I think these signs are probably quite expensive to implement, because this is the first one I’ve had a good look at. It informs drivers of their speed:
… and then tells them off if it’s above 35mph:
… and says thank you if they do:
Wonder how long the effect lasts? Has there been any research on this? (TRL perhaps?). Can’t imagine it’s that effective, but might be a bit useful.
Anyway, this example was on a road close to where I grew up. The very road in fact, that was sufficiently dangerous to ensure that I was not allowed a bike as a child. It doesn’t seem to have got any better, though there is a painted cycle lane along a random length of it. And I did spot one or two brave middle-aged blokes on heavy-looking mountain bikes. Outside the likes of Bristol and London that seems to be what it’s like.