Margin of error

cool65 · 31-08-2011, 11:02 PM

In the last month, I have had 2 separate infringements for speeding. (the first in 2 years).
Infringement 1 - a 50kph suburban street with stationary car with laser
no traffic in area. Detected 71kph, Alleged 69kph.
Infringement 2 - a 100kph freeway with motorcycle with radar moderate traffic in 3 lanes. Detected 127kph, Alleged 125kph.
I was heading north and there was a 15kph tailwind from ssw.

How can something as accurate as a laser pointed straight ahead, be of the same accuracy as the radar from behind and have the same difference between detected and alleged especially at 50kph higher reading?

Of course the 25kph in Victoria now means a months suspension which I cannot afford as I have bills / family etc.
Really do feel like fronting a magistrate in this case hoping for a 1kph drop so I can keep driving.
Has anyone argued something similar before a magistrate?

cool65 · 31-08-2011, 11:16 PM

can a mod please move to advice central

sudszy · 31-08-2011, 11:27 PM

Quote:

Originally Posted by cool65

I was heading north and there was a 15kph tailwind from ssw.

Im not sure why you've included this?

joolz · 01-09-2011, 12:30 AM

Quote:

Originally Posted by sudszy

Im not sure why you've included this?

Used less fuel for the speed travelling i guess.

Jack960 · 01-09-2011, 12:31 AM

You can appeal but to be honest I don't think it will get you very far. Most of the cameras I have seen use vectors to determine a speed. Vectors are extremely accurate, different speeds will not effect it. It doesnt allow for a % of in accuracy or exponential change as you go faster. As far as i know, there is just the 3kph allowance.

The only time you can argue with a laser speed detector that uses vectors is if the camera is not level with your vehicle. Say if the laser is shot off a highway ramp down at cars, this is not accurate. We worked it out in physics at uni a while back :P

And the wind also does not effect the read out.

ltd · 01-09-2011, 09:30 AM

Quote:

Originally Posted by joolz

Used less fuel for the speed travelling i guess.

If he was actually flying and had an indicated air speed of 100 and was heading south south west, he'd have a true air speed of 115 (measured over the ground). If he was heading North north east he'd be doing a TAS of 85. Any other direction would mean a coefficient of his 15km/h ssw tail wind.
Either way, as he was in a car directly connected to the road he's in trouble.

DBourne · 01-09-2011, 09:32 AM

Quote:

Originally Posted by ltd

If he was actually flying and had an indicated air speed of 100 and was heading south south west, he'd have a true air speed of 115 (measured over the ground). If he was heading North north east he'd be doing a TAS of 85. Any other direction would mean a coefficient of his 15km/h ssw tail wind.
Either way, as he was in a car directly connected to the road he's in trouble.

So he needed to find a jump, hit it at speed, then claim his TAS was lower than indicated?

ltd · 01-09-2011, 11:30 AM

Quote:

Originally Posted by SgtBourne

So he needed to find a jump, hit it at speed, then claim his TAS was lower than indicated?

Ha ha ha yeah exactly. I'm sure we could find a solicitor to represent him.

2011G6E · 01-09-2011, 12:08 PM

You can take the day off work and fight it if you like...but you've got a snowballs chance in hell of winning.

Don't you know that police speed detection devices are the only scientific measuring equipment that never makes an error or has any margin of plus or minus built into it? Hell, I've worked in labs with measuring equipment worth hundreds of thousands of dollars, but it still requires a set range of conditions before you can be assured of a reasonably accurate result...a set temperature in the room, a stable base, known variables of the thing you are testing, carefull controlled environmental conditions, etc.
But the magical radar and laser guns police use can just be held at arms length, rested on the baking hot roof of a car, used from a moving vehicle against another moving vehicle with other targets in the area and a constantly changing background and road surface, and in all sorts of weather, and they still always give a 100% accurate inarguable completely positive and spot on reading of a vehicles speed...absolutely amazing!

(/sarcasm)...

SlowF6 · 01-09-2011, 01:23 PM

Quote:

Originally Posted by 2011G6E

(/sarcasm)...

Loved your final couple of sentences mate

JC · 01-09-2011, 01:53 PM

By rights they can book you for the "detected" speed, but they knock off 2km/h as that is the "leeway" in Vic these days. Sometimes it will mean the difference between a large fine and a small fine, sometimes not.

So in a 60 zone, if you're doing 62, you will not be fined, but the speed is still recorded (I assume they are audited for how many detecteds vs how many notices issued, so the "alleged" is what they act on)

Dave3911 · 01-09-2011, 02:13 PM

Why are you guys talking about cameras here? The OP hasn't been done by a camera, he's been done by a police officer. Once with a stationary car with a handheld laser, the other on a motorcycle behind him using a moving mode radar. This is NOT a camera thread. It's all in the OP.

Quote:

Originally Posted by 2011G6E

You can take the day off work and fight it if you like...but you've got a snowballs chance in hell of winning.

