Slashdot Mirror
The Laws of Physics Trump Traffic Laws
New submitter HeLLFiRe1151 sends this quote from Physics Central:
"Here's a practical application for your physics education: using math to successfully beat a traffic ticket in court. Dmitri Krioukov, a physicist based at the University of California San Diego, did just that to avoid paying a fee for (purportedly) running a stop sign. Krioukov not only proved his innocence, but he also posted a paper detailing his argument online (PDF) on the arXiv server."
As a result of this unfortunate coincidence, the O's perception of reality did not properly re ect reality.
It's too bad that statement cannot be quickly supported in many other cases.
Damn_registrars has no butt-hole. Damn_registrars has no use for a butt-hole.
Relative to my car, I was travelling at virtually 0 mph!
When another car partially blocked the officer's view of Krioukov's car momentarily, the officer could have missed the brief yet crucial timing of his stop. At least, that's Krioukov's version of the case.
Physics explained what the officer saw (or thought he saw) but another car explains what the officer didn't see (Krioukov stopping at the stop sign).
Years ago I was pulled over by a cop who claimed I was going 45 in a 30, which I knew to be complete bullshit. I was driving a car that could barely produce 70hp under really great conditions, with 500+ pounds of friends in the car (in addition to my own mass) and had just come to a complete stop and made a right-hand turn less than 100 yards prior. In other words, the cop was claiming that my woefully underpowered car from the 70s was accelerating like a modern Porsche.
He handed me my ticket, and I went to the court hearing at the scheduled time, date, and location. In that county the first meeting is with the DA, you have no option to see a judge that day no matter how much you ask for it. That county was over an hour's drive from work, a place I had never visited prior to the date of the offense. The DA made me an offer; take a plea bargain - which would not be reported to my insurance so long as I was not ticketed in their county again for a year (and carrier a lesser fine) - or come back at a later date to plea my case before a judge.
I decided my time was worth more than that, and took the plea. I could have taken the second hearing to plead my case before a judge, but the amount it cost me to drive there and back, plus time taken off of work, was likely more than the small fine I paid them that day.
That said, congrats to the professor for so handily showing the error in the cop's measurement without making them look like a baboon.
Damn_registrars has no butt-hole. Damn_registrars has no use for a butt-hole.
The article was posted on April 1. (Need I say any more?) See the discussion on the PhysicsBuzz blog for details.
http://physicsbuzz.physicscentral.com/2012/04/physicist-uses-math-to-beat-traffic.html
The vast majority of stop signs are stupid and should be replaced with yield signs.
http://arxiv.org/abs/1204.0162
The Proof of Innocence
Dmitri Krioukov
(Submitted on 1 Apr 2012)
A way to fight your traffic tickets. The paper was awarded a special prize of $400 that the author did not have to pay to the state of California.
If you think this really happened, find a citation for the case that doesn't end up back at this same article.
It turns out that humans are really poor at estimating velocity unless they conform to Newtonian accelerations very closely.. While there has been a lot of research on these issues, I'd like to refer to one of my favorite papers, Sverker Runeson's 1975 paper "Constant velocity — Not perceived as such".
http://www.springerlink.com/content/nt61hh074k7123q5/
Nothing new, I say. I've often seen traffic laws being trumped by nothing less than a generous show of cleavage, which always seemed to defy at least one of the physics laws, namely gravity.
I always get stuck trying to figure out why the triangle has so many sides. It does gives me something to do while I wait for it to turn green.
---
ECHELON is a government program to find words like bomb, jihad, plutonium, assassinate, and anarchy.
I once used physics to argue that a speeding ticket I received was bogus. I explained that even if I was traveling at the speed the officer claimed (unlikely in the underpowered subcompact I was driving, since I'd just gotten on the freeway), he could not have caught up with me and paced me at that speed in that short distance. I also suggested that a more likely explanation for the ticket was a bumper sticker which identified me as gay, and the fact that I was leaving a (peaceful) civil rights demonstration. (This was in the Midwest, in the 90s.) I was still found guilty, but the full fine and points on my license were not assessed.
http://alternatives.rzero.com/
tl;dr: Bullshitter claims his $10k Toyota Yaris has better breaking and acceleration than a $60k sports car; court fails to realize that if bullshitter's car were capable of accelerating that fast, then he's guilty of a more expensive ticket for gunning it from the stop sign (display of acceleration is usually a larger fine than running a stop sign).
