4 ms·

The threshold is generally accepted as 10% over, so 77mph on a motorway. However, I only know that from hearsay, so take it with a pinch of salt.

richmarr 11y ago
My understanding was that the 10% margin is to defend a fine or prosecution bearing in mind the error bars of the camera and the vehicle speedometer. Again, no credible source. Dad, if you read this I didn't mean it, you are very credible.
maccard 11y ago
That's what I'm lead to believe too, although I have no facts to back it up.
dazc 11y ago
I think it's 10% + 2mph? So on a motorway or dual carriageway the limit is really 79. It used to be generally accepted that you were safe doing 80 mph but with the proliferation of average speed cameras people are a bit more conservative. 10 years ago it wasn't unusual to see people doing 90 - 100 on a motorway - now it's rare.
- jon-wood 11y ago
  > So on a motorway or dual carriageway the limit is really 79. Nope. The limit is really 70, however to take into account possible inaccuracy in your speedometer or the traffic camera, there's some leeway in place. If you start assuming the limit is 79 then if nothing else, you no longer have the benefit of that leeway. How sure are you that both your speedometer and the camera are 100% accurate?
Already__Taken 11y ago
Facts: My friend just gone done for 48 in a 40. They told him the law in that county was 10% + 3 which would have come to 47. Off to a speeding course he goes. Made up: I thought the 10% came from the rules the speedometer is calibrated against which are +10% -0% i.e. Your speed will be 30mph but you could be doing 27. You will never be doing 31. I guess the plus number is whatever the council have chosen to enforce. Another person from the country thinks it's 10%+2 edit: Here you go, it's a more nuanced than above. Europe's law. Read Page 8 - http://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/r039r1e.pdf http://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/... Displayed (V1 ) and the true speed (V2) 0 ≤ (V1 - V2) ≤ 0.1 V2 + 4 km/h

richmarr 11y ago

My understanding was that the 10% margin is to defend a fine or prosecution bearing in mind the error bars of the camera and the vehicle speedometer. Again, no credible source. Dad, if you read this I didn't mean it, you are very credible.

maccard 11y ago

That's what I'm lead to believe too, although I have no facts to back it up.

dazc 11y ago

I think it's 10% + 2mph? So on a motorway or dual carriageway the limit is really 79. It used to be generally accepted that you were safe doing 80 mph but with the proliferation of average speed cameras people are a bit more conservative. 10 years ago it wasn't unusual to see people doing 90 - 100 on a motorway - now it's rare.

jon-wood 11y ago
> So on a motorway or dual carriageway the limit is really 79. Nope. The limit is really 70, however to take into account possible inaccuracy in your speedometer or the traffic camera, there's some leeway in place. If you start assuming the limit is 79 then if nothing else, you no longer have the benefit of that leeway. How sure are you that both your speedometer and the camera are 100% accurate?

Already__Taken 11y ago

Facts: My friend just gone done for 48 in a 40. They told him the law in that county was 10% + 3 which would have come to 47. Off to a speeding course he goes. Made up: I thought the 10% came from the rules the speedometer is calibrated against which are +10% -0% i.e. Your speed will be 30mph but you could be doing 27. You will never be doing 31. I guess the plus number is whatever the council have chosen to enforce. Another person from the country thinks it's 10%+2 edit: Here you go, it's a more nuanced than above. Europe's law. Read Page 8 - http://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/r039r1e.pdf http://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/... Displayed (V1 ) and the true speed (V2) 0 ≤ (V1 - V2) ≤ 0.1 V2 + 4 km/h