Don't you know that police speed detection devices are the only scientific measuring equipment that never makes an error or has any margin of plus or minus built into it? Hell, I've worked in labs with measuring equipment worth hundreds of thousands of dollars, but it still requires a set range of conditions before you can be assured of a reasonably accurate result...a set temperature in the room, a stable base, known variables of the thing you are testing, carefull controlled environmental conditions, etc.
But the magical radar and laser guns police use can just be held at arms length, rested on the baking hot roof of a car, used from a moving vehicle against another moving vehicle with other targets in the area and a constantly changing background and road surface, and in all sorts of weather, and they still always give a 100% accurate inarguable completely positive and spot on reading of a vehicles speed...absolutely amazing!

(/sarcasm)...

I have to call you out on that..... the as per the very essence of this thread, the police apply a margin of error(its even in the thread title) of 2km/hr. By their own acknowledgement they are saying that it's not 100%. Lets not forget our legal system works on a system of reasonable doubt, not absolutes and 100%. There are convicted murderers and rapists sitting in jail cells right now who didn't do the crime, it's just a fact of life that we all have to deal with. If we had a legal system that only imposed punishment on those that we were "100%" about, then nobody would ever get punished for anything.

I also note that the OP doesn't at any point deny the offence.....do the crime, do the time.

burnz · 01-09-2011, 02:44 PM

Quote:

Originally Posted by Dave3911

Why are you guys talking about cameras here? The OP hasn't been done by a camera, he's been done by a police officer. Once with a stationary car with a handheld laser, the other on a motorcycle behind him using a moving mode radar. This is NOT a camera thread. It's all in the OP.

I have to call you out on that..... the as per the very essence of this thread, the police apply a margin of error(its even in the thread title) of 2km/hr. By their own acknowledgement they are saying that it's not 100%. Lets not forget our legal system works on a system of reasonable doubt, not absolutes and 100%. There are convicted murderers and rapists sitting in jail cells right now who didn't do the crime, it's just a fact of life that we all have to deal with. If we had a legal system that only imposed punishment on those that we were "100%" about, then nobody would ever get punished for anything.

I also note that the OP doesn't at any point deny the offence.....do the crime, do the time.

i challenged the police on a hand held lidar and won...
he wen't from my face to my number plate and recorded a speed 52 kph faster than i was actually travelling..

henry 351 · 01-09-2011, 02:47 PM

Alleged speeds of 19kmh & 25kmh over the limit...I'd probably be getting my speedo calibration checked rather than fighting it in front of a Magistrate.

Dave3911 · 01-09-2011, 03:05 PM

Quote:

Originally Posted by burnz

i challenged the police on a hand held lidar and won...
he wen't from my face to my number plate and recorded a speed 52 kph faster than i was actually travelling..

Which isn't anything to do with anything I've said at all. Police make mistakes. As do the devices they use. I don't have any problem with that & I accept that as fact. I haven't said hand held lidar(or any other speed detection device) is faultless.... so I don't see what your getting at?

My point is that it doesn't have to be faultless and we can't expect it to be and that fact in itself doesn't negate it's use. With our legal system, ANY crime we seek to punish by law has a chance of getting it wrong, and it does, often. It's just a fact of life we all have to live with, unless your happy to live in a lawless society where people run around stealing, raping and pilaging as they please.

That's what courts are for, you have a right to defend yourself if you feel that a mistake has been made. If the OP feels that he has been wrongly accused of something he hasnt' done, I would urge him to go to court.... infact I would implore him to do so. But it looks to me that he is just trying to get out of punishment for something that he is aware he did and he was aware was against the law.....

davenl5l · 01-09-2011, 03:30 PM

so i guess that means that you think that 24kph over the speed limit is acceptable in this day and age ?

GT-E · 01-09-2011, 04:06 PM

I did not know that Bike cops in VIC use handheld Radar units, in NSW they are all LIDAR units in handheld mode, especially Bikes.
You can go to court and plead leniency, admit to the offences and try to keep your license. That is about it, unless you want to pay for experts and try to challenge the evidence, which rarely works.

EDManual · 01-09-2011, 04:43 PM

Also it didnt happen to be raining when the Radar (not laser) was used? Because!! That CANNOT be done. You get off in that case. Just have to prove it was raining at the time!

Laser can be used in the rain.

Its all in the users guides.

Dave3911 · 01-09-2011, 06:01 PM

Quote:

Originally Posted by GT-E

I did not know that Bike cops in VIC use handheld Radar units, in NSW they are all LIDAR units in handheld mode, especially Bikes.
You can go to court and plead leniency, admit to the offences and try to keep your license. That is about it, unless you want to pay for experts and try to challenge the evidence, which rarely works.

Bike cops in Vic use a vehicle mounted moving mode radar. See link below it's mounted above the blue flashing light on the right hand side of the bike.

http://www.flickr.com/photos/humbers...cs/6005340610/

drew`SEVNT5 · 02-09-2011, 12:27 AM

Sucks to be you.