1. when i build busstops on public roads other players can (and do) place roadsigns at the same tile where my busstop is situated (private road barriers, oneway signs etc. make the busstop unreachable) - i can't even delete my broken busstops because then the game tells my that the structure is from another player
I plan to look into such problems in the future. A similar situation is with a public stop on your way, you cannot delete your own way. Another such situation is your way-objects placed on a public way with a public stop, you cannot delete or make public your own way-objects in this case.
For the case of signs, I think they should possibly be disabled on public ways to stop this. They are public so using signs to restrict use seems kind of contradictory.
2. some players connect their roads to my tunnels, when they do it i can't remove my own underground roads that are adjacent to this intersection
Need an example map demonstrating the problem.
in pak64 there is no "end of choose" sign for roads, some players put choose signs on public or other transit roads and there is no way to tell bypassing vehicles that they shouldn't search for another stop
Would be solved by solving problem 1 by disabling private signs on public roads or making sings on public roads public and able to be changed by anyone. Who uses road choose signs anyway?
A bigger problem is a lack of end of choose sign for mono-rail in pak64.
4. imho at tiles where roadsigns (private barriers, oneway, speed limits, ...) are placed it should not be possible that other players connect and create intersection on that tile (it is causing strange effects sometimes)
Best seen in airports where one can use a one-way sign on an intersection. The correct behaviour in this case should probably be to throw an error when trying to make an intersection or to allow those signs on intersections with customizable, well defined behaviour.
For (2): This can only happen if part of the tunnel is made public, and then another player can connect. Are there other possibilities to get to this situation?
Inside a road tunnel you can connect to it as any other player like normal road. However the intersection should still be owned by the original player and should still be able to be deleted.
I am guessing but maybe if a tunnel mouth is right against another player's road then it breaks because there is meant to always be 1 tile beyond the mouth underground. Trying to delete the intersection then might throw a permission error as the tunnel mouth cannot be deleted. However a demonstration map is really needed to confirm this, and the solution would be to change the tunnel moth logic to either allow no following tunnel tiles or to force ownership of both tiles (not allowed to take ownership away from other players so the tunnel build would fail).
(3) Maybe vehicles should check the owner of the sign? So vehicles will not react to choose signs of other players and simply pass.
It is needed for rails to operate correctly. It is completely possible to drive trains over other player's tracks.