A) Carl Jung didn’t cross the road. He followed the road, to individuation.
B) Carl Jung didn’t need to cross to the other side. He could get to the Other Side with active imagination.
C) To integrate the other side. (Thanks to Peter Lakanan, from the comment section)
D) Now that’s an interesting question about the symbolism of crosses and roads. As Jung himself said when asked about a dream of a mastodon he once interpreteted
The doctors of antiquity and of the Middle ages used dreams for their diagnosis…. It is really a matter of special experience…. The dream you mentioned was a dream of a little mastodon. To explain what that mastodon really means in an organic respect and why I must take that dream as an organic symptom would start such an argument that you would accuse me of the most terrible obscurantism. These things really are obscure. When I speak of archetypal patterns those who are aware of these things understand, but if you are not aware you think, This fellow is absolutely crazy because he talks of mastodons and their difference from snakes and horses. I should have to give you a course of about four semesters about symbology first so that you could appreciate what I said.
(With this statement from Jung, we could all be scared away from the trying to understand dreams…. In general, dream interpretation is not that obscure.