I’ve been out up rivvi tiday, if you head right to the top of coal pit lane there’s a riding school with a trail running round it on the left. It looked deliberately spread around where loads of self tapping wood screws. I picked up what I could see just keep your eyes open. I suspect it’s to discourage off roaders, dirt bikes etc. Certainly wouldn’t want one in a dog’s/ horses foot..Was limited to the section of trail in red (assuming I link pictures properly).

I ride that section all the time (It’s not actually Rivvy, it’s part of Smithills Moor)
Theres a short steepish climb/descent to the right of the section that you’ve highlighted – there were steps there a few years ago but they have since been removed.
Never found any screws there, but i know it’s really popular with horsey types.
I’ll keep my eyes peeled next time i’m there – tomorrow hopefully.
Cheers

That’s the section yeah

How bizarre.

I know exactly where you mean, can’t imagine then ending up there by accident but also can’t quite see what’s intended.

Never seen motorbikes up there myself, have you?

I also know where you mean, and agree with chakaping that its and odd place to find them. It looks like half a box you’ve got there!
MTB’s or motorbikers aside given the length of those things if a horse were to embed one it its foot it could quite easily be an horrendously expensive hospitalisation trip, or at worst cause a fatal infection.
Is there a horsey forum for the area around Rivi? Might be worth dropping them a line.

I’ve passed it onto horsey friends. It is a bit odd and very localised but there were no new fences or repairs that I saw and quad tracks that only went as far as the screws. It could be an accidental thing but seems very odd