I am in the left-most lane, because it is the only carpool lane.
I am travelling at speed, but then, I see that traffic half a mile ahead is travelling slowly. Should I:
1. Keep travelling at the speed until I get close to the slow moving traffic ahead, then slam on the brakes.
2. Move out of the carpool lane OR
3. Slow down gently and early, until I reach the slow moving traffic ahead.
Note that option 3 results in my (and cars following me) arrival at home at exactly the same time as option 1.
lib·er·tar·i·an·ism ˌlibərˈterēənizəm/ noun: Magical thinking that useful idiots mistake for serious political theory
(Score: 4, Insightful) by Grishnakh on Thursday October 12 2017, @11:23PM (4 children)
The whole left-lane-is-for-passing thing falls apart on multi-lane highways where the lanes have specialized uses. If the left lane is an HOV lane, then sorry, if you're an HOV driver you have the right to stay there, and passers have to pass on the right. (Yeah, I know that's really not ideal, but you can't have it both ways.) And also, if the highway uses left exits, and you're taking an exit in the next few miles that's on the left, then it's not unreasonable for you to stay in the left lane until then, though for traffic's sake you might want to delay moving left until you get closer, but that depends on how heavy traffic is (if it's really heavy, you'll want to move over earlier or else you could miss your exit).
Being really strict with lane discipline only works in places where they designed the highway with that in mind, and they don't have ANY left exits, nor any HOV lane.
(Score: 2) by slinches on Friday October 13 2017, @12:04AM (3 children)
You're right. We should get rid of the HOV lane.
Seriously, it's a huge disruption. The people moving across all lanes as quickly as possible by braking and waiting for a gap slow down traffic for everyone else. Without that lane, traffic can be heavy but flow smoothly. I saw it happen when they added an HOV lane to a freeway I drive most days to work. Before the new lane, everyone cruised at about 45-55mph. It was dense traffic, but it moved. Now with an extra lane, it's stop and go averaging 20mph or less in the peak of rush hour.
(Score: 0) by Anonymous Coward on Friday October 13 2017, @03:24AM (1 child)
or make it pay-to-play, like on I-405 in Seattle area, or various HOV lanes in California. The cameras on the lanes can see your license plate AND see if there's a passenger in front with the driver or not, and they toll you accordingly. In Washington, they have a phone # where you can rat violators out, too.
(Score: 2) by maxwell demon on Friday October 13 2017, @05:21AM
So three people on the rear seat don't count if there's nobody on the second front seat? It doesn't sound right to make the cost dependent on the passenger sitting at the "correct" place.
OTOH this might give inflatable dolls a new use. ;-)
The Tao of math: The numbers you can count are not the real numbers.
(Score: 2) by frojack on Friday October 13 2017, @07:36AM
Agreed. There is no engineering or traffic safety reason to have HOV lanes. It totally fucks up a well defined traffic system that has been designed and improved with scientific traffic and accident statistics since the 30s. People are in the wrong lane going the wrong speed, and the whole road way is impacted.
Since the invention of the HOV, We've been taught that lane choice based on speed and destination is wrong. We've been taught that lane choice is for political reasons.
Someone mentioned Seattle. One of the worst examples of political engineering you can imagine. The pay to drive the 405 is just a money grab. Rent seeking using a Federally funded freeway that was paid for by tax dollars. It does not solve any problem. Traffic does not move faster. And they still have the an ever increasing number of homeless persons living under the freeway every year. A money grab in the name of social engineering.
No, you are mistaken. I've always had this sig.
(Score: 3, Funny) by Anonymous Coward on Thursday October 12 2017, @11:36PM (2 children)
Obviously the correct answer is to brake as hard as you can a the last minute. Bonus points if you can magnify any waves of stopped traffic.
(Traffic jams move in waves. You win if you've made the crest of stopped traffic two or three cars longer than it was before.)