Also, I'm pretty sure most places have a minimum prescribed stopping time. Bullshitter's graphs do not have ANY stop time.
Are you sure this isn't a plot line the Big Bang Sitcom?
No. This story is vaguely interesting.
sustainable living
a) a physicist professor (postdoc, well-known in his field worldwide) at my university was ticketed for speeding based on a radar gun reading. In court, he presented an analysis that showed that a radar gun reading would be inaccurate under the conditions where used. The judge determined that the analysis was irrelevant and fined the prof.
b) I was involved in an automobile accident. I was cited for running into the other car. A physicist friend of mine and I put together an analysis based on physics that showed that the other car had to have run into my car. It was pretty cool because it so closely matched what happened (physics works!). However, my insurance company, the prosecutor and my attorney all dismissed the analysis as irrelevant.
Agreed. You guys over in the States put Stop signs at almost every intersection. Was surprising to me as an Australian the first time I drove over there ... in AU we tend to put stop signs only on the occasional intersection where the view of potential oncoming traffic is obstructed for some reason (e.g. there's a tall hedge along the side of the road until just before the intersection). But in the absence of any such obstructions, the ubiquitous Give Way (equivalent to US Yield) sign is used instead.
This, in combination with the considerably lower speed limits in suburban/residential areas, makes getting around suburbia in the US a lot slower than I was used to.
Remind me to do that the next time we are in court.
"lightknight, you've been accused of speeding. How do you plead?"
"Your honour, let's talk firmware. I will show you, as a Computer Scientist, in hexadecimal, where the error in the code of that radar device exists."
"Case dismissed. Now, can you help us with our printer? It keeps printing blank pages."
I am John Hurt.
TL;DR TL;DR: Throw numbers at people who don't understand what the numbers mean, and you can convince anyone of anything
This argument is a shameless piece of sophistry.
It's central argument is "I did stop; a car just passed in front of me and you didn't see.". This is then expanded into 4 pages of unnecessary and probably disingenuous over-analysis.
The entire argument breaks down in FIG 5. Leaving aside this nonsense of measuring angular speed(The human brain interpolates just fine), the author compares two curves in which the equated angular speeds of the car do not translate into the same linear speed. Indeed, at the occlusion point at t~1.5 s, the car corressponding to the blue curve would be travelling at 15m/s, verses the car at constant 8m/s that it is being compared to.
And this is even before we begin talking about how the author is really comparing a car at constant speed to one which reverses back into the stop sign and then drives forward.
I think this kind of thing is described as "sophomoric", and in that that word describes a second year student who is full of their own knowledge with no concept of their own ignorance, I would have to label it as such. The cop was right, pay your ticket Mr. Krioukov, and don't darken the door of the maths department for a very long time.
May the Maths Be with you!
I was always into photography and this was the 70s. My father got ticketed for parking on a cross walk in our small town around midnight. It was the dead of winter and snow covered all the streets. He wanted to fight it so I photographed the place in the middle of the day showing how thoroughly the snow covered the streets making it impossible to see the cross walks. The judge took one look at the photos and motioned for the cop to approach the bench where he chewed him out for wasting his time on such a ridiculous case. It is possible to fight tickets with evidence but so rarely do people have evidence to fight them with.
Traffic cop is ultimately one of the most important law enforcement jobs in America. They serve more arrest warrants than anybody else and are the ones most likely to be visible to the population at large. Now, if the officer didn't see the car drive through without stopping, then the ticket shouldn't have been issued.
"But officer, since I didn't observe the stop sign, it was both there and not there at the same time. It was there after YOU observed it, but by that time I was already gone!"
