VASCAR…..how accurate is it?
Discussion
The best answer is that it's as accurate as it's last calibration and it's operator.
As a device on it's own, it's 100% accurate, as it's only a very simple combination of odometer, stopwatch and calculator. In effect, it's a modern version of the oldest speed measuring method, which was a bobby hiding in a bush with a stopwatch and a chart showing different speeds for different times over a set distance.
Operators are taught to recalibrate the device regularly to take account of tyre wear, etc, and this is done over a measured mile / half mile.
The operation of the device is simple enough - two switches, time on/off and distance on/off. Switch the time on as the target vehicle passes a fixed point, and the distance on as the Police vehicle passes the same fixed point. The time is switched off at a further fixed point and so is the distance. The machine makes a simple time/distance calculation and gives an average speed for the target vehicle.
The average speed is more accurately calculated over a longer distance, and it's best practice for the target vehicle to remain in view of the operator at all time - although this isn't absolutely necessary.
It can be used in a static vehicle using pre-set distances as well.
But like I said - the simple answer is that it's as accurate as it's last calibration and it's operator.
As a device on it's own, it's 100% accurate, as it's only a very simple combination of odometer, stopwatch and calculator. In effect, it's a modern version of the oldest speed measuring method, which was a bobby hiding in a bush with a stopwatch and a chart showing different speeds for different times over a set distance.
Operators are taught to recalibrate the device regularly to take account of tyre wear, etc, and this is done over a measured mile / half mile.
The operation of the device is simple enough - two switches, time on/off and distance on/off. Switch the time on as the target vehicle passes a fixed point, and the distance on as the Police vehicle passes the same fixed point. The time is switched off at a further fixed point and so is the distance. The machine makes a simple time/distance calculation and gives an average speed for the target vehicle.
The average speed is more accurately calculated over a longer distance, and it's best practice for the target vehicle to remain in view of the operator at all time - although this isn't absolutely necessary.
It can be used in a static vehicle using pre-set distances as well.
But like I said - the simple answer is that it's as accurate as it's last calibration and it's operator.
It is only as accurate as the operator!
Imagine a set of scales where dependant on where you were standing the needle in the scale read at a slightly different place. In addition to that the scales could be easily 'lent on' to make the weight seem heavier if needed without showing any evidence that this happened.
It is technically possible for scales or VASCAR to be exactly right. How accurate both are comes down to how good the user is, how diligent they are and how diligent they *want to be*!
Imagine a set of scales where dependant on where you were standing the needle in the scale read at a slightly different place. In addition to that the scales could be easily 'lent on' to make the weight seem heavier if needed without showing any evidence that this happened.
It is technically possible for scales or VASCAR to be exactly right. How accurate both are comes down to how good the user is, how diligent they are and how diligent they *want to be*!
Fot Fast said:
Ok….I was thinking more in terms of the distance from the “chase” vehicle to the “target” vehicle as opposed to the distance actually covered. Surely when you start to get too far away the depth perception plays a greater part in any inaccuracies??
The timings should be made from a fixed point, which is preferably on the road surface - the white squares you see painted on roads are VASCAR markings. Another good way to do it is from "bridge flashes" - when a vehicle passes under a bridge, the shadow makes it look darker for a fraction of a second. That's why VASCAR is ideally suited for enforcement on motorways and dual carriageways.
justinp1 said:
It is only as accurate as the operator!
Imagine a set of scales where dependant on where you were standing the needle in the scale read at a slightly different place. In addition to that the scales could be easily 'lent on' to make the weight seem heavier if needed without showing any evidence that this happened.
It is technically possible for scales or VASCAR to be exactly right. How accurate both are comes down to how good the user is, how diligent they are and how diligent they *want to be*!
Measurement changes the system (basic quantum mechanics) - Streaky Imagine a set of scales where dependant on where you were standing the needle in the scale read at a slightly different place. In addition to that the scales could be easily 'lent on' to make the weight seem heavier if needed without showing any evidence that this happened.
It is technically possible for scales or VASCAR to be exactly right. How accurate both are comes down to how good the user is, how diligent they are and how diligent they *want to be*!
R_U_LOCAL said:
As a device on it's own, it's 100% accurate, .
This is simply incorrect. There is absolutely no such thing as an instrument that is 100% accurate. All measurement instruments have errors which mean that to the reading must be applied a band of error. In the case of the Meggitt Controls vascar the makers data sheet states +/- 2% which means at a reading of 100 mile/h the actual speed may be 98..102 mile/h. Furthermore most vascars read to a precision of 3 places of decimals, eg 100.003 which is regularly trotted out in court as though that that somehow implies that the device must be accurate to +/- 0.001 mile/h. It is not.
