Quote from Super_Pickle
I'm fairly sure you can't make the signal run upwards in a 3x3 column. To send signal downwards, you need at least a 2x1 area, meaning the tower needs to be stretched out one block. An upwards tower would look like this.
(If you need the signal inverted one last time, just stick a torch on one of the blocks that's higher than the repeaters.)
Although I don't think it matters what direction the signal is traveling. What do you need it for?
i'm looking for a compact method for sending signals down and back up for a multistage bridge
EDIT: without using redstone torches due to their unreliability in chunk updates