[0.13.9] Splitter bleeding in to underground belt

[butanefuel]

I've only seen this recently so I believe it to be new.

I have a set of belts where one end of a splitter is at 90deg from the entrance to an underground belt. This splitter appears to be 'bleeding' material in to the underground belt as if they were connected. Moving the underground belt entrance stops the bug from happening and re-placing starts it again so I believe it is the splitter/underground combo.

A save is attached showing the bug.

The image below shows the general setup as well as the results

Results

Capture.PNG (421.84 KiB) Viewed 1996 times

[Koub]

They are in fact connected.

Surrounded in red

Factorio - Splitter underground belt junction.jpg (96.87 KiB) Viewed 1993 times

The left lane of your left splitter output (as seen on screen) outputs just before the underground belt entrance.
It's intended behaviour, but at the moment, the graphics don't show this as possible. There's currently a discussion/suggestion about that.
[Edit] there it is : viewtopic.php?p=191961#p191961

[TruePikachu]

This behaviour is used in a lot of complex arrangements, so it is useful to learn. For instance, here I use it to seperate copper plates from iron plates out of my smelting setup:


Anyway, technically not a bug.

[Koub]

I'd say it's a graphical bug. Sprites tell you something that isn't reality. They tell you you can't side insert into an underground belt entrance, albeit you can.

[Klonan]

I think it is fairly clear that this isn't a bug, one side of belts can move onto the side of an underground belt, and it has pretty much always been this way

[butanefuel]

They are in fact connected.

Surrounded in red

Factorio - Splitter underground belt junction.jpg

The left lane of your left splitter output (as seen on screen) outputs just before the underground belt entrance.
It's intended behaviour, but at the moment, the graphics don't show this as possible. There's currently a discussion/suggestion about that.
[Edit] there it is : viewtopic.php?p=191961#p191961

Thank you Koub, this was clarifying.

I will agree this isn't really a bug. The behavior is consistent with other belts. I believe there is room for improvement in telegraphing what underground entrances can and can't interact with but that's for a different forum.