Speed sign obscured... mandatory loss of license

[Day]

From the point of a motorcyclist particularly it is useful to realise that the beam width is 3.5m at 1Km.

Thus at ~333m the beam width would be ~1.2m which generally easily exceeds the width of the bike. I haven't worked out at what distance the beam exactly matches the width of the bike yet... but it must be somewhat less than this.

Thus any vehicle travelling beside or behind you might be included in any speed measurement... depending on the exact orientation.

Nope because if there were two speeds being returned to the device it would cancel out and start a new reading when it was achieving one speed result. The radars didn't do this.

[turtle]

In the case of radar if two vehicles are in the same beam the stronger signal wins. Which one has the stronger signal? Who knows?

This is why when there are two vehicles in a speed camera picture the police are meant not to prosecute.

This goes double for when one vehicle is larger than the other... as the signal from the larger vehicle usually dominates.

The police argued that radar was infallible for ages too... it turned out not to be true. Is there any reason to suppose they're right this time as well?

Electronics are usually incredibly dumb.

Is there any reason to suppose they're as smart of the police claim they are? If they're using the same algorithm as radar (probably) then they have the same problem?

This is probably why (taken directly from the manual):

"The Pro-Lite has a maximum targeting distance of 457 metres and the Pro-Lite + has a
maximum targeting distance of 609 metres."

They've probably assumed a car rather than a motorbike as the vehicle in question.

From the point of a motorcyclist particularly it is useful to realise that the beam width is 3.5m at 1Km.

Thus at ~333m the beam width would be ~1.2m which generally easily exceeds the width of the bike. I haven't worked out at what distance the beam exactly matches the width of the bike yet... but it must be somewhat less than this.

Thus any vehicle travelling beside or behind you might be included in any speed measurement... depending on the exact orientation.

Nope because if there were two speeds being returned to the device it would cancel out and start a new reading when it was achieving one speed result. The radars didn't do this.

[laserguru]

Hi,

Thus at ~333m the beam width would be ~1.2m which generally easily exceeds the width of the bike. I haven't worked out at what distance the beam exactly matches the width of the bike yet... but it must be somewhat less than this.

Thus any vehicle travelling beside or behind you might be included in any speed measurement... depending on the exact orientation.

Radar devices have had the same problem although they suffer from much more spread than laser... so their problems are worst.

turtle,

you situation appears to be that a little knowledge has become a dangerous thing.

Radar and laser are 2 completely different technologies and you cannot simply compare them to each other. About the only thing in common with both in their operation is they both suffer from Cosine effect.

Your beam width analysis is flawed. Whilst a motorcycle may well be a narrow target and some elements of the laser pulse may pass to the side of the main target, since laser speed guns are a "first target" system, provided there is sufficient return energy from the front of the bike or the rider, this is the target they "lock" onto. Even if there was some amount of refelction from an adjacent target (and it would need to be very close), if the bike was in front, then the bike is the acquired target.

The laser pulses are far narrower as a "beam" than a radar signal and radar will pick up multiple targets in its (wider) beam, hence their ability to display fastest and strongest targets. For radar its all about a strong reflection back off the target surface. Traffic radar has little or no ability to determine distance (yeah, yeah I know about the MPH unit with ranging), whereas distance measurement is the fundamental way a traffic laser works so determining the closest target is simple for the police operator coupled with where he aimed the red dot.


I have had experience targeting very fast bikes wiht a laser some time ago at Phillip Island during World Superbikes and was comfortably able to hit bikes close to 300 kph and pick one out of a pack at will. Ranges were around 250 - 300m. Target was the riders leathers or helmet. Have also hit F1 cars over 300Kph and superkarts at 240+kph. Usually targeting riders/drivers helmets.

[laserguru]

Hi,

Does anyone know how to obtain the calibration procedure used to calibrate the laser gun?


These points are relevant to all such devices as everything loses accuracy over time and must be calibrated from time to time.

How do you know that "everything loses accuracy over time" ??

Speed lasers use a precise crystall-locked timing clock cpabale of measuring down to nano-seconds. IF this clock were to "drift" off and meaure an incorrect time, this would show up immediately in the daily range check where an inccorect distance would result (given the speed of Light remains a constant).

