access permission are not working, for some reason.
I would suggest only connecting ship ports with ship ports, at least for this era. Road connections are too unreliable and low capacity for joining networks.
For connecting, it would be nice to ask or leave messages in chat or signs.
Personally, I don't mind too much for unannounced connections, but would prefer them to be placed at a hub, since branch lines tend to get overloaded easily without user interaction.
City claiming... I would suggest first come, first serve... But if you have to go through a city someone else is serving, try not to use the same roads, because there may be unexpected blockages. Also, try and work out a connection with the other player, because walking is enabled and may cause overloading problems if the connection is not placed strategically.
Not that one can't play aggressively at later stages
Typically, I find cooperation is good in the beginning, but not entirely necessary at later stages in the game.