When the copyright term is "forever minus a day", live every day like it's the last.
Speed limit on the main street between myself and the nearest 24-hr convenience store half a mile away was 45 (I know, I should have walked. But all I wanted was to get it over with so I could sleep). I got pulled over for "drag racing" even though the streets were entirely empty other than myself and a cop waiting on a side road. To be fair, I was getting up to speed limit as quickly as possible so I could get it over with. But I was also "paced" at 60, which means he did not clock me but instead estimated my speed based on speeding up to catch up to me after turning off his side street. He included the streets where all this happened, so this gave me all the distances between incidences that I needed.
I used simple integrals to show the velocity/position relationship, along with the factory specifications of my car. End result is that the judge said he had no idea at all what I was talking about, and the ticket was dismissed because "it sounded right".
Ugg... A police force may not be able to stop a "real" crime from occurring or even solve it once it has. But, It could be prevented by making the police in an area more visible. I.E. traffic tickets generate revenue for the police, safer roads for motorists, and deterrence for criminals. There are more benefits if you are willing to disband the mentality that the police are largely out there to waste your time and their own.
Generally speaking, highway patrol and state troopers will always cite you for an infraction. Town and city cops will let things slide depending on your attitude.
of arguing "I did stop, but the officer's view was obstructed by another vehicle and hence he couldn't have seen whether I did or did not" and having the officer agree that his view was obstructed.
I wish cops would just not pick people on the little tiny things and just let things slide, unless its BLOODY obvious.
Running a stop sign is not a tiny little thing. If the officer actually observed the complete failure to properly obey the STOP sign, a ticket should have been issued.
Cars failing to stop ARE a safety issue. And if the law was not being vigorously enforced, there are many jerks on the road purposefully ignoring STOP signs or red lights when they feel they can get away with it -- road safety would be much worse.
Lives are saved when people don't run stop signs because they're afraid of getting a ticket.
I wish cops would just not pick people on the little tiny things and just let things slide, unless its BLOODY obvious.
Cops shouldn't let things slide they should just be more certain when they issue a ticket. IE they should not make an assumption about a violation, they should actually witness it (or get testimony from a witness). Ever been driving and wonder if someone on a cross street is going to stop? Unwittingly, many people that roll stop signs slow down cross traffic resulting in delaying when the 'roller' would be able to pull out if they had just stop so everyone knows what they are doing. People who only use their blinker 'when necessary' never see the person they nearly hit because no one knew what the hell they were doing.
Its way overdue for teachers to be obsolete, except helping the 'challenged' few, s burn those text books, put all courses online and exams online, and marking online, what a teachers for again? Keeping the peace? taking roll calls?
Making sure YOU took the test.
not sure if sarcasm, or real. But I'll bite.
Teachers are there to keep our sanity. Humans need social interaction. Physical interaction. Playing, meeting with other kids outside their neighborhood. Something a screen can't do. Regardless of anecdotic comments of random, anonymous slashdotters.
Without the maths, the defence is "I actually did stop briefly, but your view was obscured by another car". I would hope that in the interests of justice the simple version would also lead to an acquittal, the judge realising that if the police couldn't see the car at the time there is reasonable doubt. I expect it was more of a case of "wer'e not going to pay for a mathematician to support the prosecution on a trivial case like this.
In the UAE, all stop signs are treated like yield signs by the drivers... but there are not really 4 way intersections an when there are, they are in construction zones with no traffic volume - it's like a dangerous 4 way yeild and the intersection gets closed until they put up traffic signals. I don't think the accident rate at stop signs are any higher here than in North America, but I'd love to see some real data.
120 characters ought to be enough for anyone
In the UK, at least, stop signs are incredibly rare. (I live in a major city, and can only think of one, which is on private land not the main road system.) On the other hand, give-way signs (either triangles next to the road, or double-dashed-lines on the ground) are incredibly common; I think those are probably the equivalent of US yield signs, although I'm not sure how direct it is.
And 4-way stops are unheard of; in the UK, if something like that were needed, they'd put a mini-roundabout there instead.
