smeggy wrote:
Really? For all Lidar, Radar cameras?
You are, of course, right and I am wrong…shouldn’t rely on this ageing memory when legislation/ regulation changes are so voluminous and complicated.
My beliefs stemmed from the early Gatso HOTA (which was for ‘in excess of 30mph’) coupled with the earlier requirements that

zones had to be self limiting – so, by extension, with the lowest ‘natural’ limit

my assumption for measuring devices generally (ie – not that they couldn’t read below a limit but that they were not approved to do so). Reading up on more recent rules/regulations/hatos gives the lie to my previous postings – and with that comes my apology that I may have confused or misled anyone.
Interesting, though, that speed restriction practices in

zones are simply to ease the burdens of the BiB:
DETR Circular 05/99 wrote:
The key to a successful 20 mph zone is to have in place speed reducing features of a significant number and appropriate design to be able to reduce the speed of most traffic to 20 mph or less without the need for police enforcement