This has the added advantage of reducing your gas mileage. The optimal driving pattern should have your brake lights strobing: *GAS* *BRAKE* *GAS* *BRAKE* *GAS* *BRAKE* *GAS* *BREAK*!!!
That's what everybody else does, and if I've learned one thing about humans, if everybody else jumps off a cliff, don't be the last one to take a dive!
(Score: 2) by choose another one on Friday October 13 2017, @08:19AM
*confused* - surely you want to be last, not first, when jumping off a cliff?
Doesn't landing on a big pile of bodies beat landing on rocks and then being landed on by other bodies?
(Score: 2, Funny) by Anonymous Coward on Friday October 13 2017, @08:24AM
http://news.bbc.co.uk/2/hi/europe/4665511.stm [bbc.co.uk]
Better to be late than belated ;).
(Score: 0) by Anonymous Coward on Friday October 13 2017, @01:26AM
Your note about arriving at the same time is incorrect. Sudden braking sends waves of similar braking throughout everyone traveling in that area. It's the primary cause of most traffic jams. The only option if you want to keep traffic flowing smoothly for everyone and arrive at your destination the fastest is #3. #2 will cause others to break when you move into their lane thus forcing them to apply #1. It only takes a smaller percentage of people applying #3 to clear up traffic jams. There are tons of studies backing this up.
Driving instruction really sucks all over the work. People need far more retraining every year. You should be required to take drivers ed every few years.
(Score: 5, Insightful) by Thexalon on Thursday October 12 2017, @10:18PM (4 children)
Another aspect of this that just makes things worse: More than a few problems are caused by people being passed speeding up in response. So even if everyone's being being disciplined about what lane they are in, the person going 70 who pulls out to pass someone going 55 might find themselves being half of a moving roadblock as the person who was going 55 speeds up to 70. And if they decide to give up on the pass and pull back into the right lane, the slowpoke slows right back down again with them. All of this drives the person behind them that wants to go 85 absolutely bonkers, as well as the person who is trying to go 70 but can't let the person behind them by.
The only thing that stops a bad guy with a compiler is a good guy with a compiler.
(Score: 1) by anubi on Friday October 13 2017, @03:44AM (3 children)
I find the very situation you describe happens to me a lot in my van. I really don't want to drive all that fast, as I am not as maneuverable as smaller cars built for speed, and I can do a helluva lot of damage with the amount of kinetic energy supposedly under my control.
If someone tries to pass, I do everything I can to help him out.
Once he is ahead of me, he's gone.
I would *much* rather have him in ahead of me than him being penned up behind me, stewing.
I hate to be an asshole by driving too slow, but I would rather be an asshole than a murderer.
If I feel I am barely in control of this thing, I'm driving too damned fast.
"Prove all things; hold fast that which is good." [KJV: I Thessalonians 5:21]
(Score: 2) by frojack on Friday October 13 2017, @07:49AM
As someone who drives long distances the thing that pisses me off is big trucks bringing the high speed lane down to 45 as they pull out and creep past the big truck going 44.
I call it the Outbound Truck Sort. It will end up using all available lanes.
This happens on the road out of town in any city that attracts more than two trucks. They are all trying to accelerate to highway speed. Some have heavier loads, and it takes them a mile or two more. But the clown hauling potato chips has to get to 65 ahead of that guy pulling heavy loads.
No, you are mistaken. I've always had this sig.
(Score: 2) by tangomargarine on Friday October 13 2017, @03:59PM
A very good point, which the exception I follow of people who are wandering side-to-side in their lane. This probably means they're distracted/inebriated, in which case I feel safer getting in front of them in case they decided to randomly hit the brakes or swerve into somebody in the other lane or something--minimize the ways they could hit me. Of course, when you do decide to pass them, it behooves you to do so as quickly as possible.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 0) by Anonymous Coward on Friday October 13 2017, @05:36PM
This is something I follow all the time.
