For the shared left situations, I've typically been using one segment for each purpose, like here: https://www.waze.com/editor/?lon=-82.90 ... TT&env=usa

It eliminates the confusion of someone seemingly being told to turn onto the other side of the road when they're actually going to a mall parking lot or some other street.

It could be accomplished with two stacked segments using the same nodes and tailored turn restrictions, which may look better on the map, but this is easier for other editors to see and understand. I haven't looked at this in the client to verify.

jemay wrote:Observation... The landmarks, why don't you use "Junction" (if you name it, it will appear on the client if is big enough.)

I believe they're being used here only for editor reference purposes.

HA! How embarrassing. Thanks.

I thought jughandles were in the Wiki already, but I couldn't find it yesterday.

Regarding the double segments sharing an origin node, yes, I think that's a good idea. I'd prefer not to have them share an end node, though, for editor visibility and because of the documented problems with segments that share both nodes.


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Very good post. Sums it up exactly.

It's not a "big green sign" but it is a sign. Freeway entrance ramps throughout the country often don't have big green signs or even green signs at all—just a little shield and a little arrow. Still, we name them for the sake of consistency.

So whereas some Michigan left setups don't have green signs, many of them do. For the sake of consistency through the metro area (and... the state???), we name them all.

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In the New Orleans area for the non-Michigan-left type turnarounds, we use the street type and "U turn" for these. However, many of ours have signs that say "U TURN"—almost all of them in the suburbs. Although the U turns in the city are typically not signed, we name them too, for the purpose of consistency within the metro area.

In Michigan, however, I've never seen one of these signed as "U TURN" or anything like it, so I suppose I'd continue to leave them unnamed. I don't really know what you guys would call them up there, although I've seen a few around named "Turn Around".

davielde wrote:Just out of curiosity, what are the documented problems with two segments sharing nodes? I can imagine routing problems where the one with faster average speed or shorter distance may be preferred, which could particularly mess with drivers if both have separate street names, etc. I haven't seen this anywhere on the map yet where it was intentional. Any other issues?

Yeah, there's some kind of bug with the routing server that has trouble differentiating between the two.

I don't have time to track down any of the relevant threads, but essentially, imagine two segments that start at the same node; one goes to the left, one goes to the right, and both turn back inward and meet at the same end node.

I've seen URs where the purple route line will show that Waze gave the route on the left segment, but the black box shows a "keep right" instruction. Also, Waze seems to have some confusion picking the actual better of the two segments. Two particularly egregious examples: a truck weigh station drawn as a single parking lot road segment off a freeway; a drive-thru drawn as a single parking lot road segment off a minor highway. In the latter example, if I recall correctly, Waze gave the route line through the drive-thru but gave no turn instruction. It's just real weird stuff.

To use the example posted by davielde:

A user needing to turn around will be told first "Turn left, at Jackson Rd E, to Wagner Rd S.", and then "Turn left, at Jackson Rd." A user needing to turn left onto Jackson Plz, on the other hand, will be told "Turn left, at Jackson Plz."

If we combine the segments, we need a compromise. If we name them according to the Michigan left rules, a user will be told "turn left, at Jackson Rd E, to Wagner Rd S" even if he's just turning onto Jackson Plz. It's confusing and leads to an expectation that they'll be turning right. On the other hand, if we don't name them, we get behavior inconsistent with all other Michigan lefts, and we lose all the benefits of having a named Michigan left.

1) Nah, turns onto no-name segments take the name of the next named segment, as long as there is another next named segment. If the turn were onto a no-named segment then into a no-named parking lot, it would just say "Turn left."

2) The problem isn't necessarily that the one "turn left" instruction would be confusing, but the fact that the instruction would start with "Jackson Rd E" would be confusing. Maybe it isn't that confusing, but it would also make it difficult to know which lane of the Michigan left to be in, in situations where, say, the left lane is left-turn-only and the right lane is left-turn-or-go-straight.

Sure, sounds good. Let me know when it's up, or better yet, post it here so I can proof it.

Very good. Thanks!

The naming convention was designed specifically for Michigan. Not every Michigan left in Michigan has a green sign, but many of them do, enough to make it desirable to implement them throughout the region for the sake of consistency.

I don't know how well it'll work in other areas, though. None of the Michigan lefts in the New Orleans area are signed like the ones around Detroit—rather, they have the same "U turn" signage as all the other U turns, so we label the segments "U turn" like all the other ones. Here, the difference between a U turn that's used as part of a Michigan left and one that isn't is the road type.

In other areas, I think I'd recommend building a convention based on the green sign, emphasizing the importance of the second "to".