85th Percentile Speed

My question involves a traffic ticket from the state of: California

I got a ticket for traveling 40 in a 30 (22350) running an errand a quarter mile from my office. I think I have a pretty strong case to beat it from several angles:
(1) Speed limit was not actually posted along on my route (nearest posting is a block away)
(1b) The surrounding area is 40mph except for the one block where I was pulled(!)
(2) No pedestrians present, clear day, light traffic, i.e. no danger to others ("reasonable and prudent")
(3) 85th percentile speed from traffic survey is 36
(4) Traffic survey recommends lower limit due to unusual conditions that describe other parts of the block

I plan to do a TWD and was hoping for some quick advice on phrasing and presentation:
For (1) I can print out a map, take photos, and show easily.
For (2) is there specific language or precedent I should reference in making my argument that my speed was reasonable given the conditions? Is it foolish to admit I was traveling 40mph in my TWD? Given (3) should I be arguing a couple mph margin of error here?
For (3) do I understand correctly that the speed limit is ordinarily at least the 85th percentile? Any precedent or info I can point to here?
For (4) I'm basically trying to argue that the city was lazy and applied the same limit to both sides of the 4-lane road (street is divided by a raised median) and the unusual conditions (backup during rush hour, lots of driveways) only apply to the other direction.

Thanks for your help all.

You can not ever use conditions as a reason to exceed the prima facie speed. Your only chance is to show the prima facie speed violates the speed trap law. However, it sounds like you don't have a chance. You were still violating the 85th percentile speed (by default it should have been posted at 35) and you'll have a hard time arguing that within the course of a block, if there are things that mandate a lower speed, that the lower speed isn't applicable to the whole block .

Of course, you need to make sure you're not talking a "local street" and electronic speed means were used. If the officer testifies other than prima facie speed issues for the basic speed violation, you'll likely lose as well.

Street is two lanes in each direction, so not local if I'm reading VC 40802 correctly. There is a raised median in between the two sides so no reason to apply the conditions on one side to the other unless you have to have the same speed limit in both directions for some reason?

Officer used radar. What is the arguable margin of error if I can establish that it's a speed trap and 85th percentile speed was 36? I can't even see my speedometer that closely - I was clocked at 40, but I could easily have been anywhere between 35-45. This seems a little egregious to me.

THere's no "margin of error." The 85th percentile rounded to multiple of 5 is 35. 40 is in excess of the prima facie limit even by your most lenient interpretation of the speed survey. In fact, it appears the posted 30 MPH is justified. You've not found anything exculpatory.

Thanks for your replies. I guess I'm not following how 30mph is justified if the 85th percentile speed is 36? Only 31% of cars in the survey were traveling 30 or below. What is the legal significance of the 85th percentile?

Does the fact that there was no posted sign on my route (other than 40mph on the next block, which is what I was relying on) not help exculpate?

As for margin of error I was hoping for opinions on what's degree of tolerance stands up in court. LIDAR isn't presumed to be 100% infallible - if for some reason someone were clocked at 1mph over the limit without any other factors involved, surely that would be easily argued down? How about 2 mph? What's the precedent here?

Finally, it sounds like under the speed trap law the prosecution needs to show that my speed was dangerous. You mentioned conditions are never a reason to exceed the prima facie speed, but don't conditions and lack of pedestrians play a role in determining whether or not the speed was dangerous?

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Quoting loudnotes

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Thanks for your replies. I guess I'm not following how 30mph is justified if the 85th percentile speed is 36? Only 31% of cars in the survey were traveling 30 or below. What is the legal significance of the 85th percentile?

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Absent modifying factors, 85th, rounded to the nearest 5, is presumed to be the safe speed. However, you already indicated there was information in the survey that allowed for a lower speed. Just because they were for some fragment of the block other than where you think you were cited, doesn't make the prima facie limit of 30 ungrounded.

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Does the fact that there was no posted sign on my route (other than 40mph on the next block, which is what I was relying on) not help exculpate?

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NO.

