underwater tunnel ?

[BR|sCip]

hi
just want to build a underwater train connection but these tunnels are full of water and even connecting them is impossible.
any thoughts ?

[arthurlewis]

Have you built deep enough?

[sethtriggs]

I needed a loooooooooooooong approach for a water tunnel (which is realistic) because they have to clear the very bottom of the channel. I think i got to -30 meters and was able to cross. There's some fiddliness with underground building so just keep trying!

[warbeetle]

Yep. start from the surface next to the water and work your way down in 10m steps - along rivers and coast -20 will be the minimum; -30/-40 the average or even deeper. Look at the underwater surface - if it has deep trenches under water you might consider using the terrain editor tool to avoid having to go too deep.
If you start from land the game will show you when you break the surface with your tunnel.
Watch out for cables and pipes - they will block certain heights forcing you to go even deeper under them. Once you found the right height you can also start under water.

[Aieonae]

Make thing simple pulling underwater is more a 3 step process.
1) pull the underwater section first, make sure it’s a level section underwater, leave sufficient space for 2 and 3.
Make it -50m preferred, so that seaway, HV cables and pipes wouldn’t be an issue. Since most players go -10m for those.
2) pull slope from underwater sections on both end to -20m to land, the ramp will be long so prepare for it.
3) tie up the final sections on both end from -20m to 0m however you want to fit the city grid on the ground.

Worth noting:

have underground intersections not underwater ones, as you cannot build roundabout underwater for the moment.

Use sections at 0m,-20m and -50m as adjustable heights as slope in this game are very not snappable. Notice the cursor change from underground road round section to a cross hair for connectiviy!

[BR|sCip]

thank you all 4 response :)
finally i got it