Can I detect (and correct/destroy) errant carts?
So this happens a lot:
Minecarts desynch from the track and glide beside it at weird angles. Can I detect a cart doing this somehow in an automated way so I can knock it back on track or redirect the rail for disposal?
Best Answer
Rather than detecting a derailed cart, why not ensure the cart doesn't derail in the first place? The derailing comes from going too fast into a corner.
Given the latest version of Minecraft, "unpowered" powered rails slow down any cart going over it. Assuming you're going one-way only, place some "unpowered" powered rails (judging from the photo you'll need maybe 3) before the turn, then place a powered rail after the turn to get the cart moving again. You'll lose a bit of your momentum, but you'll stop the headache of derailed carts.
If you're working in both directions, you'll have to work on redistributing the spacing of the powered rails coming up to the corner to reduce the speed naturally; given your current powered rail spacing (you've got your powered rails really close together), you could take the closest 2/3 on either side out; you'll need to experiment with that, though.
The easiest to understand bi-directional rail system, though, is two tracks or a looped system to use the unpowered powered rails as suggested initially.
Strictly speaking, in vanilla minecraft I've never seen a method by which mine carts can be "detected" once they've left the rails; pressure plates might work, but I've also never seen a method by which mine carts can be pushed back onto the rails. As for "redirect[ing] the rail for disposal", just leave it; it'll despawn after 5 minutes.
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