The whole "calibration" process whether a daily check, an annual Lab check or the ultimate National Measurement Labs check is all about checking the timing circuit. NMI uses their Atomic clock as the base check of time which is tied into the world standard of time held in Europe. Calibration checks of test equipment goes down to pico second levels.
Traveability of measurements of time is assured and well and truly defendable in court should it ever be called into question. In fact, the clocks do not deviate in their performance and cannot be"calibrated" like a radar can be tuned. Radars do in fact drift off frequency and need to be checked regulalry.

Remember, speed lasers measure TIME and CALCULATE speed. Laser derived Speed is simply a change of position over a known time. Whereas radar measures a change of frequency which it CORRELATES to a speed (thanks Dr. Doppler). Laser is a far, far more accurate and direct measurement of speed. Radar is a correlation.

Any other misconceptions you need cleared up ?

[turtle]

Everything loses accuracy over time otherwise it wouldn't be necessary to calibrate it? Crystals lose time otherwise watches wouldn't lose time either... and they most definitely do.

The whole point of obtaining the testing procedure is to find out what the callibration process is and how prone it is to error. As the police haven't provided it... or even been able to tell me now often it occurs it seems a reasonable point to check.

If you're correct then it's not a weak point in the procedure... but it would be helpful if we had the actual procedure as a tangible document always beats a friendly conversation in a forum.

Do you have the actual procedure?

I've never seen the daily calibration. How is it carried out? How do you standardise a distance?

Hi,

Does anyone know how to obtain the calibration procedure used to calibrate the laser gun?


These points are relevant to all such devices as everything loses accuracy over time and must be calibrated from time to time.

How do you know that "everything loses accuracy over time" ??

Speed lasers use a precise crystall-locked timing clock cpabale of measuring down to nano-seconds. IF this clock were to "drift" off and meaure an incorrect time, this would show up immediately in the daily range check where an inccorect distance would result (given the speed of Light remains a constant).

The whole "calibration" process whether a daily check, an annual Lab check or the ultimate National Measurement Labs check is all about checking the timing circuit. NMI uses their Atomic clock as the base check of time which is tied into the world standard of time held in Europe. Calibration checks of test equipment goes down to pico second levels.
Traveability of measurements of time is assured and well and truly defendable in court should it ever be called into question. In fact, the clocks do not deviate in their performance and cannot be"calibrated" like a radar can be tuned. Radars do in fact drift off frequency and need to be checked regulalry.

Remember, speed lasers measure TIME and CALCULATE speed. Laser derived Speed is simply a change of position over a known time. Whereas radar measures a change of frequency which it CORRELATES to a speed (thanks Dr. Doppler). Laser is a far, far more accurate and direct measurement of speed. Radar is a correlation.

Any other misconceptions you need cleared up ?

[laserguru]

I doubt anyone will give you a blow by blow description of the procedure that CHECKS calibration of speed lasers. Understand that all that is done by police tech labs and the NMI is a CHECK that the laser is perfroming correctly. They cannot make any changes to CALIBRATION. Only the factories can do this. Radars are different, the frequency can be adjusted.

Read the Australian Standard AS 4691 part 1 page 13 Appendix A for a general description of what is usually done for the annual Calibraiton check. It is reasonably well described there although a revision of this Standard is probably due since technology has advanced and the equipment now used is significantly improved since that was written. Part 2 describes the daily checks using known ranges.

Let me say that you are wasting your time going down this track as it is highly monitored and strictly controlled and there is no room to argue the process is flawed as it has been rigourouly examnined both here in Australia and by the leading test houses in the world who monitor police speed detection equipment.

Mr Hardy may well find a tabulation or transcription error in the various documents he may examine under discovery on a speed laser matter and this may cause grounds for a dismissal but since I know that both NMI and most Australian police tech depts use an automated (software controlled) method to generate test sheets, this is highly unlikely to have occurred.

