How does "Vascar" work?
02 March 2004, 11:21 PM
#1
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How does "Vascar" work?
Can anyone explain how this works?
I was stopped by the police the other day after they had "clocked" me while sitting on an overhead bridge. The were stationary and I passed under them on m-way.
They stopped me and told me the vascar had recorded my speed etc etc.
I just wondered how this technology actually captures your speed.
I appreciate that speed = distance / time, but how does it calculate these variables?
A gatso obviously provides evidence that your car travelled "x" distance in "y" time (via photographs) and can thus tell your speed between 2 points, but as far as I know, the Vascar doesn't have photographic proof that you covered a certain amount of ground in a specified time in order to calculate your speed so how does it work???
Confused!
I was stopped by the police the other day after they had "clocked" me while sitting on an overhead bridge. The were stationary and I passed under them on m-way.
They stopped me and told me the vascar had recorded my speed etc etc.
I just wondered how this technology actually captures your speed.
I appreciate that speed = distance / time, but how does it calculate these variables?
A gatso obviously provides evidence that your car travelled "x" distance in "y" time (via photographs) and can thus tell your speed between 2 points, but as far as I know, the Vascar doesn't have photographic proof that you covered a certain amount of ground in a specified time in order to calculate your speed so how does it work???
Confused!
02 March 2004, 11:24 PM
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Visual Average Speed Computer And Recorder.
This system is a timing computer, it has to be set for the distance first, between a bridge and a marker post for example and then the police officer presses a button at the start of the timed position when the vehicle passes, the bridge. When the vehicle passes the second position, the marker post, he then presses the button again, this will then give an instant average speed between two points.
Common places for the use of VASCAR is on motorways, in which the police car will wait just out of sight on a slip road, and time the vehicle between two points, usually the white painted square or round markings on the road, but any fixed points can be used, that the distance between them is known. They can also use it when they are following you or when you are following them.
The minimum distance the police are allowed to is 0.125 miles - one-eighth of a mile. Under exceptional circumstances, they're allowed to go down to 0.07 miles but only in pre-fed or dial-in distance modes where the start and end points are not shadows. Police helicopters and Motorbikes can take the same measurements
Those white squares and circles that are painted on the road are used for VASCAR systems. They are set distances apart, and quite often are quite visible to the police from a great distance, they could be parked up to half a mile away and still get a speed reading of an offending vehicle. But remember any fixed point can be used, such as a lamppost.
If Vascar is used correctly the margin of error is presumed to be the same at either end of the check.
The Home Office allows a percentage of error for the overall check and this built into the operating procedure.
Each and every police officer undergoes an intensive training course to establish their margin of error. If it falls within the guide lines then it is "acceptable".
The speed you saw will have been your average speed between two fixed points, shadows under bridges, road markings on the surface etc.
Visual Average Speed Computer And Recorder.
This system is a timing computer, it has to be set for the distance first, between a bridge and a marker post for example and then the police officer presses a button at the start of the timed position when the vehicle passes, the bridge. When the vehicle passes the second position, the marker post, he then presses the button again, this will then give an instant average speed between two points.
Common places for the use of VASCAR is on motorways, in which the police car will wait just out of sight on a slip road, and time the vehicle between two points, usually the white painted square or round markings on the road, but any fixed points can be used, that the distance between them is known. They can also use it when they are following you or when you are following them.
The minimum distance the police are allowed to is 0.125 miles - one-eighth of a mile. Under exceptional circumstances, they're allowed to go down to 0.07 miles but only in pre-fed or dial-in distance modes where the start and end points are not shadows. Police helicopters and Motorbikes can take the same measurements
Those white squares and circles that are painted on the road are used for VASCAR systems. They are set distances apart, and quite often are quite visible to the police from a great distance, they could be parked up to half a mile away and still get a speed reading of an offending vehicle. But remember any fixed point can be used, such as a lamppost.
If Vascar is used correctly the margin of error is presumed to be the same at either end of the check.
The Home Office allows a percentage of error for the overall check and this built into the operating procedure.
Each and every police officer undergoes an intensive training course to establish their margin of error. If it falls within the guide lines then it is "acceptable".
The speed you saw will have been your average speed between two fixed points, shadows under bridges, road markings on the surface etc.
02 March 2004, 11:24 PM
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The VASCAR device has been in use for many years in the UK and represents the most lenient form of enforcement to the motorist. It records the average speed of a vehicle and this will display a lower speed than the motorist was actually travelling.
