We’ve all seen it in our rearview mirrors….the hood of the car behind you. Why the hood? Because the damn car is too close to see the headlights. Quick brake check? Gets your point across, but not at all safe (or smart). The smart move is simply moving over and letting the impatient assclown go along his/her way.

I’m not saying that I miss my Dad’s old ’65 GMC pickup when I had a tailgater. That thing was like a friggin’ tank and it would be no problem to remind tailgaters that their proffered method of following me wasn’t the best way. No, no…to say that would be irresponsible and incredibly foolish.

About a year ago, my department issued the motors lidars with the DBC (Distance Between Cars) function. The DBC works by shooting both vehicles either as they approach (front bumpers) or as they pass (rear bumpers). The lidar calculates the speed of both vehicles, distances from the operator’s location, the distance between the cars (in both time and feet), and the time between both shots.

Human perception/reaction time has long been understood to be 1.5 seconds. Folks that are way smarter than me and probably have more initials behind their names and degrees on their walls conducted enough experiments, studies, and scientific type stuff to determine that time. What does that mean in layman’s terms? It takes .75 seconds for your average human to perceive, in this example, what the driver ahead of you is doing, and an additional .75 seconds to safely react to it. That totals 1.5 seconds from start to finish.

Consequently, when I shoot two vehicles with the DBC function and I get a digital readout with the time between the two cars. That is to say, it calculates how quickly one car will pass the same point the car in front of it just passed. I feel perfectly justified in stopping and citing anything less than one second. More often than not, though, I give an additional benefit of the doubt of another .1 second. Generous, no?

Here’s the part where the judge in my jurisdiction seems to get stuck on. Let’s say the speed limit is 45 mph. I see two cars and the second is too close to the first. I shoot both cars and get a display of .88 seconds and a distance of 53′. The second vehicle is not violating the basic speed law at 43 mph. Or is he? CVC 22350 requires drivers to “have due regard for the traffic upon the highway”. If the vehicle in front of the tailgater is too close for safety, doesn’t that violate 22350? Maybe, but CVC 21703 is more specific with regard to tailgating, “The driver of a motor vehicle shall not follow another vehicle more closely than is reasonable and prudent, having due regard for the speed of such vehicle and the traffic upon, and the condition of, the roadway.”

It seems because the speed and distance in the aforementioned example is what it is, the judge takes exception to the rule. Allow me to explain further…

43 mph correlates to about 63 fps (feet per second). In 1.5 seconds, the vehicle will travel about 94.5 feet. If the distance between the cars is 53′, it is nearly physiologically impossible for a human to avoid a collision if the driver in front aggressively brakes for any reason at that speed.

It’s an anomaly for the judge to take exception to tailgating. I’ve testified to 21703 a couple dozen times and I’ve written quite a few that never went to trial. In my opinion, it’s a fantastic cite and helps reduce collisions if people are more aware of how close they are traveling behind the car in front of them. So many of our rear-end collisions cite speeding as the primary collision factor when in fact tailgating is more likely the culprit. Unfortunately, witnesses are scarce and speeding is easier to prove than tailgating without corroboration from a witness or involved party.

I’ll keep writing them. If the judge sees fit to dismiss the occasional violation, it’s no skin of my nose. As far as I’m concerned, I’m making the streets safer by writing this particular violation. So many people simply don’t realize how close they actually are to the car in front of them. And it’s awful damn hard to argue with the lidar.

Please note: I reserve the right to delete comments that are offensive or off-topic. Snark is encouraged. Being a prat is not.

24 thoughts on “Tailgaters

  1. When I used to drive the freeway, tailgaters were my worst fear. Our freeway is only 2 lanes so often there was no where to go (both lanes being busy). They were also usually very aggressive. Very scary. One a**ho*e actually ran me off the highway. It happened to my daughter too.

  2. Grace, $20 says you were constantly tailgated and cut off because you were driving like a jackass, not because other drviers are too aggressive for no good reason. Since you said 'used to drive the freeway,' I would like to thank you on behalf of all CA motorists for finally selling your car or just staying off the freeways.

    As for MCs argument, there are so many holes in it, it's not even funny!

    43 mph correlates to about 63 fps (feet per second). In 1.5 seconds, the vehicle will travel about 94.5 feet. If the distance between the cars is 53', it is nearly physiologically impossible for a human to avoid a collision if the driver in front aggressively brakes for any reason at that speed.

