Sadly bike lanes become unusable at times. The ones that run parallel with roads often get all the debris from the road thrown onto them. In autumn the leaves gather there making it very dangerous as they can hide holes and even large objects like bricks. Not to mention leaves are very slippery when wet.

As a road cyclist, it pains me to say this but cars actually clear the roads from debris due to the sheer volume of cars and their much wider tyres.

I live in quite a rural area now and the back roads are full of mud, stones and sand from farms fields and trackers.