However, they are rather useful for those who have restricted vision or are blind to identify just where the pavement stops and some other place begins - I believe the knobbles are the size they are in order that they can be positively identified by someone using a 'cane' (or their feet!) before they reach the kerb edge. I think they're also along the edge of many rail platforms now - I seem to recall them at Paddington.
I appreciate that, but as Chris said, thats not much use if you slip over
Bike tyres fit perfectly between the knobbles, so with a bit of decent positioning, they shouldn't be a problem!
THATS the problem - the bit between the knobbles is the slippery stuff! If the knobbles were closer together and less smooth area was there, they would be much less slippery - but perhaps not as much use to partially sighted people.
I do agree with the footwear though - some shoes are incredibly slippery on certain surfaces when its wet, yet others seem to be perfectly fine. When I was walking to work a few years ago, I could not cross a particular road - everytime I ventured out I slipped over (it was icy, not wet) - yet all the yoof just walked across. I couldn't fathom out if it was my shoes or the "fear" factor that I had in my head I would break my arm just before Christmas when I went flying! Either way, as soon as I did fall over I retreated home and worked from there instead
I do wear hiking shoes as I walk to and from home<->station<->work and have tried a number of brands, but still find most slippery. I think our rain is too wet, like our snow
(as strangely enough, I didn't slip when walking around snowy Sweden in the same shoes!).