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  1. #1

    Default Speeding - GPS vs. LIDAR

    I received a speeding ticket while traveling north on I-90 in Massachusetts. The officer said I was doing 85mph in a 65mph zone. According to the ticket, the officer used LIDAR. Iím guessing now, but the last time I received a ticket of any sort was 25 years Ė Iím not the habitual offender. After reading events surrounding my ticket, I hope someone has a suggesting as to how to defend myself.

    I was travelling in the left hand lane going the speed of traffic. Having never been to the Boston area (Marlborough), I was using a GPS for navigation (I live in New Jersey). As I went over an overpass (route 135, Wood Street), the GPS alerted me I was 1 mile away from my exit (11A). The 11A exit sign was at the bottom of the overpass. At this time, I was attempting to move into the far most right hand lane, which is when I first saw the officer. He was just pulling onto I-90 and we were both competing for the middle lane. When the officer pulled me over, I was 100 yards from the exit.

    The officer notified me I was doing 85mph in a 65mph zone and asked for my license, registration, and insurance. When he went back to his car, I looked at the maximum speed my GPS recorded for the entire trip (over 5 hours of driving), which was 77.8mph. He then returned and handed me a ticket which stated my speed was recorded at a distance of 856.3ft by LIDAR. I never showed the officer the GPS and just said ďthank you.Ē When the officer and I pulled away, we were so close to the exit, we could not reach high speed before the exit itself, where the officer turned around just in front of the toll booth.

    I know GPS units are inherently inaccurate, but only to a point. The day was clear and I was on an open highway; no overhead trees or tunnels were in the area. In doing some reading, my GPS (Garmin NUVI 350) samples my speed every second and is accurate to 0.5meters per second RMS. That being said, it would be impossible for me to accelerate from and possible 77mph to 85mph and then decelerate back to 77mph without my GPS recording a higher speed.

    I normally travel at 74 to 75mph and almost always use cruise. I can easily understand how 77mph would be recorded as my maximum speed. Almost always, I come across someone who is driving the same speed as I am, and I would tap the accelerator to speed up and get past the person (e.g. increase speed 2 to 3 mph for a brief period of time, then remove my foot from the accelerator so the car returns to its set speed.

    Aside from the large speed disparity between the maximum speed recorded by my GPS as compared to the LIDARís reading, I was easily within a mile of the exit. I could not have been targeted any farther than a mile as there is an overpass. I saw the officer pulling onto the road after the overpass, but before the exit. Being within a mile, or more likely a 1/2 mile from my exit, it is hard for me to accept I was doing 85mph on a highway in which I have never travelled, while trying to get off. As I said before, we were both jockeying for the middle lane just before I was pulled over.

    If I was written up for 75mph in a 65mph zone, I would have never thought twice. In fact, I believe that is the speed I was traveling at, exactly 10mph under what the ticket was written for. Because I was going with the speed of traffic does not exonerate me from exceeding the posted speed limit; however, Iím out of state 1/2 mile from my exit, traveling at a speed that is contradictory to the maximum speed recorded by my GPS. Something sounds fishy. Anyone have any suggestions? Massachusetts refuses to accept an affidavit stating that I was travelling at 75mph Ė yes, Iím admitting I was breaking law. Yet, what I was ticketed for is just flat out wrong.

  2. #2
    Newcomer
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    Houston, tx
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    Default Re: Speeding - GPS vs. LIDAR

    I to almost always use my GPS for speed monitoring because my steering wheel is almost always in the way. I have noticed that GPS is very accurate except during turns. Although you were not turning you state that you were changing lanes and that could have caused an error. You may have speed up to change lanes and at that time the GPS could have not been accurate. For example, have you noticed that when your off the highway on the feeder roads the GPS still thinks your on the highway? On the same regards the GPS thinks that your still going straight but yet your not actually going straight your going diagonal. Thus the GPS thinks your going less distance over time but actually your going father just the GPS doesn't realize it because its not straight. A better example is when your on a curved highway the GPS will always say your going slower then actual speed! (try it)

  3. #3

    Default Re: Speeding - GPS vs. LIDAR

    Possible, but even changing lanes on a highway, yo are still essentially going straight. And remember, 77.8mph was a maximum speed for the trip, I really do not know how fast I was going at the time. I speculate 75mph, just because it is habit. But for your theory to pan out, while changing lanes, I would have had to accelerate to 85mph in preparation to get off at the next exit, which is only 1/2 mile away. I believe what you say is true; I just do not think it applies in my situation.

