Which speed would I be done for?
Discussion
Say I'm driving down the motorway, my speedo says I'm doing 94Mph, my Road Angel says I'm doing 89Mph. Un-known to me I'm being followed by the Police who pull me over. Do they measure my speed using their Speedo?
Thus, if their speedo is reading 95Mph when my speedo says I'm doing 94Mph and when my RA says I'm only doing 89Mph. What happens? They ask my speed, I say 89Mph because RA speed is more accurate. They dont believe me, where do I stand?
On the same note. If I get flashed by a Gatso would it be more likely to register me as going the speed my speedo says I'm going or at the speed my RA says I'm going?!?
Thus, if their speedo is reading 95Mph when my speedo says I'm doing 94Mph and when my RA says I'm only doing 89Mph. What happens? They ask my speed, I say 89Mph because RA speed is more accurate. They dont believe me, where do I stand?
On the same note. If I get flashed by a Gatso would it be more likely to register me as going the speed my speedo says I'm going or at the speed my RA says I'm going?!?
Say I'm driving down the motorway, my speedo says I'm doing 94Mph, my Road Angel says I'm doing 89Mph. Un-known to me I'm being followed by the Police who pull me over. Do they measure my speed using their Speedo?
Thus, if their speedo is reading 95Mph when my speedo says I'm doing 94Mph and when my RA says I'm only doing 89Mph. What happens? They ask my speed, I say 89Mph because RA speed is more accurate. They dont believe me, where do I stand?
On the same note. If I get flashed by a Gatso would it be more likely to register me as going the speed my speedo says I'm going or at the speed my RA says I'm going?!?
Is this post for real ?
Whatever device you have in your car makes not a jot. The Police will be using a calibrated device and they will use that to judge your speed. As for the second question I would guess that your Road Angel would give you a more accurate representation of your speed.
RA speed is calculated as the average of speeds measured between a series of points measured by satellite fix. So if you are travelling dead straight at a constant speed it will be reasonably accurate. If you travel around a bend your instantaneous speed ( as speedo) will be higher than the RA reading. Also if you accelerate, the RA speed will lag the speedo speed.
RA's are very very accurate if you are in a straight line between the two sample points (which depending on the chipset are either 1 second or 2 seconds apart).
The RA was exactly correct with the speed trap at Bruntingthorpe - and unless you are doing significant acceleration or bends will be the most accurate of it and the speedo.
As for police cars, they will usually use VASCAR to measure your speed behind you - and that is to within 1-2% (the operator test for the license to operate it actually ensures that they have to be within 0.05% from memory). As it uses a calibrated sensor on the drive shaft to measure the distance, it doesn't suffer from non-linear spring rates which a normal analogue speedo suffers from.
To be legal your speedo must always be either dead accurate or over estimate the speed - most over estimate by around 10% unless it's a digital speedo (ala TVR Tamora etc.) when as it effectivly uses the same system as the VASCAR unit then it too should be very accurate (and indeed the tamora at Bruntingthorpe was absolutly spot on even around 160mph).
You can argue that your speedo was inaccurate, but it won't get you far unless you could prove the car failed its type approval, and then IMHO it would be down to the judge to take the mitigating circumstances into account, but he/she would be under no obligation to do so as speeding per-say is an "absolute" offence.
For more details you can read www.speed-trap.co.uk/Accused_Home/Gadgets/Gadgets_Home.htm
J
The RA was exactly correct with the speed trap at Bruntingthorpe - and unless you are doing significant acceleration or bends will be the most accurate of it and the speedo.
As for police cars, they will usually use VASCAR to measure your speed behind you - and that is to within 1-2% (the operator test for the license to operate it actually ensures that they have to be within 0.05% from memory). As it uses a calibrated sensor on the drive shaft to measure the distance, it doesn't suffer from non-linear spring rates which a normal analogue speedo suffers from.
To be legal your speedo must always be either dead accurate or over estimate the speed - most over estimate by around 10% unless it's a digital speedo (ala TVR Tamora etc.) when as it effectivly uses the same system as the VASCAR unit then it too should be very accurate (and indeed the tamora at Bruntingthorpe was absolutly spot on even around 160mph).
You can argue that your speedo was inaccurate, but it won't get you far unless you could prove the car failed its type approval, and then IMHO it would be down to the judge to take the mitigating circumstances into account, but he/she would be under no obligation to do so as speeding per-say is an "absolute" offence.
For more details you can read www.speed-trap.co.uk/Accused_Home/Gadgets/Gadgets_Home.htm
J
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