Hmmm.. amazing, I never thought of this before. I never been captured while travelling on roads or ferry ride before. Did the chance % go up suddenly?
Well, characters normally travel with soldiers. So long as you have at least 1 healthy soldier, you cannot be captured while traveling.
Also, you can only be captured while traveling when in enemy lands. i.e.: traveling through a realm with which you are at war. And how often do you travel through enemy lands with no healthy solders?