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As for margin of error I was hoping for opinions on what's degree of tolerance stands up in court. LIDAR isn't presumed to be 100% infallible - if for some reason someone were clocked at 1mph over the limit without any other factors involved, surely that would be easily argued down? How about 2 mph? What's the precedent here?

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There is no fixed percentage that applies to LIDAR. You won't find it. Besides, you were 33% faster than the prima facie limit as posted, and even 14% faster than the your ARGUED (but unsupported) prima facie speed. That's way more than 2% or even 5% of "margin of error."

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Finally, it sounds like under the speed trap law the prosecution needs to show that my speed was dangerous. You mentioned conditions are never a reason to exceed the prima facie speed, but don't conditions and lack of pedestrians play a role in determining whether or not the speed was dangerous?

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No they don't have to show any such thing. THey just have to show that the speed survey indicates that the prima facie speed is not LOWER than the survey would mandate. If you are going faster than the PRIMA FACIE speed, you are assumed to be unsafe. THat's what prima facie means in this case. If you were less than the prima facie speed, they'd have to show via conditions or whatever, that you exceeded whatever the safe speed is.

TG or one of the other California's can speak up, but given all you've said here, you've not got any thing exculpatory.

I think Ron pretty much covered it all... But there's still plenty to sayI'll reiterate some points...

The 85th %ile being 36mph, gets rounded to the nearest 5mph increment which is 35. I can't see the survey and am not going based upon your statement (which maybe a verbatim version of the engineer's but without seeing the entire document I am simply following along)... And the speed limit is justified at 30mph.

Speed trap defense is out....

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Quoting loudnotes

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(1b) The surrounding area is 40mph except for the one block where I was pulled(!)

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It is neither reasonable nor practical to set the speed limit for a single block to a lower speed. I have never seen a survey that only covers one block. While this might be one long ass block... The criteria is measured in miles, or half miles to be more accurate. The MUTCD recommends a minimum distance of of a 1/2 mile or more between the limits of the survey.

Whether speed limits around it are 40 or 70, it makes no difference... Different stretches of the same roadway often get surveyed separately -and although part of the engineers work is to coordinate adjacent segments together, a different speed in one segment foes not invalidate any others.

Conversely, the declared speed limit for the surveyed segment within the limits of the survey gets the same speed. You cannot simply opt to increase the speed limit on one block just to accommodate your defense.

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Quoting loudnotes

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Is it foolish to admit I was traveling 40mph in my TWD?

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The process a speed trap case goes through starts with the officer testifying to the contents of the survey, and how it justifies the speed limit, his training and certification, he'll describe the circumstances under which your speed was measured, and if the age of that survey is 5 years or less, then he would rest his case at that point. If it is 5 years or older then he also has to meet the provisions under VC 40802(c). The burden would then shift to you to prove that the speed he measured you driving at was safe and prudent under the conditions described at the time... Simply saying “I know I was safe” or “I know I wasn't going that fast” or “conditions were ABC, or D... And so typically, arguing it is not advisable ; and not only are you admitting it, but you are basing your defense upon that speed. There is no way or reason to deny it... More importantly than all of that is the fact that the meaning of California's speed trap laws, in cases where the speed limit is not justified, then regardless of your speed, there can be no conviction.

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Quoting loudnotes

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Given (3) should I be arguing a couple mph margin of error here?

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there is no margin of error. From a mathematical stand point, there are no elements that would suggest any sort of "margin of error". Some steps may do away with 2.5 mph for no reason other than to round it off to a number that is easily posted by the authority in charge and easily complied with by drivers.

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Quoting loudnotes

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For (3) do I understand correctly that the speed limit is ordinarily at least the 85th percentile?

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Actually, its the opposite.... Your description suggests the 85%ile speed is at the bottom of the group of speeds we are considering, when in fact it is the highest speed. But more than that, the 85th percentile speed is the highest speed at which the majority of motorist feel is the safest speed. And coincidentally, it is also the highest speed at which crash rates are the lowest on the majority of roadways.