The errors estimated by the makers include changes in rolling radius of tyres of the vehicle due to spoeed, tyre pressure, tyre tolerance, temperature, the accuracy of the on board time cock ( athough that will be extremely accurate) and random error introduced by the operators reaction time when throwing the switches.
I successfully fought a case on this and avoided a ban in Extere some years ago. The reporting officer was rather angry claiming too that "....it's 100% accurate !"
Advice to those who chose to fight this in marginal cases is to find out the model number and maker and obtain and read the data sheet ...the accuracy figure will be there and the court cannot infer that the device is more accurate than the makers claim.
R_U_LOCAL said:
I'll see you in court. 
I don't have time right now, but I'll post on this tomorrow.
And I would welcome the opportunity of "seeing you in court" any time you wanted RU, if only to highlight the gross inadequacy of the system and to put you in your place along with all the other BiB who try it on with VASCAR on a regular basis.
jith said:
R_U_LOCAL said:
I'll see you in court.
I don't have time right now, but I'll post on this tomorrow.
And I would welcome the opportunity of "seeing you in court" any time you wanted RU, if only to highlight the gross inadequacy of the system and to put you in your place along with all the other BiB who try it on with VASCAR on a regular basis.
I'm quaking in my boots.
He wouldn't have walked away with no points if he admitted driving at 85MPH in court. If you're going to admit breaking the speed limit, then there's no point in pleading not guilty. Irrespective of what your argument was over your actual speed, the offence is driving above the speed limit - the actual speed is only taken into consideration at the point where you're sentenced. And 6 points, rather than a ban would back this up.
lambocop said:
I take it by everyone refering to Vascar they mean Pilot ?? If so I will be standing next to R_U_LOCAL when you try to knock this VASCAR and then we play the video evidence from Pilot !!
People you are knocking something you know nothing about, have heard stories about are not trained on and have not seen first hand. Other than Traffic Bib on here and Hughesie2 I don't think any of you are trained to comment.....
People you are knocking something you know nothing about, have heard stories about are not trained on and have not seen first hand. Other than Traffic Bib on here and Hughesie2 I don't think any of you are trained to comment.....
not knocking it..... just pointing out hard fact. If the training one receives tells one that you and the instrument will be 100% accurate then the training is seriously flawed.
I don't think many on PH want to accept something that can measure a cars speed and be accurate .... unfortunately for drivers though it is not difficult to use !
Officers spend a week on a course in order to repeat over and over and over checks to ensure they are capable of doing it properly. It is so simple to use but the course requires incredible accuracy or you fail ..... thus the practice.
It is all recorded on video now as opposed to a few years ago so if in doubt the court can decide how 'accurate' it is.
Officers spend a week on a course in order to repeat over and over and over checks to ensure they are capable of doing it properly. It is so simple to use but the course requires incredible accuracy or you fail ..... thus the practice.
It is all recorded on video now as opposed to a few years ago so if in doubt the court can decide how 'accurate' it is.
R_U_LOCAL said:
jith said:
R_U_LOCAL said:
I'll see you in court.
I don't have time right now, but I'll post on this tomorrow.
And I would welcome the opportunity of "seeing you in court" any time you wanted RU, if only to highlight the gross inadequacy of the system and to put you in your place along with all the other BiB who try it on with VASCAR on a regular basis.
I'm quaking in my boots.
Dear, dear me! Primary school memories no doubt.
lambo cop said:
People you are knocking something you know nothing about, have heard stories about are not trained on and have not seen first hand. Other than Traffic Bib on here and Hughesie2 I don't think any of you are trained to comment.....
Oh believe me, I know absolutely everything about it.
More later.
lambo cop said:
As for this......
You had a crap lawer or tried to represent yourself on stories you had heard. If this speed was so wrong with the calibration book as evidence and the video being played, as the officer was giving his evidence, the record of repairs on the vehicle etc etc, if your speed was so wrong and it was down to the operator or the equipment you would have walked with no points. With all the above evidence if the device / operator was wrong it would have showed up for all the court to see.
blueyes said:
Judging by my experience...
... about 16.3mph out.
My speed = 85
Vascar says = 101.3
Court said = 6 points
To the plods who tucked me up... I hope you get a lump in your sack.
... about 16.3mph out.
My speed = 85
Vascar says = 101.3
Court said = 6 points
To the plods who tucked me up... I hope you get a lump in your sack.
You had a crap lawer or tried to represent yourself on stories you had heard. If this speed was so wrong with the calibration book as evidence and the video being played, as the officer was giving his evidence, the record of repairs on the vehicle etc etc, if your speed was so wrong and it was down to the operator or the equipment you would have walked with no points. With all the above evidence if the device / operator was wrong it would have showed up for all the court to see.
