How often do police speedometers need to be calibrated ?
Discussion
“A road policing vehicle should be fitted with a certified calibrated speedometer regularly tested in accordance with force instructions. The use of non-calibrated speedometers is not encouraged but readings from them may still be admissible in court if the margin by which the limit is exceeded is large and the non-calibrated speedometer would not be reasonably considered to be so inaccurate that the reading could not be relied upon.”
- ACPO / NPCC guideline
“In Nicholas v Penny [1950] 2 All E.R. 89 it was held that a person could be convicted on the evidence of one police officer supported by evidence by him of the reading of a speedometer or other mechanical means, even though there was no evidence that the speedometer had been tested. In that case the defendant was said to be going 10mph in excess of the limit and the court commented on the amount of the excess; had the speed been only, say, 2mph in excess of the limit, they might have called for evidence of the accuracy of the speedometer. In any case, it is in the discretion of the magistrates to accept or reject evidence tendered in speeding as in all other cases. “
- Wilkinson’s 29th edition.
- ACPO / NPCC guideline
“In Nicholas v Penny [1950] 2 All E.R. 89 it was held that a person could be convicted on the evidence of one police officer supported by evidence by him of the reading of a speedometer or other mechanical means, even though there was no evidence that the speedometer had been tested. In that case the defendant was said to be going 10mph in excess of the limit and the court commented on the amount of the excess; had the speed been only, say, 2mph in excess of the limit, they might have called for evidence of the accuracy of the speedometer. In any case, it is in the discretion of the magistrates to accept or reject evidence tendered in speeding as in all other cases. “
- Wilkinson’s 29th edition.
Edited by agtlaw on Thursday 28th May 08:02
'Calibrated', once, when manufactured.
But, from the ACPO guidlines;
Checked for accuracy, 'The patrol vehicle speedometer should be checked for accuracy at the end of a tour of duty after detection of an offending vehicle.'
If using build in speed detection equipment, it'll be at least weekly, but ususally, during the tour of duty after detection of an offending vehicle.
But, from the ACPO guidlines;
Checked for accuracy, 'The patrol vehicle speedometer should be checked for accuracy at the end of a tour of duty after detection of an offending vehicle.'
If using build in speed detection equipment, it'll be at least weekly, but ususally, during the tour of duty after detection of an offending vehicle.
Fatball said:
Boyd Rees said:
Long story cut short.
Pending court appearance for speeding with only evidence being from a patrol cars calibrated speedometer which hasn’t been calibrated for more than 12 months.
Is that within their guidelines?
You don’t drive an rs6 do you?Pending court appearance for speeding with only evidence being from a patrol cars calibrated speedometer which hasn’t been calibrated for more than 12 months.
Is that within their guidelines?
There used to be an agreed policy on calibration which went via ACPO. They were guidelines and guidelines have no moral pressure.
In short, it's up to the court to decide if the speedometer can be accepted as evidence.
What was done in my force was to have regular checks on traffic cars/bikes as these were the ones which were used to indulge in speed checks. For a patrol or GP car, they were checked post report. Most, if not all PCs, would not bother to report and instead use the speeding to inconvenience and check for other offences. The old saying of 'break one law, breaking more' which I was told when being taught, is so very true. However, as pointed out earlier, sometimes the speed is so excessive that there's really no need to check.
Many years ago I chased after a golf GTI in a standard patrol car. The patrol car maxed out about 105 give or take going by the speedo. The golf continued to pull away, but roadworks up ahead enabled me to catch up.
Long story cut short, I charged the driver with a sect 2 RTA.
The next day I had traffic officers assist to record the accuracy of the patrol cars speedo.
After seeking advice and arranging his own expert witnesses the driver pled guilty on the day of his trial.
Long story cut short, I charged the driver with a sect 2 RTA.
The next day I had traffic officers assist to record the accuracy of the patrol cars speedo.
After seeking advice and arranging his own expert witnesses the driver pled guilty on the day of his trial.
