ExpertLaw.com Forums

Florida Traffic Laws Pertaining to Radar

Printable View

  • 08-29-2013, 07:47 PM
    MZ3
    Florida Traffic Laws Pertaining to Radar
    My question involves traffic court in the State of: FLORIDA

    I have a few questions pertaining to RADAR - its discrepancies and a few other various questions.

    I have dash cam footage of an officer citing a driver and I would like to know if the fact that the officer was behind a stationary object at roughly a 30 degree angle to the road, if said stationary object would adversely affect the RADAR's reading, and if so, if that would be admissible and have any baring on the proceedings.

    Also, I would like to know if there's an easy way to calculate a vehicle's speed within the same dash cam footage. It's not obviously apparent that the vehicle in question is passing or even approaching faster than the other surrounding vehicles. I can even watch the vehicle in question pass by and still be at the same pace as other vehicles in front and behind.

    The vehicle was claimed to have been going 70MPH, which is roughly 102FPS, I did a rough count after seeing the vehicle in question round the object in front of the patrol vehicle till the time the vehicle in question approached and left frame; it took roughly ~7 seconds. So theoretically the vehicle should've traveled 718ft in the ~7 seconds. By looking on a Google Maps representation of the exact area of the citation using the video footage, that distance isn't even possibly visible on the video.

    Are there any good references for using against such a case such as the apparent objects obstructing the view of the officer and the apparent time it would take to travel that far but would not be possible to do so in the position spotted until the position leaving the camera frame?
  • 08-29-2013, 08:41 PM
    jk
    Re: Florida Traffic Laws Pertaining to Radar
    the angle you are speaking of (cosine error) always benefits the driver. If you know anything about trigonometry, you will know that since the radar measures speed by using the doppler effect action on the radio waves, the radar will perceive the car moving slower when measured from an angle since the distance difference from the radar gun is less for any given amount of time than if it was moving directly towards or away from the radar source.

    the stationary object would not increase the speed if it affected the reading at all. In fact, it would do just the opposite since there would be no difference in distance from the radar unit. If that was somehow calculated in the speed computation, it would lower the average speed the radar unit calculated.

    It used to be possible to actually increase the speed measured by utilizing the windshield wipers or blower motor in the cop car.



    as to determining the speed from a video: possible but not very accurately. You would have to know, accurately the frame rate of the camera and be able to determine distance traveled over a given number of frames. Unless you were directly to the side of the vehicle being recorded, there could be no fixed objects in a position to be able to accurately determine the distance traveled.
  • 08-30-2013, 06:26 PM
    MZ3
    Re: Florida Traffic Laws Pertaining to Radar
    Yeah I wasn't referring to the cosine error, just trying to give an idea of the scenario since you can't see the video.

    The camera's recording at 29.97FPS. I was working backwards on the video. Allegedly the vehicle was traveling 70MPH, 102.6 Feet per second, so I used a point of reference in the video to calculate the vehicle in question's estimated speed from rounding the object until going out of frame. the distance traveled is still unknown but i can assume if it took ~7 seconds to come around the object and then next to the patrol car and out of frame then when i initially saw the vehicle round the object it had to be 718ft away from where it left the frame and where it originally rounded the object.

    And then using Google Earth, I could fairly accurately measure 718ft on the exact stretch of road where the patrol car was sitting using points of reference like telephone poles, center median turning areas, etc

    - - - Updated - - -

    I'm going to use my measuring wheel and do some triangulation to prove that the distance traveled in the video is what it seems visually, which is NOT the claimed speed.
  • 09-01-2013, 02:23 AM
    That Guy
    Re: Florida Traffic Laws Pertaining to Radar
    I hate to be the thorn in the side of your enthusiastic bubble, but my guess is that you can put your creative mind to some better use of its resources... In this case, you're spinning your wheels... Figuratively, that is...

    Quote:

    Quoting MZ3
    View Post
    I have dash cam footage of an officer citing a driver and I would like to know if the fact that the officer was behind a stationary object at roughly a 30 degree angle to the road, if said stationary object would adversely affect the RADAR's reading, and if so, if that would be admissible and have any baring on the proceedings.

