Comment by msm_
1 month ago
>Also, speed limits in some states can't be enforced from 0 to 5mph over the limit.
In my country that's also true (with marigin larger than 5mph), but my understanding is that that's because the measurements instruments (laser-based speed meters) are not perfect and it may be a mistake and not actual speed limit breach.
Some methods of measuring car speed don't have this limitation, like range-based measurements (check time when car enters road segment, when it leaves road segment, and make sure the average is under the speed limit).
And less so now, but also speedometers. As I was growing up in Australia, there was a legislated margin of error of 10% for speedo inaccuracy. And I want to say some time in the late 90s, early aughts, that margin was changed to 3km/h across the board. I don't know how that interacted with speed camera tolerances.