In theory, the posted speed limit can, at most, be 2 mph higher than the 85th percentile. (Example, the 85th %ile is determined to be 33mph, and since it is preferable to post limits in 5mph increments, the first step would be change it to the nearest 5mph increment so that is can be posted (assuming that there aren't any factors that will contribute to it being lowered). In thas hypothetical, the posted speed limit will actually be 35mph.

Most surveys that I have seen, the posted speed ends up being anywhere between 7mph lower than the 85th percentile speed.

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Quoting loudnotes

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Street is two lanes in each direction, so not local if I'm reading VC 40802 correctly. There is a raised median in between the two sides so no reason to apply the conditions on one side to the other unless you have to have the same speed limit in both directions for some reason?

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Like I said above and in several other threads, I am not going to comment on the validity of any survey argument until I can see it, IF I get to see it. And in reality, I am not aware of anyone who has ever been able to convince the court of any substantial errors in engineering judgment, simply because more often than not, the person nitpicking, has never seen a survey before let alone put one together, and so the courts aren't particularly impressed by these sort of arguments.

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Quoting loudnotes

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Officer used radar. What is the arguable margin of error if I can establish that it's a speed trap and 85th percentile speed was 36? I can't even see my speedometer that closely - I was clocked at 40, but I could easily have been anywhere between 35-45. This seems a little egregious to me.

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What is egregious and why? You don't deny speeding, I don't know what you mean by “I can't see my speedometer that closely”, but again, the speed issue is a moot one simply because if this were not a speeding citation that is subject to the speed trap laws, then the mere fact that the officer will testify to a certain speed that he clocked you at, that is sufficient for a conviction. Add in the speed trap laws, and the speed issue remains the same. you suggest you could have been anywhere between 35 and 45 which averages at 40mph. You were cited for 40mph

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Quoting loudnotes

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Thanks for your replies. I guess I'm not following how 30mph is justified if the 85th percentile speed is 36? Only 31% of cars in the survey were traveling 30 or below. What is the legal significance of the 85th percentile?

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We can only go by what you posted, that the survey lists reasons as to why the speed was reduced to 30mph. I already described how did it get the re from 36mph?

But to further provide you with more references for the source of that info, vehicle code section 627, 40802 through 40808, as well as VC 22352 thru 22366 regulate what factors can be used when evaluating a survey and the California MUTCD expands upon those elements and lays out the procedures by which they are determined, considered or otherwise dismissed.

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Quoting loudnotes

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As for margin of error I was hoping for opinions on what's degree of tolerance stands up in court. LIDAR isn't presumed to be 100% infallible - if for some reason someone were clocked at 1mph over the limit without any other factors involved, surely that would be easily argued down? How about 2 mph? What's the precedent here?

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You are far from being a mere 1 or 2 mph over. So that is not even close to being the issue here. Fact is, “margin of error” is a specification cited by the manufacturer. And one which the law cares very little about. Specifically, for California speed trap cases, the requirement is that the device be calibrated once every three years as described under CVC 40802. Most agencies will calibrate twice as often as that (or every 18 months), some even three times as often (once a year) whereas the CHP is known to calibrate once every six months or so.

That, along with your 15moh over, and the calibration/accuracy/margin of error arguments you've been beating to death all became “non-issues”!

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Quoting loudnotes

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Finally, it sounds like under the speed trap law the prosecution needs to show that my speed was dangerous. You mentioned conditions are never a reason to exceed the prima facie speed, but don't conditions and lack of pedestrians play a role in determining whether or not the speed was dangerous?

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Yet another reason why you should post the survey for everyone to see. The prosecution does have the burden to prove the defendant's speed was “unsafe” for conditions IF the survey was conducted five or more years prior to the date of the citation. Otherwise, the have the burden to prove the speed limit is justified, testify to your alleged speed, and rest.... The burden then shifts to you to provide competent evidence as to why the court should consider that your speed did not violate the basic speed law (see CVC 22351(b).

