[scorpio_rocks]

In game terms a "stream" is water less than a hex wide, a "river" more than that.
Whatever you choose to call it (brook, beck, creek, river, canal, etc) it is up to 50m wide and is significant enough to be an issue which is why it appears on the game map. If it had shallow banks and was a few inches deep it wouldn't appear on the game map...

The secret is speed - or rather lack of speed! vehicles moving slowly are MUCH less likely to become stuck. Move vehicles up to the hex before the stream in 1 turn then move a hex at a time to cross the next turn. Similarly for moving along a road, or not. If you move 5 hexes in 1 go the software chooses the "path of least resistance" ie the easiest/fastest (in terms of movement cost) so will in that case always use a road if available. If you want a specific route to be used move in smaller increments (even 1 hex at a time).