If you're not going fast, that's fine, just don't clog things up. If someone is just sitting next to you for a while, either slow down or speed up depending on the situation.
Of course, people promptly get discouraged from following this after someone speeds past them, enters their lane, and then slows down like crazy for no apparent reason.
(Score: 2) by LoRdTAW on Thursday October 12 2017, @10:28PM (16 children)
The problem is the slow moron in the passing/hammer lane is obeying the speed limit and well within their right to do so. Patience is the problem.
(Score: 0) by Anonymous Coward on Thursday October 12 2017, @10:33PM (6 children)
I might be going 65, but I really want to go 90. I just can't afford to be dealing with cops. Ditch the damn speed limit, and I won't feel a need to cause such problems.
No, I do not wish to go 55 in the other lane, with frequent slowdowns to 45 when merging.
(Score: 3, Interesting) by Arik on Thursday October 12 2017, @10:43PM (1 child)
I sympathize. Fortunately the main place I might want to go 90 did actually get raised to 80, and as long as you're >=10 below it's generally too petty for them to bother hitting the lights. I'm really ok with that, it's close enough. But somehow it's still a problem once you figure in all the other drivers. A bunch hold 65-70 the whole way, they usually stay in the right lane but when mister 69mph is in front of me passing mr 65mph... grrr. And then there's still the occasional guy that zooms up on my tail out of nowhere doing ~100 and trying to pass on the right where it isn't safe. Still, I do think increasing the speed limit has probably reduced the accidents. May have increased the average severity though. I'll see if I can find the numbers.
If laughter is the best medicine, who are the best doctors?
(Score: 2) by frojack on Friday October 13 2017, @08:12AM
Probably because those numbers don't exist. I've looked. You can find lots of claims, but those are usually speculative (and politically motivated) and aren't comparing the same traffic mix on the same roads.
Mostly what you find is that the improvement in automobiles reduces accidents and highway deaths to such a great degree that an increase of speed limits from 75 to 80 has zero measurable effect.
Try that 80mph in a 50-60's era car and you would see a lot more accidents, and a lot more deadly ones. Those cars were hanging on for dear life at 80. Modern cars drive at 80 like your doing 45.
No, you are mistaken. I've always had this sig.
(Score: 2) by bob_super on Thursday October 12 2017, @11:02PM (3 children)
STAY IN THE RIGHTMOST LANE UNLESS YOU'RE PASSING SOMEONE! CHANGING LANES AS NEEDED IS NOT A DISEASE, IT'S THE RULE!
This reminder of the law provided to you by the billions of hours and dollars wasted in traffic jams caused by improper lane usage. TMYK.
(Score: 2, Insightful) by Anonymous Coward on Thursday October 12 2017, @11:13PM
I
am
passing someone. There's someone in the right lane going 55. I'm going 65 and want to pass them. I want to go 75, and I think it would be perfectly safe to go 75, but cops will get me if I go more than about 2 miles over the legal limit of 65, so I won't go faster than 65.
Meanwhile there's someone behind me who wants to go 85 and is having a temper tantrum like a 2 year old that I'm in the left lane in his way. He's so crazy right now he doesn't see whether I'm passing someone or not. He's blinded by rage and endangering us all and like all people having an angry outburst wants to blame other people instead of his own misbehavior.
(Score: 2, Touché) by Arik on Thursday October 12 2017, @11:22PM
And If you really must do 90+, I'll happily move over and let you past - just as soon as I complete what I'm doing so it's safe to do so.
Only thing that pisses me off is jackasses that won't wait for that and endanger everyone trying to pass on the right, while speeding, and close to other vehicles. That's really not cool.
If laughter is the best medicine, who are the best doctors?
(Score: 0) by Anonymous Coward on Friday October 13 2017, @08:45AM
Yes people shouldn't be hogging the passing lane if there's a perfectly empty lane beside, nor should they be going slower than other traffic beside if they're in the passing lane.