(1)DOCOMEFROM!2~.2'~#1WHILE:1<-"'?.1$.2'~'"':1/.1$.2'~#0"$#65535'"$"'"'&.1$.2'~'#0$#65535'"$#0'~#32767$#1"
If you go up to a stop/give way sign at a fairly high speed and brake heavily at the last second, you're an arsehole. What people do that fail to realise is that they make people on the road they're joining or turning into nervous as hell. They've no idea if you're a late braker or if you're going to pull out in front of them and potentially cause an accident.
If he did drive his car as in that graph, I'd hate to be a passenger in his car with those g-forces. Heck even if he took twice as long to slow as in those graphs it would be pretty unpleasant if he did that every time he stopped. Besides which most cars can only manage ~-0.8gs and that's being done by professional drivers in ideal conditions with no regard for tire life. I suspect if you stretched out the graph for a more realistic acceleration of -0.5gs it wouldn't look more damning than supporting of his argument.
In the UK all STOP signs are yeild signs, and you can fail your driving test for stopping unnecessarily. UK red lights are the other extreme (there is no 'right on red' allowance), if it's red, you shouldn't pass it except in an emergency.
WTF. That's not true. STOP means stop in the UK. GIVE WAY means yeild.
We'd never have "right on red", we drive on the wrong side of the street over here. Some lights have a left turn filter light (green left arrow that comes on while the main lights are still red).
Sigs. We don't need no steenking sigs.
I.E. traffic tickets generate revenue for the police
And this I think is the biggest problem. It creates a conflict of interest. In my area in Pennsylvania, local cops have been setting up ENRADD devices, which are only legal in PA. These devices are basically two beams of light that your car breaks as it moves through, and based on the timing and the known distance of the two beams, they can tell how fast you were going.
Except that they can't. If the beams are set up in such a way that the first beam triggers on your wheel, and the second beam triggers on your bumper, it can greatly over-estimate your speed (they are only 3 feet apart, it can easily clock you at 60mph while you're doing 30mph). Also, being just beams of light, even if installed correctly, a car coming the opposite direction can be the trigger of the second beam, so that can also produce unreliable results.
They set these things up on the busiest roads, virtually guaranteeing they have a nonstop stream of revenue. They line up 5 or 6 patrol cars in a row to pick up people, and they have the tickets pre-filled out as much as possible (including date, officer name, location, direction of travel, and even the fine and ticketed speed). The only thing left to fill in is to copy over the drivers license and car info. They only ticket you for going 5 MPH over, then write in "Actual speed X MPH" according to presumably what the ENRADD device told them. This way there's no points on the ticket, and most people realize that paying a ~ $110 fine is a better use of their time than fighting the ticket in court (I for example am an hourly contractor, it would cost me more in lost productivity than simply driving to the court house, nevermind however many hours I might be inside).
I mentioned that they have 5 or 6 patrol cars issuing tickets - these are township level cops, in some townships that might be the entire police force, spending an entire day individually earning the police force a few thousand bucks per hour. The tickets are pre-dated, so you know they are going to issue every ticket in that stack before going home. The roads are the busiest roads, so they have the best chance of creating false positive readings.
It's absolutely unconscionable that the police force gets to keep the proceeds of their activity. It creates a mercenary mindset. These cops are going to be incentivized not to increase traffic safety, but to earn a profit. Ticket proceeds should be given to state social programs rather than benefit those who are tasked with enforcing the tickets. Likewise seized property and other form of proceed from police activity should not benefit the police force.
Slay a dragon... over lunch!
WTF. That's not true. STOP means stop in the UK. GIVE WAY means yeild.
True, but actual STOP signs are very rare - I can't think of one that I pass regularly (other than on barriers and roadworks where they mean "stop and stay stopped until someone takes the stop sign away"). In the US, equal-priority "4-way stop" junctions are ubiquitous where, in the UK, we'd probably have a roundabout, traffic lights or give one road priority and use "Give Way" signs on the others.
