For me, the Soul's Road is more of a timeline, because that's the way I think. It's a graph, starting at day one, and continuing until it stops which, depending on the philosophy you subscribe to, could be before, during or after death. In any case, the road upon which I walk is, to the best of my knowledge, linear. Oh, but that may not be true. According to quantum theory, there are an infinite number of alternative roads I could have taken; one for each decision and outcome ever made in my life, if I understand it correctly.
Revised definition: my Soul's Road is the path upon which I walk, singled out among the infinite possible paths of the road before, at and ahead of me, because I have/am/will walked/walking/walk it.
But that's confusing. How about "the road upon which my soul treads, which is singular and unique." Now I'm getting into Scott McCloud's "what are comics" territory, but the idea is sound. While the overall effect of the infinite possibilities inherent in human life would, to my mind, look something like an enormous snowflake - with the "center" being where you are now and an infinite number of branches stretching in all directions - the road analogy still works, since the road will still move in a linear fashion through the snowflake of possibilities. That is, unless we invent time travel or a way to jump through realities like Ace Rimmer (see Red Dwarf.)
Re-revised and simplified (again) definition: My Soul's Road is the path which I have chosen, out of the infinity of paths available, to walk at this time, in this life, and is a map of where I have been, where I am, and where I am going.