I especially like the option to build undersea tunnels
Is it possible to make a patch where the undersea tunnel is built automatically if the tunnel-exit is a shore (i.e. if the entrance is at level 0, and there is no possible exit, then it will look for the first possible exit on the next shore). Then there will be no need to use the ctrl-button, and unrealistic tunnels between mountains will be impossible.
( o/\...... /\o )
IMO, that kind of undersea tunnel is more realistic than previous attempts to have several levels below sealevel, as in RL, the entrances to these tunnels are usually at or above sealevel.
Such a patch may also easier reach trunk, as it can be made much shorter, since all the signal stuff can be omitted.
Allowing trains to pass each other inside a tunnel, is IMO a bit unrealistic, so I would not play with that option.
Finally, I have a few extra thoughts about such tunnels:
If undersea tunnels are made, then how should one decide whether to build a tunnel or a bridge? obviously, this depends on the depth, and on geological conditions, which are not part of the OTTD world. Is it possible to simulate that the undersea tunnel goes down a few levels, and then up again, in the calculation of how long time the train/rv uses to go through?
Where I'm from, we have a few undersea road-tunnels. These go down to 200-300 meters below the surface, descending at 8%, which really makes loaded trucks slow down on their way up.
A theoretical depth can maybe be calculated based on the surrounding landscape. The landscape under the sea can often be guessed from the steepness of the shore. (But of course, having some undersea levels would be the best.)
happy new year