    The main problem with your argument is that it fails to consider the fact that the vehicle in front of you will still keep moving during braking rather than instantly turn into an immovable brick wall the moment the driver touches the brakes. In other words, if V2 is 53' behind V1 when V1 applies the brakes, the gap between the vehicles will NOT close at the rate of 94.5fps unless the driver of V1 is super-drunk and crashes into a stopped cement mixer truck without ever touching the brakes.

    Another completely wrong assumption in your argument is that the standard reaction time is the minimum amount of time between the illumination of brake lights on V1 and V2 starting to brake.

    Most of the time, it's very easy to see traffic conditions ahead of the vehicle you're following, including the rear lights of the vehicle directly ahead of the one you are following. If the car ahead of V1 starts to brake hard and the driver of V2 sees it at the exact same time the driver of V1 does, both V1 and V2 will start their braking at the same time and 53' will be perfectly sufficient to avoid the collision between V1 and V2.

    So, if you pay attention to traffic around you, it's easy to anticipate and react to such situations far faster than 1.5 seconds after the other car begins an all out panic stop.

  3. That made my brain hurt. I like to dumb it down a bit by counting "one mississippi, two mississippi" and so forth.

  4. HonkingAntelope, what you're forgetting is that sometimes you can't see that squirrel Mother Theresa is braking for ahead of you. So yes, MOST of the time if you are paying attention, you can avoid these things and it's okay to tail gate. MOST of the time, I can drive 35 mph through downtown and not hit anything. But the 25 mph speed limit is not made for "MOST of the time." It's made for every once in a while when a little girl slips away from her mother leaving the library and darts into the street. Laws aren't made for "MOST of the time." They're made for the freak occurrances that you in your infinite wisdom didn't see coming. (Never thought I'd be defending a cop.)

  5. Oh, you're also forgetting that it's never okay to almost kill someone, no matter how frustrated you might be with her driving.

  6. So, HonkingAntelope, tailgaters are justified if they are tailgating a person who is "driving like a jackass"? Attitudes like this are what get people killed. Tailgating is unsafe no matter what. Since you are so keen on making assumptions and wagers, $100 says you drive like an aggressive a-hole.

    I wish that police would write tickets for tailgating and other aggressive driving infractions more often. These actions probably cause more wrecks than we think.

  7. Oh Jeez Louis….play nice in the sandbox, HA. How can you say Grace was driving like a jackass? She was simply saying there are lots of aggressive drivers out there.

    MC was just giving us a scenario. Tailgating is an issue he covers quite well – it's easy to armchair quarterback with different angles to the arguement, but don't rip him a new a–hole while ur at it.

  8. Ok, wayyyy too much math involved in that post.

    Way to jump on Grace for making a simple comment, HA.

  9. Hey MC, I got ticketed for that, and there was no argument from me, since the cite was secondary to my rear-ending the vehicle in front of me! In my defense, I was distracted by a really pretty field of sunflowers. Stupid sunflowers! Thanks for keeping the highways and by-ways of Cali safe.

  10. Another whole in this argument, besides the one pointed out by Honking Antelope is that the distance between cars at a given momemt does not tell you anything about tailgating.

    For example, if Grace is going at constant 40 mph on a 45 mph road, then a car approaching Grace from the rear will come closer to her rear bumper temporarily, as it slows down to accommodate Grace's extra cautious driver style, than what would be a safe following distance at a constant 40 mph. But, in most case, the braking driver behind Grace will either pass or brake enough to generate a safe gap behind Grace to follow her at her preferred speed of constant 40.

    Now LIDAR makes could take care of this problem by making the LIDAR not indicate a "tailgating" unless it occurs continuously for, say, 10 seconds. LIDAR makers could have programmed such a requirement into the tailgating detection feature of their LIDAR units, but they don't and this is a serious, and obvious, design flaw. This is because LIDAR makers don't care about tailgating. They care about revenue, because revenue generation is what sells more LIDAR units (and other fun accessories). So they leave an obvious design flaw in the tailgating feature of their product, and IYGSYDI exploits this flaw on a regular basis and most judges don't care, but one does. Good for the one who does!