The device measures time over distance and this produces an average speed. The police are trained over a prolonged period in order to determine their margin of error. The margin of error is in fact a variance of anticipation and not an error of reaction. This is often where people assume that an officer can have an area of weakness during its operation. It must be stressed that any error must be on the anticipation of the operator and not on their reaction time.
Try it your self. Set a stopwatch running and see how close to five seconds you can stop the timer running. After a few attempts you will find that you have anticipated the stop point very accurately and this how it works. When a vehicle is observed approaching the start of the check distance the operating officer can see both the start of the check and the target vehicle and can easily anticipate when the vehicle will strike the starting point. The same happens at the end of the check. The margin of error is very very small and often less than .03 mph.
It is the same anticipation as a group of people clapping in time with one another because they can anticipate when the next strike of the hands occurs. It is the same as someone recording the lap time of an athlete crossing the start and finish line: the timer anticipates the moment when the runner passes the start finish point and can record a very accurate time.
The VASCAR is a very accurate means of determining the speed of a vehicle and the motorist will have to prove that the operator did not operate it correctly, a very difficult thing to do. It is very unlikely that you will have a defence if caught with this device because you will have to show that the operator did not act in accordance with the guidelines. Most VASCAR check sites have been approved and are the only static sites used especially on Motorways where strict guidelines as to use are in force.
The following check using VASCAR is even more difficult for the driver seeking to avoid detection. The police drivers know exactly where to sit to be in a driver's blind spot and so often they can be very close to the target vehicle without the driver being aware. This also holds good for the following check using the calibrated speedometer.
VASCAR units in police vehicles have to be calibrated on a regular basis and from my experience they are, in fact most officers check the device at the start and end of each working day and that is well above the recommendations. If a case is contested the prosecution is often dropped if the device has not been calibrated correctly and in fairness officers generally do not use the device if the calibration has not been carried out.
The device measures time over distance and this produces an average speed. The police are trained over a prolonged period in order to determine their margin of error. The margin of error is in fact a variance of anticipation and not an error of reaction. This is often where people assume that an officer can have an area of weakness during its operation. It must be stressed that any error must be on the anticipation of the operator and not on their reaction time.
Try it your self. Set a stopwatch running and see how close to five seconds you can stop the timer running. After a few attempts you will find that you have anticipated the stop point very accurately and this how it works. When a vehicle is observed approaching the start of the check distance the operating officer can see both the start of the check and the target vehicle and can easily anticipate when the vehicle will strike the starting point. The same happens at the end of the check. The margin of error is very very small and often less than .03 mph.
It is the same anticipation as a group of people clapping in time with one another because they can anticipate when the next strike of the hands occurs. It is the same as someone recording the lap time of an athlete crossing the start and finish line: the timer anticipates the moment when the runner passes the start finish point and can record a very accurate time.
The VASCAR is a very accurate means of determining the speed of a vehicle and the motorist will have to prove that the operator did not operate it correctly, a very difficult thing to do. It is very unlikely that you will have a defence if caught with this device because you will have to show that the operator did not act in accordance with the guidelines. Most VASCAR check sites have been approved and are the only static sites used especially on Motorways where strict guidelines as to use are in force.
The following check using VASCAR is even more difficult for the driver seeking to avoid detection. The police drivers know exactly where to sit to be in a driver's blind spot and so often they can be very close to the target vehicle without the driver being aware. This also holds good for the following check using the calibrated speedometer.
VASCAR units in police vehicles have to be calibrated on a regular basis and from my experience they are, in fact most officers check the device at the start and end of each working day and that is well above the recommendations. If a case is contested the prosecution is often dropped if the device has not been calibrated correctly and in fairness officers generally do not use the device if the calibration has not been carried out.
02 March 2004, 11:26 PM
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The above is taken from a post on 5ive-o.com from a traffic officer. It is correct and I hope it answers your question.
Edited to say : the last post by me was!! Ian got in too quickly!!
Edited to say : the last post by me was!! Ian got in too quickly!!
Last edited by Danbo; 02 March 2004 at 11:27 PM.
02 March 2004, 11:29 PM
#5
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http://www.ukspeedtraps.co.uk/speed03.htm
Also details more information, but I will corroborate with Danbo that the information in his post is Correct
Also details more information, but I will corroborate with Danbo that the information in his post is Correct
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