BUT a bigger (and as common if not more common) problem are the asshole tailgaters who do dangerous stuff because they don't want to wait for me to pass the other traffic even though:
1) I am actually in the process of passing slower traffic
2) I am at or even a bit over the speed limit.
3) I will move aside once I'm safely past the slower traffic ( cutting right in front is not safe even if the other vehicle is slower)
Those assholes smugly insist that just because I'm in the passing lane and traveling slower than they want to it means I must move aside.
But that's BULLSHIT. It is FAR WORSE for traffic flow if everyone traveling at the speed limit in the fast lane has to slow down to move into the already packed slower lane (slowing it down further or worse- causing "traffic jam waves") just because a few tailgaters behind want to go way faster than the speed limit.
(Score: 2) by NewNic on Thursday October 12 2017, @11:21PM (7 children)
And how often are the driving at the speed limit, as indicated by an optimistic speedometer? Many speedometers read 3-5mph above actual speed at 50+ mph. Regulations appear to mostly allow -0% to +(10% + ~5kph), so at 55mph, the speedometer could read ~65mph.
If they are in a jurisdiction where the passing lanes are just that: for passing, then they should pull over when not overtaking or following another vehicle, irrespective of speed.
lib·er·tar·i·an·ism ˌlibərˈterēənizəm/ noun: Magical thinking that useful idiots mistake for serious political theory
(Score: 2) by Arik on Friday October 13 2017, @02:04AM (6 children)
If laughter is the best medicine, who are the best doctors?
(Score: 0) by Anonymous Coward on Friday October 13 2017, @03:30AM
uh, it doesn't work that way. If you're really worried about it, get a GPS speedometer app for your phone. Chances are, at ~50-70 mph, your speedo reads about 1-3 MPH higher than GPS speedo will read.
The car mags periodically do stories about just this, as does Consumer Reports.
At least in the US, potential liability for having a speedometer indicating less than actual speed is...huge.
(Score: 1, Offtopic) by tangomargarine on Friday October 13 2017, @03:52PM (3 children)
Speedometer readout isn't reliable 100% of the time. For example, my car gets rather bad traction in the winter, even with my winter tires on, and when I'm spinning my wheels on ice/snow at an intersection to get going, I've had the speedometer climb to 20mph before I actually start moving. So presumably it measures wheel rotation or something rather than actual velocity. Plus, can't your speedometer readout be off if you have the wrong size of tires mounted? Because the diameter is screwed up so the measurement is based on an assumption with drift from expected values.
I've never looked it up but I imagine the problem of how to precisely measure your speed without GPS is a pretty interesting one mathematically. Differentials must be involved somehow? I really sucked at advanced math :P
(2009 manual Toyota Corolla)
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 2) by Arik on Friday October 13 2017, @06:07PM (2 children)
That's exactly correct. Which means that the only time it's inherently inaccurate is when, as you described, you lose traction.
Other than that, it's a matter of calibration. As someone else already mentioned, it's actually illegal for it to be calibrated too low (i.e. to show 49 when you're actually doing 50) but it's not illegal for it to be somewhat too high (if it says you're doing 52 when you're doing 50, that's just fine, legally.) This means that when you buy a car it's expected to be calibrated too high. Test it with a stopwatch on a nice flat stretch of road and you can get a pretty accurate picture of exactly how high it is. Radar signs and GPS are other instruments that can be used to compare. The effective calibration changes slowly as your tires wear and of course quite quickly and drastically if you put on new tires of a different size, so it's necessary for the adjustment to exist.
"I've never looked it up but I imagine the problem of how to precisely measure your speed without GPS is a pretty interesting one mathematically."
Nah, it's dead easy, simple. Velocity=Distance/Time
You need a relatively straight flat bit of road with known marked lengths. These are widely available. You get up to a given steady speed per your speedometer, click the stopwatch as you pass one marker, click again as you pass the second. If it's a one mile section, and it took 60 seconds, that's 60 miles per hour. (Sub kilometres if that's what you use, it works out just exactly the same regardless of unit.)