    In my experience, the worst tailgaters (and I mean real tailgating now, not LIDAR style fake tailgating) are police cars. The cars least patient with pedestrians in crosswalks when making right on red are also police cars. If IYGSYDI is really serious about the tailgating problem, then maybe he can ticket a marked unit some time and see how that goes. Til then, he's jes talkin' the tak, but he ain't walkin' the walk.

  11. Collisions don't occur over a 10 second period. They occur in tenths of seconds. Your desire to measure something like tailgating over a 10 second period is both unrealistic and foolhardy.

    Also, the lidar will not allow the DBC function to shoot both cars if there is more than a 5 mph difference between the two vehicles (specifically to alleviate any 'slingshot' effect or a quickly accelerating following vehicle or quickly braking leading vehicle) as that would lead to a much briefer and not as accurate a picture of the violation.

    The lidar also requires the operator to shoot both vehicles within 3 seconds. If it takes longer than that to shoot both vehicles, then there is obviously no violation.

    With regard to the judge who "cares"…he's found just about all the other similar violators guilty. Sometimes an anomaly gets in. It's the nature of the beast. Shame that he cares about the safety of the streets as much as I do, huh?

  12. One other thing…

    As with speeding, I observe and visually estimate before using the lidar. Let me be clear, there is no legal requirement stating I have to justify my observations/estimations with any equipment. After observing/estimating tens of thousands of cars over the last four or five years (and confirming them with equipment), my skills in that vein are sharp.

    If I see a car that tailgates, but realizes their mistake and backs off, I don't stop them…because they don't deserve it. If the tailgating continues over a significant distance, they get stopped because, well, you know.

  13. When being tailgated, I just press the pedal enough to light up the brake lights, but not actually cause my vehicle to slow sharply, or really even impact my speed much at all. It's safe and usually effective. Many people seem to tailgate and not even realize it, and this method helps to make them aware.

    Just drive to the conditions folks. I back extra far off of a car if I can see that it's tailgating the car in front of it. Why? Because other drivers are creating conditions that are unsafe, thus requiring slower speed and greater following distance.

    I personally think that the extra 3-5 minutes on average that it may cost me in my commute time to drive safely is worth the reasonable boost in the safety of me, my family, my property, and that of the drivers around me.

    If you're frustrated by that type of driving, you deserve to be. I'm not trying to frustrate you, but I'm not apologetic about it.

  14. Tailgaters here are issued cites for "following to closely". The main time these are given is at a MVC, to the car that rear-ended another.

    As for the tailgaters, I hate them, especially when on 2 wheels. It's in the motorcycle knowledge test for the license to slow down for tailgaters to encourage them to go around you.

    Recently, my dad was headed to work and a teen girl was chatting away on her phone and tailgating him. He punched thew gas and she stayed with him, so he took the turn onto the expressway at 50 (he has a vehicle that can handle that) and when she tried to follow, nearly lost control and ran into the guardrail. She didn't wreck, but it was proof that she was too HUA to realize what she was doing.

  15. The lidar also requires the operator to shoot both vehicles within 3 seconds. If it takes longer than that to shoot both vehicles, then there is obviously no violation.

    It sounds like the LIDAR only says what the distance is at one, single instant in time. That doesn't tell much of anything about tailgating. For example, if some idiot sees a police car and slams on the brakes, the cars behind him are going to bunch up for a few seconds. That doesn't make everybody a tailgater.

    Sounds like LIDAR doesn't give much of any useful info about tailgating. It is still the policeman who decides the important question, which is: are the cars temporarily close due to driving conditions, or is one car really riding another's tail? That was the key question before LIDAR and it is just as key now. LIDAR doesn't prove tailgating at all. Just as much as before it is up to the policeman to be honest and not write bogus tailgating tickets. LIDAR changes nothing in this regard.

  16. At risk of poisoning the well for the fellow pro per defendants in CA, let me throw in a few cents' worth on the DBC procedure.

    What is the magnification and the field of view on your LIDAR's aiming scope, if any? Also, when you transitioned your LIDAR's aiming reticule to measure the following vehicle's speed/distance, did you continuously monitor the speed of the vehicle ahead of the following vehicle while measuring the speed of V2?

    The biggest legal issue I've noticed in your description is that you have no way of measuring the speed of V1 aside from corner-of-the-eye-through-the-scope visual estimation once you transition the LIDAR reticule from V1 speed to V2 (with V1's apparent speed being distorted by the scope magnification, and corroborated by the defense counsel first asking if you maintained your visual focus on the LIDAR reticule + V2's license plate as you measured the speed of V2 using the LIDAR).