It was VASCAR so there was no video. Two plod in a fully marked up traffic car on the hard shoulder of the M5. I was doing 85mph, came around the corner, saw them and just eased off the gas. There was no way I was doing well over the ton (which it would have had to been to "average" the 101.3 they said I was doing) as (from track experience) the roof on the TVR whistled like a train over the ton. They pulled me over, I got in the car, they showed me the readout and I admitted to 85 and asked for a FPN stating there was no way I was doing over the ton. They refused saying even if they included a possible 10% operator error it was still over 90pmh so it had to go to court. At that point I knew I was stuffed: two plods word against mine. No court would ever believe me, even with the best solicitor in the world! I wrote a nice letter and got 6 points for the trouble. Oh yes, and I didn't get into their car with the wrong attitude and start shouting the odds. I was fully prepared for a telling off or at worst an FPN.
Not to worry though, due to this bad experience I've spent the last 6 years finding loopholes and advising people so that, to date, I have robbed them of 28 points and at least £400 of fines.
And my wish, about a lump in their sacks, still stands.
VASCAR is as accurate as the operator decides it is at the time of the specific check being recorded.
The training endorses the policy that if the operator is unsure of the accuracy of the check, then they should bin it! There will be another one along in a few seconds.
Why prosecute something that you are not sure about when a better one will appear in a minute?
VASCAR relies on integrity of the operator.
Training requires a series of checks in all speed and operator method situations. These are recorded and an overall error of less than 1 mph in any check and overall on the series of checks of less than .5 mph otherwise the operator is not authorised to operate the device.
That was the state when I did my training on VASCAR.
My average error during the training test was .24 mph overall ranging over a series of checks including prefed checks at between 30 mph and 120mph and following checks over the same speed ranges and varying distances. Reverse checks were also tested when the vehicle targetted was travelling the opposite way from the moving police vehicle.
The longer the check over distance, the more accurate the result!!!
I do not believe that an operator would be 16mph out on a single check. At 85 mph, the operator would have had to be many seconds late entering the check start point time or early in entering the end of check time into the device, even over 2/10th of a mile distance which was in those days, the minimum distance allowed.
Errors of more than 5 mph would be rare indeed as the operator would be very late in ending the check or the vehicle travelling very fast over a very short distance.
I have to say though that I was not there when a 16mph error was recorded!
Magistrates are taken out on demonstration sessions by police officers to be shown how the device works and how the operators use it. Most magistrates will be aware of the methods and standing operating procedures regarding these types of devices and will have witnessed practical operating procedures.
Most VASCAR checks are favoured towards the subject put into the check because the recorded speed is an average and does not require a top speed to be registered in the report sent to the magistrates!
The training endorses the policy that if the operator is unsure of the accuracy of the check, then they should bin it! There will be another one along in a few seconds.
Why prosecute something that you are not sure about when a better one will appear in a minute?
VASCAR relies on integrity of the operator.
Training requires a series of checks in all speed and operator method situations. These are recorded and an overall error of less than 1 mph in any check and overall on the series of checks of less than .5 mph otherwise the operator is not authorised to operate the device.
That was the state when I did my training on VASCAR.
My average error during the training test was .24 mph overall ranging over a series of checks including prefed checks at between 30 mph and 120mph and following checks over the same speed ranges and varying distances. Reverse checks were also tested when the vehicle targetted was travelling the opposite way from the moving police vehicle.
The longer the check over distance, the more accurate the result!!!
I do not believe that an operator would be 16mph out on a single check. At 85 mph, the operator would have had to be many seconds late entering the check start point time or early in entering the end of check time into the device, even over 2/10th of a mile distance which was in those days, the minimum distance allowed.
Errors of more than 5 mph would be rare indeed as the operator would be very late in ending the check or the vehicle travelling very fast over a very short distance.
I have to say though that I was not there when a 16mph error was recorded!
Magistrates are taken out on demonstration sessions by police officers to be shown how the device works and how the operators use it. Most magistrates will be aware of the methods and standing operating procedures regarding these types of devices and will have witnessed practical operating procedures.
Most VASCAR checks are favoured towards the subject put into the check because the recorded speed is an average and does not require a top speed to be registered in the report sent to the magistrates!
Edited by mg6b on Friday 6th April 10:59
Edited by mg6b on Friday 6th April 11:01
mg6b said:
Why prosecute something that you are not sure about when a better one will appear in a minute?
Why?
Because they CAN!
Sunny summer evening on a deserted M5. Young man alone in a sports car. Two trafpol with nothing better to do than ruin someones evening.
I'm not tarring all plod with the same brush as, apart from this occasion, I've always been treated fairly, just had to post to point out that VASCAR can and has been used to convict an innocent person.
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