There are several reason why most (if not ALL) people fail at being able to articulate why their speed was safe under conditions:

1) Per the MUTCD requirements, the survey, must be conducted under conditions that are described as clear weather, dry pavement /no rain, and amongst a variety of several other conditions, and since these three are the ones dealt with more often, they get all the focus.
2) The fact that most survey's provide for speed counts of 100 or more vehicles, the opinion of one driver (the defendant) that his speed (to use you as an example) being 10mph over what determined by experts (traffic engineers), is not likely to convince the most favorable of judges.

And yet while most people will still try (and we have had a few claim they succeeded), most would have been better off with a possible fine reduction that may have received at the arraignment had they simply plead guilty.

Thanks for replying, That Guy; this is helpful feedback. My use of phrases like "egregious" and "margin of error" refers to be pulled for driving 40 in a zone I thought had a speed limit of 40, and that in fact has an 85th percentile speed of 36. I was trying to find out whether establishing that the speed limit "should have been" 36 would then mean I was effectively ticketed for 4mph over, which I further hoped might be "close enough" that the radar could be called into question. I see I did not fully understand the speed trap law's application, but that's why I was asking. Thank you for explaining so cogently, even if there was a bit of the usual incredulity included!

It sounds like the only potentially winning argument (not opining on likelihood) would be to convince the judge that the 30 mph speed limit was invalid. You write: "in cases where the speed limit is not justified, then regardless of your speed, there can be no conviction." That is helpful as that is the argument I will focus on in my TWD; whether or not it succeeds we'll see.

Now, as for the traffic surveys, I'm linking to them and would appreciate your kind-hearted opinion. (It seems I am not allowed to upload attachments). The city provided me with a one-pager for each block. I don't mind sharing the location - I was traveling south on Camino Ramon towards Norris Canyon. The officer was here and I was pulled approximately here. Note that setting the speed limit lower than the 85th percentile on the subsequent block (to 40) was done explicitly, but on the block where I was cited there was no reference to the 85th percentile speed. While there are unusual factors "not apparent" described in the survey, my contention is that they are entirely on the other side of the street, across a median, and did not apply to my travel path.

Block where cited
Block where pulled

How many times do we have to say. The speed is rounded to the nearest multiple of 5. In the second section, 42 is rounded to 40. However, that zone is 100% immaterial to you. You weren't cited for that. The survey is meaningless.

You also appear to have lied to us. The section between Crow Canyon and North Canyon is clearly posted at 30. The survey (absent TG finding something untoward there) appears to justify the 30 mph limit even though the 85th pc is higher. It validly cites the large number of driveways, pedestrian traffic, and recent speed related accidents. All the jumping up and down and crying isn't going to change the fact you exceeded a legally posted prima facie speed limii.

Wow, such hostility on a free legal help forum really baffles me. I'm asking for help preparing my defense, not trying to mislead anyone. How did I lie to you? Perhaps I was unclear - there is no posted speed limit sign on the route I traveled (I entered Camino Ramon from the shopping center; subsequently I went back and checked and the only sign is right at the intersection with Crow Canyon). There is one for 40 mph on the next block, which is what I was relying on. I'm not making up the absence of a sign for kicks...but anyway you said that by your understanding of the law, it doesn't matter whether there's a sign for me to see or not. That's what I was asking.

My focus on the survey, then:
36 would be rounded to 35, not 30. The point here is whether 30 mph is justified (again, only a small minority of traffic goes this speed according to the survey).
The 40 zone is the same road on the next block. It had the same number of speed-related accidents. I thought the comparison might be useful.

Take a look at the Google Map if you like; there are not, in fact, a large number of driveways and pedestrians where I was cited. I'm asking how to make that case most effectively, and you may certainly point out that its impractical to separately survey different sections of the same block, point me to some legal reasoning that obligates a driver to consider the condition of the whole block, or otherwise point out flaws in the argument. But no need to get upset! I really appreciate your time and opinions, no matter how delivered.

I'm not hostile. I'm just tired of hearing you bring up the same INCORRECT point over and over even though both I and TG have told you that you are wrong a donzen times.

Good by. Have fun blowing your mind in court.

Sorry my questions bothered you, flyingron.

Anyone else have an opinion on the traffic surveys?