Factorio Forums

Underground belts can usually be placed on top of other underground belts, like lots of other stuff such as inserters and regular belts, to re-orient it. This doesn't work all the time, though. Specifically, it seems that you can place underground belt, replace it with another underground belt going the other way, and then you can't replace that with another one going the first way. Just have 2 underground belts in your hand, and click 3 times on a tile and you will see what I mean. Yes, there are so few bugs in this game that I actually find tiny inconsequential ones like this.

Literally Unplayable!

Thanks for the report,

I can confirm the behaviour described, you can only fast replace a underground belt 1 time, clicking on it again will do nothing:

Might be slightly related to the .direction of the ug belt

if you click-drag to lay down ug belts all of them will have the same direction.

Fixed for 0.14.10.