Regarding a daily check, all ranges I know of are set out using a certified tape measure or by a licensed surveyor using a calibrated survey intsrument. bear in mind the range accuracy of the test only needs to fall within the stated range specifications of the speed laser device which can be from +/- 30 cm down to +/- 15 cm depening on which manufactures lasers is used.

[Hardy]

Mr Hardy may well find a tabulation or transcription error in the various documents he may examine under discovery on a speed laser matter and this may cause grounds for a dismissal but since I know that both NMI and most Australian police tech depts use an automated (software controlled) method to generate test sheets, this is highly unlikely to have occurred.

I have never heard of a defendant satisfying a court that a laser speed measuring device was not properly calibrated. It has been over a decade since any client of mine has tried doing that. I wouldn't waste my time bothering with such an approach but that doesn't mean people who have the time and skills shouldn't give it a go themselves. However, the last laser speeding case I contested I won because the police failed to prove that their laser speed measuring device was properly calibrated.

[turtle]

To challenge a calibration procedure it is necessary to know what it is.

How did you establish that the calibration hadn't been carried out properly? What should we be looking for?

There should be a written procedure somewhere... otherwise the calibration is then open to variation... and variation can result in errors.

The best such document would be from the labs doing the testing... as it would form the basis of any questions on how calibration was carried out.

General documents about testing procedure may not accurately reflect practice... so they may not be useful but I'll take a look if I can find them. Thank you for the exact reference.

So if anyone has the internal documents I'd be grateful.

NB. Calibration problems are not the basis of my defence... but we shouldn't let any potential defence fail simply for lack of knowledge. Doing a due diligence investigation seems only sensible.

Thanks for the information.

However, the last laser speeding case I contested I won because the police failed to prove that their laser speed measuring device was properly calibrated.

[laserguru]

I would suggest you submit an FOI request for the file of the particular laser used in your case which should give you a history of its annual checks and from those sheets, you can reasonably derive what tests were done. Again I think you will find nothing to argue about. I know just how seriously the techs take this job and most labs are now NATA certified for breath and speed and NATA accreditation requires a substantial amount of compliance and detailed precedural documentation. Good luck on challening any of this stuff.

Again you must realise the labs do NOT claibrate speed laser equipment. They only check it remains within the factory set tolerances and can accurately ca; No adutments are made. If a device falls outside tolerances it is sent for repair.

[turtle]

Went to court the other day and the magistrate accepted the argument that under S322 of the Road Rules the sign was not "clearly visible"... which means it was not visible from all positions on the road.

It helped that I had no demerit points on my license and only a 25 year old previous court case.

Thus the speed limit was ruled to be 70 Kms not 60 Kms.

This was the difference between keeping my license and losing it in this case.

Yes I did pay a fine... which was $600 (which is much more than it should normally be) but that was acceptable.

The whole point of the case was to present both the prosecution and the magistrate with an alternative which was a reasonable compromise.

The magistrates court often does not like technical arguments so I wasn't sure if they were going to sit still long enough for me to present my evidence. However the case did not take very long and I handed copies of all parts of my evidence to the magistrate (photo's, road rules, Vic Roads maintenance guidelines and even an overseas court case). This stuff definitely helped... as neither the prosecution not the magistrate seemed familiar with the point of law I was highlighting.


That of course meant the prosecution was not prepared to defend it successfully.

[Day]

Interesting. Congratulations on what appears to be a satisfactory result. Did you find that the active discussions on this site assisted you in preparing for your case and having answers prepared should hairy questions be asked?

Thanks for the update. Closure is always good.

Cheers.

[turtle]

...in the multitude of counsellors there is safety"

http://www.flickr.com/photos/rexness/4345226886/

Victorian Parliament vestibule.

The advice in the forum especially from you and Sean was appreciated.

The forum provided a good ground for organising the arguments that were presented in the case... and identifying what information should be researched or was irrelevant.

Thus when I went in to see Sean I already had a good idea of what to ask about and we spent our time constructively.

Sean was able to add further detail that it is hard to get just via a forum including the full extract of a UK case dealing with an obscured speed sign... which the magistrate did consider... and was undoubtedly one of the reasons he found in my favour.

The case went almost exactly to script... which was helpful.

I can post some more detail if necessary.

