harling wrote: So you are correct that using two-way ramps sometimes results in one additional segment. (The only time it reduces the count by one is when you have a single two-way segment, which is rare.)
harling wrote:What is reduced is the total length of roadway on the map: replacing two very close, parallel stretches of road with one. That means one segment to adjust to get the geometry right instead of two; one segment for a sometimes flaky GPS to snap to instead of two.Plus you've taken away all sorts of decisions and penalties that the routing engine has to apply.
Such as? Two-way segments maintain independent speeds for each direction, and as I understand it, junctions keep track of the cost of each segment transition separately.