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.)
Very common on inverted cloverleaf interchanges
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.
I don't care about total length of road on map, why would anyone? I only care about segment count, junction complexity and naming complexity. Two-way ramps are typically the simplest regions of the ramp, straights and simple bends. When we had a splitting tool I would adjust geometry once, then split. I've made a request of Waze to see if we can somewhat duplicate this functionality. Why do we care about flaky GPS on close ramps? There is only one solution to a ramp, you get on, you get off. Unlike split roads.
Every junction is a calculation that the routing server has to make. One-way to two one way is one decision. Two-way adds three decisions, at least. Also more ways for the editor to get it incorrect.