    Most high-performance cars can easily gain 10-30mph and good distance in 3 seconds if the driver floors the gas. My car can do 0-60 in 5.4 seconds, and If I was the cited driver, I would testilie to the effect of:

    "I was traveling behind V1 at a similar speed when V1 suddenly slammed on the brakes for no apparent reason (and if the issue came up on the redirect, i'd ask if it's normal for speeders to reflexively slam on the brakes when they spot a police vehicle). I gently applied the brakes on my car due to sufficient distance between myself and V1, and another car following me so closely I could not even see its headlights through my rearview mirror. As I was slowly closing the distance between V1 and myself, V1 suddenly accelerated and began to pull away. I released my brakes, and, a minute later, I was pulled over by M/C and cited for VC21703, even though I felt that there was no risk of collision at any time during this incident.


  17. Wow…never thought this would inspire so much debate. At any rate…

    There is no magnification on my lidar's scope. The average time it takes to shoot both vehicles is round about 1 second. The adjustment in speed by V1 in that space of time is negligible. Again, if there are any anomalies (sudden deceleration, stop/go traffic, etc.) I typically don't cite for 21703. I cite for 21703 when the violation is obvious.

    The lidar does in fact measure the speed of both vehicles. No, I can't measure them at the same time, but again, since I shoot both vehicles in about 1 second, I don't believe the alleged difference in speed would make any difference.

    With regard to "high performance vehicles"…this isn't a lap track it's your every day roadway with some traffic on it. In all my years of enforcement, I've never seen any vehicle's speed change +/- 30 mph (or even 15 mph) in 3 seconds. Again, this is any everyday roadway.

    Finally, although I've addressed it in a previous comment, I wouldn't cite someone for tailgating if the vehicle in front "slammed on the brakes". If anything, given the circumstance, the slammer may be entitled to an unsafe stop citation.

  18. Finally, although I've addressed it in a previous comment, I wouldn't cite someone for tailgating if the vehicle in front "slammed on the brakes". If anything, given the circumstance, the slammer may be entitled to an unsafe stop citation.

    That is fine, but you are missing the point, which is that LIDAR doesn't prove anything as far as tailgating goes. It all comes down to whether the policeman is honest (as you say you are) or dishonest (like bad policemen are).

  19. We'll have to agree to disagree. In my opinion, the Lidar basically provides a snapshot or moment in time and provides information regarding speeds and distances (in both feet and seconds) and I feel more than comfortable taking that information and testifying as to why a given distance at a given speed is unsafe.

  20. In half your posts on this thread you say that you can tell tailgating based only knowing spacing and speeds at a single instant in time, and in the other half of your posts you admit that there is more to it than that and you have to watch the cars over time to see whether the too-close spacing is temporary or permanent.

    I think you are more correct in the posts where you admit that tailgating is maintaining a too-close spacing persistently and not temporarily.

    My main point in posting on this thread is that they can probably design a LIDAR that measures whether the spacing stays to close over an appropriate interval of time. Judges should wait for that new kind of LIDAR before accepting LIDAR evidence on tailgating. In the meantime, judges should decide tailgating cases based on the testimony of the policeman and the defendant and the person allegedly being tailgated (if in evidence), just like the judges always have for years and years now.

    LIDAR should not be used as a stealthy way of changing the definition of what "tailgating" really is.

  21. You what my pet peeve is? When I'm leaving room between my front bumper and the car in front of me, and some idiot thinks it's the place he needs to be and so causes me to tailgate by cutting in front of me. Then I back off,and it happens all over again, and again and again….sigh.

  22. I've been rear ended twice, both times because I had to avoid a situation in front of me. The first situation: pedestrians suddenly deciding to cross in front of me, the second a car in front of me doing a panic stop. I could avoid these situations because I don't drive up someone's tailpipe. Tailgaters are my #1 Pet Peeve because their aggressive driving endangers everyone else on the road. Keep zapping 'em, keep fining 'em, maybe they will change their habits if it hurts them hard enough in the wallet.

  23. You know Motor, I try to drive with what I believe to be a safe amount of space between my vehicle and others' vehicles. What I find is that no matter how much space I leave, some moron jumps in the space. It could be 2 car lengths or 5 car lengths and somebody feels the need to fill the empty space. It's freaking annoying.

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