I'm feeling a bit silly posting this here but I've checked for this feature and can't find it other than clicking the upgrade button on a transport building itself.
Often, when I plan a factory, I don't care right away for the transport level that I'm laying out... Using low level belts and pipe is great since the upgrade tool works wonders (!!), but when I'm stuck on high level transport and I don't need to spend all the ressources, a "downgrade" tool or feature similar to the upgrade one would be really nice, more QoL.
In short, I'm just looking for a shortcut to upgrade OR downgrade easy and I didn't seem to have found one programmed in the game.
Thanks

this exists, in the mass upgrade tool you can select lower tiers

JustADragon wrote:

this exists, in the mass upgrade tool you can select lower tiers

I know, but it's not as convenient.
My idea is quite simple since it's already exist for the pause tool... Click with the upgrade tool and it goes up, hold shift and click and it goes down. For some reason, it's not an option in the game already.

Good idea.