Quote Originally Posted by Cambyses View Post
1. How would the AI handle it?
2. Can a river be navigable and still have bridges/fords?
3. Are bridges over certain rivers meant to be realistic or actually just representative of ferries?
4. Can river access be limited to certain types of ships?
5. If this would require a lot of work, would it be worth it?
Viking longboats are not comparable to triremes, so their example doesn't count. The lower Nile certainly was navigable by triremes and bigger, though.

1) It will simply treat the rivers as sea. It probably won't understand that it can be blocked by putting a ship there, but it doesn't understand how to block mountain passes either.
2) No. Well, technically, the team can create landbridges like for example at Byzantion, but I suspect that will require the river to take an odd shape.
3) Both, I suspect. I don't think there were bridges over the Rhine and lower Danube until the Romans built them. In any case, there would have been more crossing points, so these must have been the ones big enough for an army,
4) No.
5) No, but it would make the rivers look weird and be uncrossable for armies.