    How do you know if it was the front facing Radar antenna that was active at the time this reading was obtained? What if that officer had had his rear facing antenna set to measuring speeds?

    And speaking of cosine effect, if you've looked at a full angular range of calculations of speed differentials versus the angle a measurement is taken at, you'll note that there typically are little to no significant differences up until you exceed 25 or 30 degrees with the parallel. So to account for an officer's location on the right side of a multiple lane freeway, and to accommodate for and cover that entire width, either or both front/rear facing Radar antennae are typically installed at an angle of 20 degrees or so from parallel.

    And typically, any officer who is Radar trained and certified is also certified in visual estimate, and his/her testimony will include a visual estimate the always seems to end up within +/- 5 mph of the Radar reading testimony that follows. So how do you refute that?

    Who's camera was it that was recording and how do you prove that no one manipulated the recording/playback speed? And when it comes to your measurements using your measuring wheel, when was the last time that was calibrated and how do you authenticate your measurements with any degree of accuracy; an accuracy that you are purporting should rival (or exceed) that of Radar, a technology that has been in use and has been deemed to be sufficiently accurate to convict people of criminal charges in many states ever since the mid 1950s?

    Google Maps imaging, even Google earth can skew distances by as much as +/-10% if not more. So while those measurements might be sufficient to estimate an ETA at Grandma's for Sunday supper, you're not getting anywhere in court claiming an accurate speed measurement over ~700 feet of space. At least not more accurate than the officer's visual estimate which was confirmed via Radar.
  • 09-01-2013, 07:41 AM
    Jack Jackson
    Re: Florida Traffic Laws Pertaining to Radar
    Quote:

    Quoting That Guy
    View Post

    And typically, any officer who is Radar trained and certified is also certified in visual estimate, and his/her testimony will include a visual estimate the always seems to end up within +/- 5 mph of the Radar reading testimony that follows. So how do you refute that?

    r.

    Its the visual estimate that can be used to address the charge as well.

    You can ask: how long was the measurement period during your visual estimation time period?
    Then ask: what was the distance that the vehicle traveled during this time period ?

    If the cop cannot testify to a single value, ask for a range of the time and distance.

    Then pull out a calculator and figure out the min/max speed that he visually measured.
    You need not ask him further questions about his visual speed measurement but highlight to the judge what the slowest value was MPH and maybe highest (if it calc. out to 300 MPH haha).

    Most cops have simple HS educations and I love it when they try to calculate in their head an answer to the second question after they already answered the first knowing that one is looking to examine his visual estimate skills. And their math skills s-u-c-k ... if they do try to do the calc. in their heads then you'll always get outrageous results.

    If the lowest value is well within the speed limit and the cop testified that his skills are +/- 5 MPH then his visual estimate, as calculated from HIS testimony then this is enough to ask for a motion to acquit after the state rests.
  • 09-01-2013, 08:02 AM
    cdwjava
    Re: Florida Traffic Laws Pertaining to Radar
    Quote:

    Quoting Jack Jackson
    View Post
    Most cops have simple HS educations

    Well ... not quite. (Sorry, I can't let this claim stand as "fact")

    Keep in mind that some states require 60 units or an AA/AS degree for entry, and some departments require that much - or more. In CA the police academy is approximately 25 semester units (or more) on its own. Once upon a time a number of agencies in CA and elsewhere used to REQUIRE a BA/BS just to apply. But, as the years have gone on, the number of agencies requiring 4-year degrees has dwindled to about 1 percent of the total.

    According to the FBI in a report released this year some 88 percent of officers have "two year degrees" or the equivalent and 48 percent had 4 year degrees (this is 20 percent higher than the national average). More than half achieved additional college education after beginning their career (likely as a means of promotion) which is approximately 15 percent higher than the general workforce who claim to have taken courses at college or to improve job skills.

