OR37
Lane Division outermost, innermost
When we look down the Road Segment ahead, we see a number of Lane Divisions starting with an innermost Lane Division progressing to an outermost Lane Division. Our Lane Division IDs are not ordered, so from outermost to innermost near our vehicle we see 6,3,9,7. Further up, two lanes merge (7-9) and (9-3) to form (7-3) and an inside turn lane forks to form (8-7).
If we want to get into (8-7) to make the inside turn, how do we know which Lane Division to cross first? We need a way to determine that (8-7) is to our inside. Since the Lane Division IDs are not ordered, so we can’t use them to figure it out. We also have the problem that (8-7) isn’t even in our current Lane Configuration Segment. Driving Lane Order numbers (Lane 1, Lane 2, etc) don’t work either since they vary by Lane Configuration Segment. What we need is a total lateral position ordering of Lane Divisions across the entire Road Segment (irrespective of Lane Configuration Segments).
Fortunately, the Position (lateral distance) of each Lane Division give us just that. Even though actual distances may vary as lanes narrow and widen by small amounts, Lane Divisions never cross over each other! So we can always use the position ordering to determine whether we need to move to the inside or outside to reach our objective Driving Lane.
Driving Lane Order.Position _in_ Road segment
ascending - innermost