Train tunnel idea

[jchardin64]

Okay, first off I know very little about modding in factorio. I know how to change recipes and technologies around, not much more than that, so if this idea is impossible please forgive me.

It seems to me like it should be possible to make train tunnels work like this:
--Place a tunnel on the map the same way you build underground belts/pipes.
--The tunnel tracks are still on the same game surface, but invisible (meaning don't render anything except for the entrance/exit portals, and show the tracks with dotted lines when you hover the mouse like with an underground belt) Tunnels also don't interact with the surface tracks' signal blocks.
--When train cars are going over the tunnel track, don't render them and don't process their collisions. So the train can safely and invisibly pass through another train, a player, or any other object.
--The entrance/exit portal sprite has to be at least the length of one train car, drawn above the train layer so it hides the fact that cars are popping in/out of view as they pass through.

It seems like this should be possible. I mean, I've seen mods that make trains launch off the rails and fly through the air...

[vjbone]

https://mods.factorio.com/mod/traintunnels

[robot256]

Wube fixed a bug a while ago that enabled collision-less trains, because it creates too many edge cases for them to support. You can make tracks that let trains go through objects, but they will still collide with other trains and there is no graphical accommodation.
https://mods.factorio.com/mod/non-colliding-rails

Renai and the currently available TrainTunnels mod work by deleting and recreating every wagon every time it passes, so they are complicated, inefficient, and more prone to glitches. So, it would be possible to literally copy Renai so the ramps went "down" and the in-flight trains were invisible. That's about it.