    There are a host of reports and studies out there related to this issue, so, try not to claim that "most" (i.e. one more than half) of all officers possess nothing more than a "simple" high school education. That might be locally true where YOU live, but it's not true on the whole.
  • 09-01-2013, 10:36 AM
    jk
    Re: Florida Traffic Laws Pertaining to Radar
    Dang Carl, that's actually quite impressive.


    Its also funny as all heck to see jacks ambiguous statements, which he seems to post everywhere with absolutely no support, soundly trumped with honest and supportable facts.
  • 09-01-2013, 11:57 AM
    MZ3
    Re: Florida Traffic Laws Pertaining to Radar
    Quote:

    Quoting That Guy
    View Post
    I hate to be the thorn in the side of your enthusiastic bubble, but my guess is that you can put your creative mind to some better use of its resources... In this case, you're spinning your wheels... Figuratively, that is...



    How do you know if it was the front facing Radar antenna that was active at the time this reading was obtained? What if that officer had had his rear facing antenna set to measuring speeds?

    And speaking of cosine effect, if you've looked at a full angular range of calculations of speed differentials versus the angle a measurement is taken at, you'll note that there typically are little to no significant differences up until you exceed 25 or 30 degrees with the parallel. So to account for an officer's location on the right side of a multiple lane freeway, and to accommodate for and cover that entire width, either or both front/rear facing Radar antennae are typically installed at an angle of 20 degrees or so from parallel.

    And typically, any officer who is Radar trained and certified is also certified in visual estimate, and his/her testimony will include a visual estimate the always seems to end up within +/- 5 mph of the Radar reading testimony that follows. So how do you refute that?

    Who's camera was it that was recording and how do you prove that no one manipulated the recording/playback speed? And when it comes to your measurements using your measuring wheel, when was the last time that was calibrated and how do you authenticate your measurements with any degree of accuracy; an accuracy that you are purporting should rival (or exceed) that of Radar, a technology that has been in use and has been deemed to be sufficiently accurate to convict people of criminal charges in many states ever since the mid 1950s?

    Google Maps imaging, even Google earth can skew distances by as much as +/-10% if not more. So while those measurements might be sufficient to estimate an ETA at Grandma's for Sunday supper, you're not getting anywhere in court claiming an accurate speed measurement over ~700 feet of space. At least not more accurate than the officer's visual estimate which was confirmed via Radar.

    I'm not, nor have I ever tried, to use or quote the cosine error effect. You still have to use angles (which I can't represent in text as well as I could in a photo) to calculate distance and to give a picture of the scene.)

    I used both Google Earth's Ruler tool and my own measuring wheel and they were EXTREMELY accurate between each other - enough that it wouldn't matter for speeds; the only thing needed is solid points of reference.

    The documents I also received in my documents request has the vehicle he used and that it only had 1 RADAR antenna, so he can't be using a rear running RADAR antenna when only 1 is present - in the front. Besides, that doesn't make any sense, if the officer was using a rear antenna on me, you wouldn't see me visually in front of the vehicle as I stated. You would see me going away from the vehicle, which I didn't state anywhere.

    The camera was the officer's camera, in his car, on his dash. The recording came from them, on DVD. I don't care if RADAR has been in use and been deemed sufficiently accurate. It's also had sufficient evidence that it isn't accurate nor precise; just like LIDAR.

    No Google Maps\Google Earth doesn't skew up to +\- 10%, I went out and did the measurements myself, and verified the distances. The distance covered is not "~700 feet of space" (which by the way would be cubic feet, since you're referring to 'space'), the distance is 429.85ft. It will certainly be more accurate than a visual estimation and equal or better than RADAR.

    Bottom line, I did it myself with triangulation, a measuring wheel, Google Earth, and photos taken myself standing in the exact position the camera was recording from (within the patrol vehicle), and using the dash cam recording from the supplied DVD.