Terzo123 said:
Many years ago I chased after a golf GTI in a standard patrol car. The patrol car maxed out about 105 give or take going by the speedo. The golf continued to pull away, but roadworks up ahead enabled me to catch up.
Long story cut short, I charged the driver with a sect 2 RTA.
The next day I had traffic officers assist to record the accuracy of the patrol cars speedo.
After seeking advice and arranging his own expert witnesses the driver pled guilty on the day of his trial.
I was listening to the MPD main channel one evening. A panda unit came up with a call. 'Any unit stop a green Porsce 911, northbound Edgeware road last seen at . . . ' Long story cut short, I charged the driver with a sect 2 RTA.
The next day I had traffic officers assist to record the accuracy of the patrol cars speedo.
After seeking advice and arranging his own expert witnesses the driver pled guilty on the day of his trial.
MP came back with 'Panda unit, what's he done?'
'Bloody left me for dead, that's what the b
d's done.' There were cheers.Megaflow said:
Working on the basis It is going to court, that would suggest greater than 30mph over the limit, in which case, given what the second post suggest, the lack of calibration is not going to help in the slightest.
Quite! I was just curious what margin of error the OP was expecting to try and claim against.We used to check ours every Sunday morning either on a rolling road if we could get to a traffic base or with a calibrated stopwatch against one of a number of measured miles around the county. Then check again after each speeder was processed. I only ever did following checks over 3/10 of a mile and rarely if ever processed drivers at less than 10mph above the limit. With that margin the accuracy of the speedo was rarely questioned.
Any measuring device will have limits on accuracy.
A vehicle speedometer must not read low.
They can read high but by a small margin only, hence the discretionary leeway built in to cameras, whether an officer with handheld will stop you within these reasonable limits. Derek Smith points out the teaching of use speed to stop and do other checks when the speed itself may not be the absolute problem.
A bking or words of advice re speed is very often the result, unless the driver takes fails an attitude test! It is their own fault if other issues then come to light for a ticket/prosecution etc.
If you want a speedometer to be very accurate then it will be costly to engineer and manufacture to the required very tight tolerances.
Is gps more accurate? Is signal reliabilty an issue?
On my car with Garmin satnav at 70mph speedometer indication my satnav shows 68mph.
The accuracy of speedometers is one reason why we have the various options for triggering no action, speed awareness course, fine and points, prosecution and ban.
Maybe those who drive on the limit of the 10%+2 as a guide are really on the edge of the cliff. So easy to drift over the edge then whinge when caught. I used to do this a heck of a lot more but not any more. Yes, in everyday driving I stray over the limit but not up to the cliff edge. Not worth the hassle. There are rare occasions when I do put my foot down but the fun these days is smoother driving, maintaining progress by reading the road, using the torque to exit bends, roundabouts etc.
A vehicle speedometer must not read low.
They can read high but by a small margin only, hence the discretionary leeway built in to cameras, whether an officer with handheld will stop you within these reasonable limits. Derek Smith points out the teaching of use speed to stop and do other checks when the speed itself may not be the absolute problem.
A b
king or words of advice re speed is very often the result, unless the driver takes fails an attitude test! It is their own fault if other issues then come to light for a ticket/prosecution etc.If you want a speedometer to be very accurate then it will be costly to engineer and manufacture to the required very tight tolerances.
Is gps more accurate? Is signal reliabilty an issue?
On my car with Garmin satnav at 70mph speedometer indication my satnav shows 68mph.
The accuracy of speedometers is one reason why we have the various options for triggering no action, speed awareness course, fine and points, prosecution and ban.
Maybe those who drive on the limit of the 10%+2 as a guide are really on the edge of the cliff. So easy to drift over the edge then whinge when caught. I used to do this a heck of a lot more but not any more. Yes, in everyday driving I stray over the limit but not up to the cliff edge. Not worth the hassle. There are rare occasions when I do put my foot down but the fun these days is smoother driving, maintaining progress by reading the road, using the torque to exit bends, roundabouts etc.
It sounds like OP is hoping for a very "digital" - speedo hasn't been calibrated in last 12 months, means the evidence is completely thrown out.
