Ever noticed how the white road markings are really slippery when wet?
I remember discovering how slippery they can get when riding my bike to school in the wet. I would always ride along the bike track that had a single white line running down the centre of it.
One day, as I was ascending the one significant hill on the trip to school, my tyres touch the line as I applied power to the wheels through the peddles. I soon found I was struggling to stay on as I contended with the sudden loss of friction, which was quite a surprise.
I don't ride my bike much nowadays, but I still experience the slipperiness as I take off from the traffic lights in my car and feel the wheels start spinning as they try to accelerate over the wet line.
The irony of all this is that zebra crossings are painted out of the same stuff. The same slippery-when-wet concoction that my bike tyres slip on and my car wheels spin on also makes it hard for pedestrians with certain types of shoes (like uggboots) to stay upright on.
So much for being the safe place to cross the road.