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Math Transportation Science

The Laws of Physics Trump Traffic Laws 378

Posted by Soulskill
from the in-this-house-we-obey-the-laws-of-thermodynamics dept.
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."
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The Laws of Physics Trump Traffic Laws

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  • 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.
  • by PRMan (959735) on Saturday April 14, 2012 @11:01PM (#39690717)

    In other words, the cop was claiming that my woefully underpowered car from the 70s was accelerating like a modern Porsche.

    I had a similar situation where I was stopped going 80 on the freeway. The problem was my Saturn couldn't have accelerated to 80 from the ramp. I presented the mathematical formula to the judge and the officer, showing that there was no way my car could do what he was claiming. They didn't care. I got the ticket anyway.

  • by Anonymous Coward on Saturday April 14, 2012 @11:09PM (#39690741)

    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.

  • Two counter examples (Score:3, Interesting)

    by tipo159 (1151047) on Saturday April 14, 2012 @11:19PM (#39690777)

    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.

  • by Cimexus (1355033) on Saturday April 14, 2012 @11:20PM (#39690785)

    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.

  • by mysidia (191772) on Saturday April 14, 2012 @11:38PM (#39690861)

    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.

    What should happen is the county should be required to fairly compensate you for your lost time, driving costs for both trips, and inconvenience (Including the inconvenience of having been pulled over), if you are found not guilty.

    A portion of that should come from the officer's salary / annual bonus. Maybe then they would be more careful about making sure a crime was actually committed before stopping a vehicle and issuing a ticket.

  • by Grayhand (2610049) on Sunday April 15, 2012 @12:05AM (#39690987)
    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.
  • JUDGE by SKYPE (Score:2, Interesting)

    by cheekyboy (598084) on Sunday April 15, 2012 @12:17AM (#39691037) Homepage Journal

    I want to see a future, where you immediately, go online with the cop to a live judge via skype on the ipad, so that there and then can decide if the cop is wrong, then the cop is to pay a fine.

    I tell you, the whole justice system , plus the education system and the medical system needs a complete overhaul redesign and be 100% wireless.

    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?

  • Me Too! (Score:4, Interesting)

    by Tourney3p0 (772619) on Sunday April 15, 2012 @12:35AM (#39691091)
    Something similar happened to me my freshman year of college. I had an 8am EF exam the following day, so I was up late studying for it. Around 1am or so, my calculator batteries died. I was just about ready to go to bed after studying one or two more problems, so I was quite unhappy about having to go out to get new batteries.

    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".

  • by Anonymous Coward on Sunday April 15, 2012 @12:51AM (#39691151)

    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.

  • Re:JUDGE by SKYPE (Score:4, Interesting)

    by hjf (703092) on Sunday April 15, 2012 @01:37AM (#39691291) Homepage

    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?

    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.

  • by Belial6 (794905) on Sunday April 15, 2012 @01:40AM (#39691303)
    Yep. I had a pal I was with that was ticketed for not stopping at a stop sign. When asked how he could have seen my pal's car given that there was a field between them where the weeds were 1 1/2 feet higher than the height of my friends car, the cop's answer was "I don't know, but i did." The ticket was upheld, as that was apparently good enough for the judge.
  • by Soul-Burn666 (574119) on Sunday April 15, 2012 @03:00AM (#39691511) Journal

    A good friend of mine was pulled over by a cop who claimed he was speeding, driving over 100kph in a 50kph zone.
    This was a *really* old and ran down car so the friend proposed that if the cop can reach 100kph in his car, he'll agree with the ticket.
    After about 2 minutes of struggling to go over 30kph, with the cop swearing heavily at the car, he gave up on the ticket.

  • by shutdown -p now (807394) on Sunday April 15, 2012 @03:55AM (#39691619) Journal

    And that the officer totally missed the difference in position between a car that sails through an intersection as opposed to one that both decelerates to a full stop and accelerates fully up to speed over a period of about 3 seconds

    His point is that there was no way to not miss the position, because the car that sailed in front was much bigger than his, and had completely occluded his car for a "significant" time (i.e. long enough to make it possible to stop-then-start and end up with the same speed as if he'd slowly cruised through).

  • Yeah... (Score:5, Interesting)

    by abigsmurf (919188) on Sunday April 15, 2012 @05:03AM (#39691809)
    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.
  • by nahdude812 (88157) * on Sunday April 15, 2012 @05:19AM (#39691871) Homepage

    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.

  • by Anonymous Coward on Sunday April 15, 2012 @07:10AM (#39692179)

    But since it went against the scientific consensus of the time, and wasn't peer-reviewed, I'm assuming you still don't believe a word of it?

    At least that's what you do if the topic is catastrophic anthropogenic global warming.

  • by Anonymous Brave Guy (457657) on Sunday April 15, 2012 @08:47AM (#39692707)

    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.

  • by wolfgang_spangler (40539) on Sunday April 15, 2012 @10:24AM (#39693309) Homepage

    I tried to use math to defend myself recently when ticketed for using a cel phone in a school zone. As an aside, I was using it legally (hands free) and picked it up after I exited the school zone, the officer said, "you picked it up about 5 feet before the end of the zone."

    It was a very, very interesting experience and I pretty much learned the point you just made AC. At the end of the day, in which I defended myself with math/physics the judge said, "I feel like I just had a college physics class. You know, there are two school zones on that street. You may have been in the zone, you may not have. I don't care, you have no business being on your phone on that street. You are free to appeal my decision.

    The fine was an annoyance (like 150) but I found it a very interesting experience in how small suburbs within cities make money and how a person going in there to defend themselves has basically no chance.

  • Re:Actually.. (Score:4, Interesting)

    by DigiShaman (671371) on Sunday April 15, 2012 @11:38AM (#39693813) Homepage

    Try a maglev train. Once I boarded one, I walked over to place my bag in the designated holding area near the doors. There were no windows in my direct view, so I kept on sorting my stuff without distraction. As I was walking down the isle to my seat, I was taken back at the fact we were already moving at 90 kph. Not knowing when movement actually started was a bit unnerving and cool as hell at the same time.

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