From: Toby on
On Sun, 11 Jul 2010 21:07:22 +1000, John Tserkezis wrote:

> Toby wrote:
>> Who says the software developer would need to be asked?
>> The point is - nobody knows, one way or the other.
>> .... right?
>> If you want to play, get it straight that SOFTWARE written by person or
>> persons unknown is regarded by GovCo in these parts as inviolate - declared
>> to be that way, in fact. And you and I can't get to see it to decide - one
>> way or another, no matter what.
> I don't think this is the case.
> From the few people I've spoken to, the quoted numbers are close enough
> to spot on to be spot on. The reported speed is the speed you were
> actually travelling at, give or take the quoted tolerance of the test
> gear (few percent? It's quite tight).
> There's none of this "quoted as 71 so you were actually doing 86
> bullshit. It doesn't work like that.
> However, as it turns it there doesn't *need* to be any software
> fiddling - the system is rigged to not make it worth your while to fight it.
> An example in point with Victoria's reputed 3Km/h tolerance, you CAN
> indeed have the fine removed if you can prove your speed readout is
> within specification, but off by enough to warrant your innocent over
> speeding (because you followed your speedo in good faith).
> However, it's the "if you can prove" bit that's going to let you down.
> You have every legal right to have your speedo tested and submit the
> results to court, but that's going to cost you. Arguably more than the
> fine in question.
> In other words, you have lots of legal avenues to choose from and ALL
> of them are going to cost you. I'm guessing purely coincidently, the
> fine would be the least of the costs in this instance.

No need to guess.
Whatever the fine, there are those that would make damm sure the costs were
Unless you're running a cab - a different ball-game there. Wonder whether
the cabbies are still keeping a speshul set of loaner tyres/rims for the
meter testing:-)
Caveat Lector
From: D Walford on
On 11/07/2010 6:47 PM, Doug Jewell wrote:
> the fonz wrote:
>> On Jul 11, 2:11 pm, Doug Jewell <a...(a)> wrote:
>>> Former
>>> boss who is still a good friend, showed me a camera ticket
>>> his wife got recently for 63 in a 60 zone.
>> that means she was probably doing 65 or 66 before the tolerance was
>> applied.
> The Qld ones don't subtract a tolerance. From what I've seen in other
> states, if the camera records 66 they book you for 63 as you imply. In
> QLD the photo has the radar readout in the top right corner, and you are
> booked for what it reads. The radar is considered infallible. I'm yet to
> hear of a ticket for less than 3 over, but prior to them reducing the
> tolerance i hadn't seen any for less than 10% over.
I'd like to see the result of such a fine being challenged in court,
many such cases with very low tolerances have been contested and won in
Vic courts.

From: D Walford on
On 11/07/2010 8:14 PM, the fonz wrote:

> again, you don't need keep your speed within 5 km/h. personally, i
> find it easy to stay within +/- 2km/h most of the time, with the
> occasional slight deviation. the odds of passing through a speed
> camera at that same moment when i deviated by more than 2 km/h are
> narrow - i'd suggest most people being caught were speeding for much
> more than just that short moment.

You are assuming that your speedo is accurate, most speedo's I've
checked with several very accurate GPS's read high and many are up to
10kph out meaning that when your speedo is indicating 100 you are doing
closer to 90-95 so its no wonder you never get a speeding fine, maybe
you should be fined for obstructing traffic or careless driving for
spending too much time concentrating on your speed instead of actually

From: John_H on
Toby wrote:
>There's also the gag where speedo error is allowable in manufacture (or
>compliance, for that matter) - has that changed?
>Last I heard - and I can't check the ADR's because I WON'T pay for
>something I've already paid for) - it was +4 -0. That -0 is interesting.
>I'm betting old but not quite bald tyres give the +4.

You'd lose that bet! :)

The rolling circumference of a tyre lies below the tread (the tread
compresses across the contact patch) and isn't significantly altered
by tread wear. Think of it as a belt that alters it's shape as it
rotates. If you cut across the tread and lay it out flat what will
the length, which corresponds to the rolling circumference, be?

The steel belts are what determines the rolling circumference and the
bits on either side either stretch or compress to match.

I've been monitoring the odometer on my Subie with the GPS trip
computer (Garmin) since it was new. It's now down to the wear
indicators and the odometer (and hence the speedo reading) hasn't
varied by more than half a percent which is around what the variation
(measurement accuracy) has always been. It's virtually impossible to
read a speedo within half a percent.

From memory the odometer error on that particular car reads +1.5% and
the speedo is around +5%. Both are constant... ie they don't change
with tread wear.

>I notice however, that the speedo watchers who don't have GPS are at least
>4Kn'Hr slower than I am through the 100-110 traps and most everywhere else.
>'Cause i drive on GPS speed in those risk-prone areas. You know - the
>deadly pieces of road with the known accident history, bad sight-lines
>rough surfaces etc - just like out brand new Gateway sections with the
>increased (breach of promise by Govco) toll.

John H
From: John_H on
the fonz wrote:
>On Jul 11, 6:49�pm, John_H <john4...(a)> wrote:
>> >that means she was probably doing 65 or 66 before the tolerance was
>> >applied.
>> 63 would've been the indicated speed. �If the tolerance is 2kph in a
>> 60 zone it means you don't get booked for a reading of 62... the 2kph
>> doesn't get deducted from the reading.
>> The accuracy of the measurement is a separate issue to the tolerance
>> on the posted limit, and would typically be much smaller.
>i agree but i think we're saying the same thing.
>i'm sure i've received fines where they take 2 km/h off the reading
>for measurement error. that's still a tolerance - for measurement
>error, but there's an additional tolerance for general leniency. if
>that's 3 km/h, then you add the two together and would be able to be
>measured at 65 km/h without being fined. (which could be a true 63-67
>if the radar is +/- 2km/h accuracy).

The accuracy of the measuring equipment (when correctly used) ought be
considerably better than that, and certainly within +/- 1kph. I'm
basing that on experience with both Doppler radar and DGPS. Even
autonomous GPS (eg sat nav) is better than +/-1 at a *steady speed*...
lag errors on a changing speed are due to the relatively slow sampling
times (when compared to commercial equipment). In any case the
detection equipment will hold the highest reading obtained (which
doesn't constitute an error).

Tolerances of 10% and greater have long been the norm. In Q they vary
according to location (which we're not supposed to know). There are
certainly places where you're very unlikely to be booked at the first
level of fine (up to 12kph over the limit) by either a camera or
mobile radar. That's to say if the reading's 113 you might be booked
for 113, but you're unlikely to be booked for 112.

I've only had two speeding fines in the last thirty years but both got
the speed as near as damnit to spot on (I knew my speedo error in both

Other states might do it differently (ie deduct a tolerance from the
reading) but I'd seriously doubt it in the absence of any concrete

John H
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