  4. #4
    Radar Fanatic
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    Sep 2007
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    Default Re: Speeding - GPS vs. LIDAR

    Bad news is you are probably screwed. Lidar is fast. I also run MPH on my Gps. Good luck.

  5. #5
    Speed Demon
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    Jun 2009
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    People's Republic of California - OC
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    Default Re: Speeding - GPS vs. LIDAR

    Storie like this make me consider upgrading my dash cam to a GPS dash cam with speed overlay. Then again, in may case it would probably not be a good idea to have my speed documented on video most of the time...

    I'd see how much of a difference there is in the fine and whether it is worth your time to fight the extra 8 MPH if you got lucky and the judge accepted your GPS data as proof you did not exceed 78 MPH.

  6. #6

    Default Re: Speeding - GPS vs. LIDAR

    The fine is $200. Two points will be transferred to NJ no matter what, but Jersey doesn't surcharge until 6 pointes are amassed. There will be no surcharge imposed by my insurance company because I have not received a ticket or been in an accident for over 20+ years. If it was reduced to 75mph, the ticket would be $100, which is what I was seeking - I was speeding, just not to the extent as documented on the ticket. It will cost me easily $150 just to get there (from NJ to Mass) and should I win, I would only save $50; but really, the money is no longer the issue with me. It is the fact that the ticket is flat out wrong. I do not believe it to be an accident the more I read on this forum. Right now, I have such a bad taste in my mouth against officers, its unreal - all because someone needs to have a certain ticket count? They do not accept affidavits to a lesser charge with me presenting evidence against myself? This whole thing is a giant scam - and I appear to be the loser (or maybe, a victim). I know I should just calm down, but the more I think about this, the more it infuriates me.
    Last edited by B_Regal78; 04-14-2012 at 08:47 AM.

  7. #7
    Speed Demon
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    Jun 2009
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    People's Republic of California - OC
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    Default Re: Speeding - GPS vs. LIDAR

    There are a lot of good cops but also a lot of them are whores for the government which is pimping them to generate revenue. The vast majority of tickets are to generate revenue and not to for activities which were truly unsafe. I really hate that.

    I'd say pay the ticket and then order a laser jammer. On a couple of occasions I have had the great pleasure of seeing the perplexed look on the face of an officer looking at his laser gun that failed to clock me in time.

    To me speeding is a game that keeps me alert and entertained on otherwise long boring drives. Eventually LEO will get one on you but with a good RD, laser jammer, and sensible driving techniques the odds are greatly in your favor to win almost every time.
    Last edited by 904nm; 04-14-2012 at 10:05 AM.

  8. #8
    Speed Demon
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    Apr 2012
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    Amerika
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    Default Re: Speeding - GPS vs. LIDAR

    Yeah,it's the same for me,it's a game to keep me alert on long run 300+ mi.I got popped & was in court.The young lady ahead of me was charged for 76mph in a 65 on the Mass Pike...judge found her guilty.The Statie musta been having a bad day,I woulda given her a warning & she was good looking,too.In Mass. don't go over 74 unless you've got jammer.Be careful of I/O radar too.
    Good luck.

  9. #9
    Good Citizen
    Join Date
    Feb 2009
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    197

    Default Re: Speeding - GPS vs. LIDAR

    Unknown to many drivers, a number of GPS units store your "maximum speed" since you last reset the devices maximum speed log.
    For example, the Garmin Nuvi 1450 stores it in your route information data (you may have to scroll down to see it). You can check it to see if you ever went 85mph since its last reset. It won't help you in court, but it may give you some peace of mind that you did in fact go that speed at some point in time.

  10. #10
    Newcomer
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    Feb 2008
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    Louisville, Kentucky
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    41

    Default Re: Speeding - GPS vs. LIDAR

    Somethings not right here - Lidar can only be used from a stationary position...

 

 

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