As opposed to the far more likely "It will just be accepted" or "Even if it hasn't been calibrated, is it likely to be over-reading by 30mph".
As opposed to the far more likely "It will just be accepted" or "Even if it hasn't been calibrated, is it likely to be over-reading by 30mph".
sospan said:
Any measuring device will have limits on accuracy.
A vehicle speedometer must not read low.
They can read high but by a small margin only, hence the discretionary leeway built in to cameras, whether an officer with handheld will stop you within these reasonable limits. Derek Smith points out the teaching of use speed to stop and do other checks when the speed itself may not be the absolute problem.
A bking or words of advice re speed is very often the result, unless the driver takes fails an attitude test! It is their own fault if other issues then come to light for a ticket/prosecution etc.
If you want a speedometer to be very accurate then it will be costly to engineer and manufacture to the required very tight tolerances.
Is gps more accurate? Is signal reliabilty an issue?
On my car with Garmin satnav at 70mph speedometer indication my satnav shows 68mph.
The accuracy of speedometers is one reason why we have the various options for triggering no action, speed awareness course, fine and points, prosecution and ban.
Maybe those who drive on the limit of the 10%+2 as a guide are really on the edge of the cliff. So easy to drift over the edge then whinge when caught. I used to do this a heck of a lot more but not any more. Yes, in everyday driving I stray over the limit but not up to the cliff edge. Not worth the hassle. There are rare occasions when I do put my foot down but the fun these days is smoother driving, maintaining progress by reading the road, using the torque to exit bends, roundabouts etc.
A vehicle speedometer must not read low.
They can read high but by a small margin only, hence the discretionary leeway built in to cameras, whether an officer with handheld will stop you within these reasonable limits. Derek Smith points out the teaching of use speed to stop and do other checks when the speed itself may not be the absolute problem.
A b
king or words of advice re speed is very often the result, unless the driver takes fails an attitude test! It is their own fault if other issues then come to light for a ticket/prosecution etc.If you want a speedometer to be very accurate then it will be costly to engineer and manufacture to the required very tight tolerances.
Is gps more accurate? Is signal reliabilty an issue?
On my car with Garmin satnav at 70mph speedometer indication my satnav shows 68mph.
The accuracy of speedometers is one reason why we have the various options for triggering no action, speed awareness course, fine and points, prosecution and ban.
Maybe those who drive on the limit of the 10%+2 as a guide are really on the edge of the cliff. So easy to drift over the edge then whinge when caught. I used to do this a heck of a lot more but not any more. Yes, in everyday driving I stray over the limit but not up to the cliff edge. Not worth the hassle. There are rare occasions when I do put my foot down but the fun these days is smoother driving, maintaining progress by reading the road, using the torque to exit bends, roundabouts etc.
Bigends said:
We used to check ours every Sunday morning either on a rolling road if we could get to a traffic base or with a calibrated stopwatch against one of a number of measured miles around the county. Then check again after each speeder was processed. I only ever did following checks over 3/10 of a mile and rarely if ever processed drivers at less than 10mph above the limit. With that margin the accuracy of the speedo was rarely questioned.
Similar here. Although min for us was 2/10 of a mile. I'd either get someone to laser the car or go though the measured distances with a stop watch.
Never had a problem with them at court.
This was in a car without a calibrated speedo.
Only if it was a lot over the speed limit as well. Normally court speeds.
BertieWooster said:
Just out of interest - is a calibrated speedometer the only way traffic BiB can measure speed while on the move?
We predominantly use radar over here, but also have calibrated speedometers (I think I have only written one ticket using the latter).
My post above explains how I do it without it being calibrated. We predominantly use radar over here, but also have calibrated speedometers (I think I have only written one ticket using the latter).
Don't have to be traffic either.
BertieWooster said:
Just out of interest - is a calibrated speedometer the only way traffic BiB can measure speed while on the move?
We predominantly use radar over here, but also have calibrated speedometers (I think I have only written one ticket using the latter).
They still use VASCAR over here. We predominantly use radar over here, but also have calibrated speedometers (I think I have only written one ticket using the latter).
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