Only 1 tunnel can be used, I'm the only one who has this problem ?

The "snapping point" is incorrect. The asset snaps to road sides by its outer edge - not by the built-in roads. One must draw an extra parallel road just one unit away (as seen on pic 3) for placement, that can be removed afterwards. It makes placing this somewhat complicated...

This asset is great! I think it's important that it's completed.

Personally, I'd expect we all want the lanes to be changeable especially for the Network Exentsions Mod (alternate roads).

This is a very cool concept of getting people into the Metro without them having to cross the street. I also had some ideas about for this, but I never started working on an asset. I might try recreate this in some way for Fishbus'-Metro stations (because I use them for my own cities and I'm definitely not good enough in creating my own models) in the future even if it's made some months ago.

Can you add a picture showing the underground pedestian paths? They must connect up all together in some way and then to some +-8m 'loading paths' at right angles across the centre line of each platform.

If you want to stop pedestrians getting 'Harry Potter' capabilites you need to make the pedestrian paths more than -9m under the roadway.

The built-in Mtero has paths at -4m and this does seem to cause the game engine problems in some cases.