My main reason for avoiding two way ramps is that each direction usually has very different names (e.g. "Exit 123: blah blah" vs. "to highway blah N"). A two way segment should be unnamed so it picks up the proper one-way part that it (hopefully) connects to. But unnamed segments often get an eager editor trying to assign a name then you get confusing instructions.

That said, I am sure I have left some two way ramps in place where I have edited.

I just checked all the pike exits between 95 and 290. Only 290 and 20 have separate ramps through the tolls, the rest suffer from the same problem. Also, some of the Millbury ramps are locked:

https://www.waze.com/editor/?zoom=4&lat ... 1,22938077

So, I-95, Natick, Framingham, I-495, and 122 Millbury would all need to be split. Probably more.

Are we sure this is a good idea?

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

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.

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.

Fewer segments? Seriously? Nearly every ramp diverges at one or both ends. So a two-way joined to 2 one-way is three segments. Two one-ways from start to finish is two segments. Plus you've taken away all sorts of decisions and penalties that the routing engine has to apply.

That is the crux of the difference between ramps and roads. Ramps almost always diverge. I've done lots of ramps each way. Editing is so much simpler without two-way ramps. I don't need to address 'symptoms', they just flat-out work, with virtually no URs. Why are we even debating this?

Yep, an exception. But I see most experienced editors doing it already.

Let's put it this way. You can make it work either way. But the easiest way to be sure of your work as an editor, splitting ramps is the way to go. Every extra junction that needs to be set with the correct turn restrictions, and checked for correct commands is another place for you, or a newb to screw up routing.

My life got a lot simpler when I stopped trying to make two-way ramps.