Yes, I know the ones you mean; we have some close to where I live.
Trouble is, some drivers treat them like Gatsos and still pull on the anchors even if they are driving at the correct speed already. Driver passes by at the correct speed and the sign flashes. Result panic. Flash not caused by said driver but by someone following in a supposedly faster vehicle (perhaps only doing the limit in any event, the signs are not that accurate) that is likely to plough into the back of the panic breaker.
I have seen the signs near us flash with noting moving towards it other than tree branches waving in the wind (or was it me walking towards it!) Perhaps it's a good job it isn't a Gatso or I'd get a ticket for walking to fast. On the other hand, often it doesn't flash at all to some vehicles passing well over the limit. One word sums these up... useless. And of course they are paid
for by the local residents driving up council tax. One has to ask how and why should a local councillor be able to have these signs put up solely at his/her whim and fancy without any local consultation or formal planning consent with notices in the paper etc.
Another of these flashing signs is next to my turning advising of a cross road junction. I see it lit when nothing is on the road at all! All it does is unnecessarily distract me as I turn out onto the road.
God help us, we've managed for over a hundred years without these things flashing. Are they really necessary to make the roads safer? Do they actually make the roads any safer? Given that they panic the law abiding and ignore the law breakers they are little short of useless, if that.
Further, a flashing sign may well distract a driver enough for him/her to not notice a driver pulling out of their driveway. This has happened by our nearby sign.. the said councillor immediately blamed speeding, of course, and promised more flashing signs only he wasn't aware of the facts. It was a vehicle exiting a driveway run into by a passing vehicle, right next to the flashing sign. No speeding involved at all.
Photo of location here:
http://www.scarborougheveningnews.co.uk ... 3382975.jp
only this was of another accident at the same spot the previous year.