The Re-Volt Hideout

As the title suggests, enabling the double-sided flag for collision faces does not actually make the face double-sided. As an example, the roof of this overpass is set as double-sided:


But rain still passes through it (as well as cars if you teleport them on top of it):


(The normals are pointing downwards; the collision does work in this direction. The double-sided flag for world faces also does work as expected.)

Update: Huki has said that the double-sided flag is not implemented for collision faces and does nothing currently. This is thus not a bug. I'm leaving the topic up in case someone runs into the same problem.

You can still do a workaround and duplicate the selected faces and flip their normals to the opposite direction, remember to keep a minimal gap between both bunch of faces. If not, the car or any object will get stuck as soon as they collide with the faces

Thanks for the tip! I'll use that in my track.