Thank you very much.

Interesting. Congratulations on what appears to be a satisfactory result. Did you find that the active discussions on this site assisted you in preparing for your case and having answers prepared should hairy questions be asked?

Thanks for the update. Closure is always good.

Cheers.

[turtle]

Wonder if this is a new initiative and if it had something to do with my obscured sign court case:

http://www.vicroads.vic.gov.au/Home/HaveYourSay/ContactUs/ReportATrafficSign.htm

I wrote a reasonably detailed letter (but only 2 pages) to Vic Roads prior to the case pointing out how the sign was obscured and listing other obscured signs at the same location.
It also included what could be done to make these signs more visible.

After the case I followed up with a letter that clarified the points further (court cases help you to highlight problems and solutions).

Since the court case Vic Roads have moved the offending sign to put it in front of the tree and put extra signs in places that are clearly visible.

They also moved a similar sign on the opposite side of the road which was also obscured by a tree. In total they did at least 6 bits of work.

I was a little surprised at exactly how long it took Vic Roads to do this though (over 6 months)... as usually Vic Roads is remarkably responsive to constructive feedback.
I wonder if they were holding back till the case went through? I was hoping to use any changes as further proof that the sign was not clearly visible.


PS. I did make the magistrate aware that I had written a letter to Vic Roads... for which he congratulated me.
That was unexpected as as far as I'm aware the letter had no legal bearing on the case... and I didn't tender it as evidence.

[Hardy]

They provide a phone number instead of an email address. Ever tried calling vicroads??
I've emailed them a couple of years ago to suggest they move an obscured signs and nothing ever happened.
Eventually someone cut half the branches off the tree to make the sign more visible.

[turtle]

I regularly call Vic Roads... usually about traffic sensors that don't detect bikes (ever been stuck at a light that doesn't change?)... and they usually have a crew out to fix it them within a week.
Fixing a sensor often requires cutting new loops in the road... so it's not a minor thing (but not horrendously expensive either).

I deal with them regularly and have found them overall to be the most responsive of all the government entities I deal with.

Vic Roads are expert managers of risk and have an appreciation of consequences that is unusual in a government entity... so if it's likely to get them sued, create a future liability or get the minister on their back they will do something about it.

Writing a letter setting out the problem is often a good way to get their attention... as then the problem is clearly documented and may be used against them in a court of law.

If you can figure out how to fix the problem even better... then they can't say they didn't understand.

I do most of this by email then you're not wasting time on the phone and everything is clearly documented.
Just ring them and find out who the responsible person is and then follow through with that person until the problem is resolved.

Their managers seem to keep an eye on things (unlike many government departments) so issues don't simply get ignored: try to avoid staff who don't action issues.

Vic Roads has a higher than average IQ for an organisation... and that probably helps get problems resolved rather than just shuffled around.

Vic Roads also seem to be the most open to constructive dialogue (although they will stone wall you on some issues). Mostly staff also have a good technical knowledge which makes such a dialogue possible.

Mostly it seems that the squeaky wheel does get the oil.

[turtle]

I don't know if it's just coincidence but Vic Roads is now calling for submissions to a Speed Review (focusing on signs)

<terms of reference>
VicRoads is now seeking submissions on the following topics:

Routes with large numbers of speed zone changes.

Opportunities to reduce the number of speed limit changes.

Aspects of School Speed Zones, including layout and location, times of operation and days of operation.

Strip shopping centre times.

Speed limits in town centres.

Use and application of advisory speed limits.

Minimum length of speed zones.

Consistency of speed limits under similar conditions.

Contact details. Submissions can be made by email or mail:

Email
speedreview@roads.vic.gov.au

Mail
Speed Limit Review
60 Denmark Street, Kew, 3101


Closing date:

The closing date for submissions is Tuesday 11 October 2011.

Terms of reference:

Download the Terms of Reference document [DOC, 28KB, 3pp]
http://www.vicroads.vic.gov.au/Home/Saf ... Review.htm



http://www.vicroads.vic.gov.au/Home/SafetyAndRules/SafetyIssues/Speed/Speed+Limit+Review.htm