Possible Speeding Ticket

[durhamplumber]

Not if it was a 20 mph limit..

London now is full of 20 mph limits...its a bloody pain

20 in a 20limit...30 in a 30.simples

 

[durhamplumber]

Thats certainly true, 35 on a car speedometer is prob 32 -so within the allowance.

Thankfully they are doing away with all that nonsense excuse

 

[durhamplumber]

Go for a spin with the sat nav speedo on - see what your actual speed was when doing 35 on the car speedo? Normally much lower...

How do you know which is accurate?

 

[rsgaz]

Thankfully they are doing away with all that nonsense excuse

No they are not. Manufacturers only have to comply with "Document 42010X0513(03)" under European Union Law, which states...

0 ≤ (V1 – V2) ≤ 0,1xV2 + 4 km/h

...which means, a vehicle's speedometer must never under-read, but may over-read by 10% plus 4kmh of the actual speed. That's not changing any time soon. So you are always going slightly slower than the shown speed.

 

[IWalkLikeHimaMartian]

Thats certainly true, 35 on a car speedometer is prob 32 -so within the allowance.

That would have been a fair comment about 25 years or so ago. My 28 year old, nearly classic car has more than a 10% error, always below the real speed.

Thankfully they are doing away with all that nonsense excuse

In my experience modern speedos are much more accurate, when compared to the speed readouts on roadside advisory signs.

 

[EddieM]

can also be affected by changing the as built spec wheels and tyres as the Speedo would need recalibrating.

 

[rsgaz]

How do you know which is accurate?

Both are, to a degree.

If you google GPS inaccuracy, you find all sorts of figures, roughly 5 metres, but this is a 'skew error' because of current atmospheric conditions where you are at the time. But this skew is consistent as long as you're not in a thunderstorm, so the speed calculation is very accurate, even if the device only bothers to calculate your speed in a 2D vector, ignoring your changes in altitude.

As for vehicle speedometers, it's not the 80's any more, they don't use a bowden cable, the speed is calculated from the vehicle's VSS, electronically. So, unless you have changed your wheels or your tyre pressures are way off, then, again, very accurate. Any skew error seen in this system, as in "my car's speedo is always 2mph above my GPS", is designed into the system on purpose by the manufacturers, to comply with the rules. The only 'percentage error' possible is due to tyre tread wear, which would account for less than 1% inaccuracy, going from a new tyre, to a completely worn one.

 

[durhamplumber]

≤ (V1 – V2) ≤ 0,1xV2 + 4 km/h

...which means, a vehicle's speedometer must never under-read, but may over-read by 10% plus 4kmh of the actual speed. That's not changing any time soon. So you are always going slightly slower than the shown speed.

The above equation looks v dubious . Especially with no explanation of what V2 and V2 are...or any other parameters

 

[durhamplumber]

So...40mph limit...motorist thinks oh ...I'm allowed to do 44 on Speedo..so does 44mph....how about.....god forbid ..you do 36 according to Speedo...to allow for errors!!!...should be zero tolerance for fekwit speeding motorists and litter louts...and especially the dog shy..te flingers.

 

[rsgaz]

no explanation of what V2[sic] and V2 are

I gave you the name of the document, google it.

or any other parameters

There aren't any other parameters.

 

[SirGalahad]

I suspect most people would prefer more police officers in cars patrolling than using speed cameras.

 

[motorbiking]

10%+2MPH is the prosecution threshold.
10%+9MPH is the summons/fixed penalty threshold.

So a reading of 35mph will probably result in nothing happening to speed awareness at worse.

Very few cameras have film in - but the more modern ones have data cards in them, so sync automatically.

 

[durhamplumber]

10%+2MPH is the prosecution threshold.
10%+9MPH is the summons/fixed penalty threshold.

So a reading of 35mph will probably result in nothing happening to speed awareness at worse.

Very few cameras have film in - but the more modern ones have data cards in them, so sync automatically.

Film!!!..Really.I seriously doubt any film speed cameras are in operation.

 

[JohnD]

no explanation of what V2 and V2 are

if he'd wanted you to know what he meant, or if he was used to writing or quoting technical documents, he would have said "the speed displayed (V1) and the true speed (V2)."

There are some simple conventions about the use of abbs, TLAs etc. You explain them at first use.

 

[motorbiking]

Film!!!..Really.I seriously doubt any film speed cameras are in operation.

You'd be surprised.. I spent almost 10 years training fat donut eaters who couldn't ride for.. well donuts. They confessed most of their secrets. Most of the cameras were installed in the pyramid funding years (2000-2007) and haven't been upgraded. Plenty of wet cameras around along with old digital cameras which need a physical download. Hence the scamerati don't bother collecting the pictures as it costs money to send an operator out.

Police are incentivised to offer speed awareness courses as they can p̶r̶o̶f̶i̶t̶ recover costs, where as a fine or fixed penalty goes direct to the government.