Many, many years ago, I read a book about a road that travelled through time. It was a physical road that, travelling one way took into the future, and the opposite way took you into history. People travelled this road in a variety of ways depending on where they got on - from walking to fantastic machines from the future. The main character was being hunted by various assasins (one named Timyn Tim?) and carried with him a book that housed or was home to a sentient being/computer that he called “Leaves.” The main character experienced some sort of transformation at the end - becoming a… dragon of some sort?
That’s about all I have; ring a bell, anyone?