1m/60s=Xmps
but we don't actually want to know miles per second, we're looking for miles per hour, and it's going to be easier to do the conversion here than later, so it's 3600 seconds/hour of course. I'm using miles but if you prefer k just substitute it consistently and the formula works exactly the same. For that matter you can use it for inches per week or parsecs per season, it's the same formula. Anyhow.
1m/(60/3600)h simplify to
1m/(1/60)h
60mph
Of course that's the easiest case, what if it isn't 60 seconds, but something odd, like 57?
x=1m/(57/3600)h simplify to
x=1m/(63r9/57)h
x=63+(9/57)mph
or alternatively simplify to
x=1m/(.95/60)h
x=63.1578947368... (the same dang thing.)
If laughter is the best medicine, who are the best doctors?
(Score: 2) by tangomargarine on Friday October 13 2017, @06:22PM (1 child)
No, I mean difficult for the engineers who design the car. The car has to measure speed without using visual cues or the outside world at all beyond the tires.
"Is that really true?" "I just spent the last hour telling you to think for yourself! Didn't you hear anything I said?"
(Score: 1) by Arik on Friday October 13 2017, @06:36PM
What internal sensor that drives the speedometer actually measures is effectively the rate of rotation of the wheels. Multiply that by the circumference of the tires to get your actual velocity. (And this is why whether it's the old-fashioned cable-driven speedometer or some new digital sensor there still has to be a way to calibrate it for the actual circumference of the tires in use.)
Velocity = Rotations_per_time_unit multiplied by Tire_circumference. So 60rpm with tires 2m circumference means 120m/m or 2m/s.
If laughter is the best medicine, who are the best doctors?
(Score: 2) by NewNic on Friday October 13 2017, @05:45PM
Not hard, correct.
How many people actually do it? Very few.
lib·er·tar·i·an·ism ˌlibərˈterēənizəm/ noun: Magical thinking that useful idiots mistake for serious political theory
(Score: 0) by Anonymous Coward on Friday October 13 2017, @02:43PM
No they are not in the right. Most states require you to move over to allow faster traffic to overtake you. THIS INCLUDES IF THEY ARE SPEEDING.
That's why you see signs saying slower traffic MUST keep right.
(Score: 0) by Anonymous Coward on Friday October 13 2017, @02:01AM
Take my commute then. 5 miles long of people going slow. But everyone has to be RIGHT on your ass as they do not want to let you in front of them from the other lane. The sin of the dude in front? He is going the speed limit.
Driving too close under almost all circumstance is dangerous. You just want to justify your actions.
(Score: 2) by JoeMerchant on Friday October 13 2017, @11:51AM
Safe following distance is infinite, stay off the road.
Sociologically, if you follow too far behind you are more subject to people pulling out in front of you - a certain percentage of those people show poor judgement and create dangerous situations.
Psychologically, if you're too far behind you can become less engaged and less attentive to the driving task in general which significantly increases the risk of collision due to excessive reaction times.
Realistically, the old "three second rule" is usually a good place to be - far enough to see emerging hazards with ample time to react, but not so far that there's nothing to pay attention to and also close enough to deter persons with a high speed differential from guessing poorly that they might just jump in front of you.
If you're a robot, with good quality communication with the robot in front of you, in decently maintained vehicles with reliable performance characteristics, about a quarter car length not only saves fuel and road space, but also should be ample space for reasonable safety concerns.
As for lane discipline - sure, that's a great idea - but as a reference point: my father in law is 86 years old, has terrible night vision and seriously impaired vision in bright conditions, yet just two weeks ago he was driving 20 miles round trip every week to WalMart. He is far from alone. In the real world, campers in the left lane are quite annoying, but far from the most dangerous things on the road.
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