We have some very odd shaped and slippy “north shore” style bridges on one of my fave trails. Put there by the local forestry bods to help folks walk over gaps and small gorges through the woods.
They are cut down trees, round with branches cut off, not sliced through to create a flat surface, noooo that would be too easy, they’ve left them log shaped and they are both very odd to walk over and ride.
When wet they’re a nightmare.
I’ve yet to understand the logic, so too the folks that have so far broken ankles and twisted knees on them. 🙄