We'd never have "right on red", we drive on the wrong side of the street over here.
I think that maybe, just maybe, the GP actually knew this and thought the audience would be able to translate it into "left-on-red" for UK use. AFAIK in the US it is based on the 37th amendment to the constitution which states that every American citizen shall have the right to scare the bejezus out of Limey tourists on crosswalks (who were looking the wrong way anyway).
In a survey of 100 programmers, 111111 thought that duck-typing was a good idea.
In PA if the posted speed limit is LESS than 55 MPH you cannot be cited UNLESS your speed was AT LEAST 10mph over the POSTED limit.
Title 75 - VEHICLES
Chapter 33 - Rules of the Road in General
3368 - Speed timing devices.
(4) No person may be convicted upon evidence obtained
through the use of devices authorized by paragraphs (2) and
(3) unless the speed recorded is six or more miles per hour
in excess of the legal speed limit. Furthermore, no person
may be convicted upon evidence obtained through the use of
devices authorized by paragraph (3) in an area where the
legal speed limit is less than 55 miles per hour if the speed
recorded is less than ten miles per hour in excess of the
legal speed limit.
If they ticket you for 5mph over then FIGHT IT.
Oh, and KNOW THE LAW. LEO is last person on earth who you should place any trust in.
Laws of Physics were declared unconstitutional by their state supreme court, along with evolution.
I don't know how it works in the 1000s of other cities and towns, but in mine THE POLICE DON'T KEEP THE MONEY. The money from ticket revenues goes to the general fund, just like money from other enforcement fines [health dept, building dept, parking enforcement] and other fees [permits, parking, building, etc] and other revenues [property tax, state aid, grants, etc].
I've been involved in local politics for some time, and I've never heard of a police department that kept the ticket revenue. If you know of one, please provide a citation.
Support a few technologists in Washington.
They serve more arrest warrants than anybody else and are the ones most likely to be visible to the population at large.
That is only because the police refuse to put any real resources into investigating *real* crimes like theft and vandalism. If the police took all of their traffic cops and put them on investigating property crimes instead, there would be a huge decrease in property crimes and we could start putting people in jail for real crimes for a change. How many times have you heard about a friend whos home or car got broken into? These criminals are not brain surgeons. They leave tremendous amounts of evidence behind, but the police dont even bother to collect any of it, much less investigate. My car was broken into a few years back, and the perpetrator left about 50 full prints behind. The cops wouldn't even show up (took a statement over the phone!). My wife was a criminal justice student at the time and had access to a fingerprinting lab. After lifting about 3 dozen prints, a friend of ours in the DCJS ran the prints through the database (only a minor violation...), and sure enough out pops a guy we've never met. Had three prior convictions for drug related charges, and one grand theft! This was strike four, and the guy would have been off the streets for good, but the cops failed completely.
Long Story short, the police need to stop worrying about traffic tickets so much, and start doing actual criminal investigations. At any given point, how many cops are tied up in speeding traps? How many real crimes could be solved if those cops were to spend their time investigating instead of sitting in a parked car...
-=Geoskd
I wish I had a good sig, but all the good ones are copyrighted
At the risk of stating the obvious, if the defendant in this case had had a black box installed that could provide an accurate indication of his actions, he wouldn't have needed all that science (which of course many defendants who were similarly innocent could not have produced) to refute the officer's mistaken allegation.
Observations and facts are fine, it's one-sided observations and asymmetric access to analytic resources that tend to screw things up.
If you disagree, post your argument. (-1, Overrated) isn't your personal censorship tool for views you don't like.
While I agree with you about inappropriate policing priorities, I have to say I find your actions in abusing privileged access to a database to be more offensive than those of the person who broke into your car. Your friend at the DCJS who committed that "minor violation" should have been fired and prosecuted. The fact that you were right in the end does not justify the means, and we must never allow that kind of rationalisation to excuse abuse of public trust when officials have access to sensitive personal information.
If you disagree, post your argument. (-1, Overrated) isn't your personal censorship tool for views you don't like.