securespark said:
The main reason that no-one gets done for driving between 70-80 mph is that the 10% +2mph rule makes the minimum speed at which you can be prosecuted on a 70mph road is 79mph.
"Rule" is an odd word to use. Let's start with the horse's mouth...
The ACPO said:
The Guidance
ACPO's guidance has been formulated having taken account of the need for proportionality (especially with the introduction of Human Rights legislation) and the need for targeting in order to maximise the potential of scarce police resources and make a substantial contribution to the multi-agency road death and injury reduction effort.
Driving at any speed over the limit is an offence. The differing speed limits are generally related, and proportionate, to the risks to all road users using that road. Where police officers consider that an offence has been committed i.e. that a motorist has driven at any speed over the relevant speed limit, they should consider whether it is appropriate to take enforcement action against the offender.
The Police Service now uses technology that enables it to prove that an offence has been committed as soon as a driver exceeds the relevant speed limit by a very small margin. Motorists will therefore be at risk of prosecution immediately they exceed any legal speed limit.
The guidance to police officers is that it is anticipated that, other than in the most exceptional circumstances, the issue of fixed penalty notices and summonses is likely to be the minimum appropriate enforcement action as soon as the following speeds have been reached:
[code:1]Limit Fixed Penalty Summons
20 mph 25 mph 35 mph
30 mph 35 mph 50 mph
40 mph 46 mph 66 mph
50 mph 57 mph 76 mph
60 mph 68 mph 86 mph
70 mph 79 mph 96 mph[/code:1]
This guidance does not and cannot replace the police officer's discretion and they may decide to issue a summons or a fixed penalty notice in respect of offences committed at speeds lower than those set out in the table. Moreover, in particular circumstances, driving at speeds lower than the legal limit may result in prosecution for other offences, for example dangerous driving or driving without due care and attention when the speed is inappropriate and inherently unsafe.
AFAIK, the reason for the margin is simply one of pragmatism. If there were a zero tolerance policy (as occasionally mooted by an idiotic politician in a misguided vote-winning exercise) then the courts would be clogged with people presenting calibration arguments.
I've never owned a single car that under-reads, and I've owned about 40 of all kinds of makes and ages. The same goes for several motorbikes I've had the pleasure of owning.
In my present car, with 4 brand new tyres, the satnav device disagrees with my speedo by a difference of about 4mph at 40; i.e. I could, if I chose to, do an indicated 50mph and be quietly confident of not being stopped.
I believe that manufacturers deliberate make speedometers that
over-read. This increases the safety margin.
Furthermore, as tyres wear down, the speedo will over-read more and more.
It all results in the likelihood that someone doing 80mph is likely to be looking at a speedo that's showing more like 90mph. For that flagrant disregard, no court in the land will be impressed by a whining pratt in the dock.
If you want to get to your destination earlier, then leave earlier.
If you want to speed, then accept the consequences.
And if you are speeding, then it's your responsibility to avoid collisions with cars that aren't.
For example, if you hammer through a 30 zone at 50, and I pull out of a side road into your path, and your skid marks show the truth of the situation, then who do you imagine is going to look like a ****?
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typing errors corrected