When inside a tunnel look how it is done in buildings, drawing footway in underground railway stations.
There they use level=

Buildings have building:part and building:levels

Bridges have man_made=bridge and bridge:part

When someone decided to use man_made=tunnel, are they going to use tunnel:part and tunnel:levels?
To set the outline of the tunnel.

Look at

Steps and ramps from one level to the other.

There is not a good sheme for tunnels! Yet.

How to use the same node in a building or a tunnel?

https://openlevelup.net/?l=2#21/50.77934/6.07464
Click in advanced mode on a door or room etc. From here you can import to JOSM.

level=-1-3

repeat_on !!!

This spiral ramp (building) goes to multiple levels in the parking building. In a way this is indoor tagging. Level tagging.

I understand it, but making a set off to draw a way is not correct. (maybe this is tagging for the router, how they implanted level in the shemes, a big question)

I also struggle with this.
JOSM have a nice level layering. :wink:

When a there is a busstop in a road tunnel, it is the same as with railway, should we do it the same?
https://www.openstationmap.org/#17.58/52.5248/13.36987/8.8/55