'Perceptual countermeasure'.mangocrazy wrote: ↑Fri Nov 25, 2022 2:50 pm I did ask about the questionable value of putting raised rumble type strips on the entrance to roundabouts when that could only impair braking efficiency and he wasn't able to justify it.
Like the ridged lines on the left edge of dual carriageways and motorways, the vibration is designed to wake you up if you've lost focus or you can't see the edge of the road or roundabout in fog, spray or heavy rain. And approaching roundabouts they get closer together the closer you get to the junction, to instil a sense of urgency and a sense of getting close to the hazard.
AFAIK, they start early enough and far enough apart that a driver can still brake from speed.
My beef is with their use on curved roundabout approaches which force a bike to lean over as you cross them. Even more useless are the strips that many local authorities persist in using on the approach to a rural 30 limit. They too are often found on curves, sometimes quite sharp ones.