    Thanks to everyone else that responded, minus 'That Guy', as he just spewed out non-sense whilst *attempting* to play the obvious devil's advocate. :)
  • 09-01-2013, 07:18 PM
    That Guy
    Re: Florida Traffic Laws Pertaining to Radar
    Quote:

    Quoting MZ3
    View Post
    … Bottom line, I did it myself with triangulation, a measuring wheel, Google Earth, and photos taken myself standing in the exact position the camera was recording from (within the patrol vehicle), and using the dash cam recording from the supplied DVD.

    The fact that you did it yourself is nothing to brag about. Instead, it is the basis why nothing you plan on presenting is of any evidentiary value to the court. You could even hire an expert witness to make the presentation on your behalf and still, it’s a known fact that a paid expert witness would say any thing you paid him to say.

    The video itself, and while it can be authenticated if and only if presented by the prosecution, was recorded with the intent of using it as some sort of reference to the events that might occur immediately before and during a traffic stop, but not to measure your speed. There is other evidence that is specifically designed to establish your speed, Radar evidence. And that will be used accordingly. Whether you like it or not!

    If a prosecuting attorney is present at your trial, s/he will have a field day with your “evidence”, and s/he’ll tear your entire case into shreds while you‘re standing there remembering these words. Even without a prosecuting attorney, the court will place little to no value to your evidence. Simply because what took you days to photograph, measure, calculate and triangulate, was done ten times over by the same Radar unit you’re attempting to undermine.

    The Radar used was more than likely tested and is on an approved list. The officer operating it is likely to be trained and certified in its use, and he will testify accordingly that he tested its accuracy before and after his shift; he will likely provide documentary evidence from a known, well established and certified facility attesting that the unit used that day was maintained and found to be in perfect working order within the previous 6 months before your citation was issued as required by Florida law.

    And how did you arrive at your results? Oh wait… It doesn’t matter. None of it is admissible!

    No matter how you calculate it: Inaccurate Distance / Inaccurate Time = Inaccurate Speed.

    To assume you are going to walk into court, put up a bunch of measurements on a board and have the court buy into your claims of accuracy, you’re only fooling yourself

    Quote:

    Quoting MZ3
    View Post
    Thanks to everyone else that responded, minus 'That Guy', as he just spewed out non-sense whilst *attempting* to play the obvious devil's advocate. :)

    For one, if you seriously thought that I expected a “thank you”, then you are still only fooling yourself!

    Two, you can look at my post as an attempt to help you refine your arguments (or, better yet, throw them away and try something different), or you can look at it the way you did, as an attempt by me to make you look like a fool when in fact, you had already done a mighty fine job of that long before I came to this thread.

    Three, what makes your assessment even worse is that I wasn't playing "devil's advocate", simply because what you're mistakenly seeing as "nonsense" is factual information as to why your plan for a defense is going to flop.... Sad for you!

    - - - Updated - - -

    Quote:

    Quoting Jack Jackson
    View Post
    Its the visual estimate that can be used to address the charge as well.

    No it is not... The visual estimate is not designed to establish or calculate a target speed. This is why it is always a precursor to a more accurate and (in spite of MZ3's questionable and pointless claims) more reliable methods of determining an actual estimate. Those methods being Radar or Lidar reading. The visual estimate is simply used as a means for the officer to establish some sort of reference to the vehicle that he determined to be the fastest at the time.

    Quote:

    Quoting Jack Jackson
    View Post
    You can ask: how long was the measurement period during your visual estimation time period?
    Then ask: what was the distance that the vehicle traveled during this time period ?

    If the cop cannot testify to a single value, ask for a range of the time and distance.

    Where do you come up with this crap? How do you even begin to establish that the officer has to monitor traffic, use Radar, have a stop-watch in his hand and pre-measure several distances on the roadway is pretty nonsensical of an assumption.

    Vascar and Robic which use timing over a certain distance to calculate speed are other speed detection methods used in some states, but the visual estimate plays just as basic a role in those methods as it does with electronic speed detection.
All times are GMT -7. The time now is 07:48 AM.
Powered by vBulletin® Version 4.2.4
Copyright © 2023 vBulletin Solutions, Inc. All rights reserved.
Copyright © 2004 - 2018 ExpertLaw.com, All Rights Reserved