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Re: [New Page] Median U-turn intersection

Fri Mar 21, 2014 12:19 pm

CBenson wrote:I have driven them but had never heard them called anything.

Give it twenty years, and there will be nicknames locally used for those too :-)
I suppose "Michigan Left" really is best then, with possible continued mention of at least some of the variants on the page itself. True synonyms like "Arizona Parkway" or "Boulevard Turnaround" could probably be removed altogether and just exist as redirects.

Re: [New Page] Median U-turn intersection

Fri Mar 21, 2014 3:23 pm

One thing that could be added into the wiki for the new Median U-Turn Intersection

https://www.waze.com/editor/?lon=-86.06 ... 01&env=usa

MUTI's where the turn around segments have cross traffic from the left & right.

Re: [New Page] Median U-turn intersection

Fri Mar 21, 2014 3:55 pm

MeridianHills wrote:One thing that could be added into the wiki for the new Median U-Turn Intersection
https://www.waze.com/editor/?lon=-86.06 ... 01&env=usa
MUTI's where the turn around segments have cross traffic from the left & right.

That may not be a bad idea, particular since there are a number of odd situations that may arise where the Michigan Left instruction does not apply to all traffic crossing the physical segment. In that case, there is sometimes a need for a "logical" separate segment.

Here's a fairly common one where the median crossover serves as the entrance for an intersecting street, where it was important to preserve the turn instruction with the proper street name, and I've come across two or three other things similar to it.

To eliminate as much confusion as possible, perhaps we could have a small "guide" with a table and sample pics for different configurations, similar to what is done for the Road Type Guide on the roundabout page.

Re: [New Page] Median U-turn intersection

Fri Mar 21, 2014 4:08 pm

The guide is a great idea.

One thing I wasn't thinking about when I helped create that one in Indianapolis is that the segments can share one node, just not both. Of course it makes more sense to share the entrance node, since that makes applying turn restrictions easier. That should be the recommended practice in such situations (such as the Michigan example posted just above).

Re: [New Page] Median U-turn intersection

Fri Mar 21, 2014 4:19 pm

davielde wrote:
MeridianHills wrote:One thing that could be added into the wiki for the new Median U-Turn Intersection
https://www.waze.com/editor/?lon=-86.06 ... 01&env=usa
MUTI's where the turn around segments have cross traffic from the left & right.

That may not be a bad idea, particular since there are a number of odd situations that may arise where the Michigan Left instruction does not apply to all traffic crossing the physical segment. In that case, there is sometimes a need for a "logical" separate segment.

Here's a fairly common one where the median crossover serves as the entrance for an intersecting street, where it was important to preserve the turn instruction with the proper street name, and I've come across two or three other things similar to it.

To eliminate as much confusion as possible, perhaps we could have a small "guide" with a table and sample pics for different configurations, similar to what is done for the Road Type Guide on the roundabout page.


I think I would get confused if I was taking that drive, no matter which one of the three streets I was headed for, but maybe that's just me, from a fairly J-turn-free part of the world.

Re: [New Page] Median U-turn intersection

Fri Mar 21, 2014 4:31 pm

Heh, well you can trust it'd be a lot more confusing if you were navigating and single segments were used. "Turn left on Jackson Rd E / to Wagner Rd S" to go to Jackson Plz is misleading, and leaving it unnamed makes it inconsistent with the rest of the state.

Re: [New Page] Median U-turn intersection

Fri Mar 21, 2014 5:01 pm

But having it named seems inconsistent with general ramp rules. The naming seems there to maintain the illusion of left turn at the previous intersection, but I don't know how much good it does. Especially since it might sometimes result in an announcement about the cross street (your real target) as you approach that cross street. That might seem like you are being asked to make an illegal turn.

Changing the hundreds or thousands of these examples may not be practical, but I would have left them all unnamed to begin with. I'd still consider leaving this example unnamed, because even though it is inconsistent with all those other J's, the vast majority of those other J's don't have the complications of this one. Trying to meet the convention is forcing you into this weird dual segment, which is introducing ugliness to save purity.

Re: [New Page] Median U-turn intersection

Fri Mar 21, 2014 6:50 pm

qwaletee wrote:But having it named seems inconsistent with general ramp rules. The naming seems there to maintain the illusion of left turn at the previous intersection, but I don't know how much good it does. Especially since it might sometimes result in an announcement about the cross street (your real target) as you approach that cross street. That might seem like you are being asked to make an illegal turn.

I'm not sure what you mean by "inconsistent with general ramp rules". The names mostly follow Waze standards for ramp naming — they match local signage. The only difference is the second "to", which is consistent with the standards apparently set forth in the MUTCD — like on any exit sign that says "TO", the part after that is not the immediate destination of that ramp but follows soon thereafter.

Announcing the "real target" cross street is kind of the point. Consider Metro Pkwy at Mound. Say you're traveling northbound on Mound and need to go westbound on Metro Pkwy. Unnamed, your next turn instruction would be "[Left Turn] Mound Rd", which doesn't tell you much at all, you're already on Mound. Named as here, though, you'd get "[Left Turn] to Mound Rd S / to Metro Pkwy W". The first part, for Mound Rd S, is the immediate result of taking that "ramp" segment; the next part tells you where you might be headed next. But it's not sufficient to simply put "to Metro Pkwy W", because (1) that would imply that your immediate destination is Metro Pkwy W, and (2) although MDOT and Macomb County recommend that you turn right then turn around, Waze will choose whichever is faster.

Also, the signs say it like that, in that order. MDOT signs Michigan lefts on state and US highways as such, and Macomb County certainly follows suit — I'd think it's fair to assume others do as well. Matching signs is how ramps are named.

Any potential confusion that might be incurred by the presence of the destination road's name is mitigated by (1) the first road's name, (2) the use of directionals, and (3) "to".

What would be confusing is if one part of one such intersection was missing that instruction. What would also be confusing is if you needed to make a left onto a street served directly by that segment. Using one or the other would disadvantage users in one situation or the other.

Simplicity in the map is an admirable goal, but not at the expense of correct and helpful directions.

Re: [New Page] Median U-turn intersection

Fri Mar 21, 2014 7:37 pm

qwaletee wrote:The naming seems there to maintain the illusion of left turn at the previous intersection, but I don't know how much good it does. Especially since it might sometimes result in an announcement about the cross street (your real target) as you approach that cross street. That might seem like you are being asked to make an illegal turn.

The navigational guidance cleanly matches whatever you will be routed onto. If Waze is going to route you onto the illusory "left" (left-left-right) turn for the main intersecting street that you've already passed, you'll see and hear that "ramp" instruction every time. If Waze intends to route you onto the street that intersects at the u-turn crossover itself, you'll just see and hear "turn left at [street]". The segment data may be polluted if you happen to "snap" to the wrong segment. Even in that case though, the dual segments are so close that there is not enough distance where a recalculation resulting in a bad instruction would occur. I haven't seen a "restricted turn not allowed" MP from that setup either, which may potentially occur if Waze has you on the wrong segment thinking that the continuation is the only allowed turn, when in fact you turn left.

Because of the added risk of crossing all of the lanes to get to the street, the vast majority of these Michigan Left turnovers do not line up with another street, so the full turnaround is the only option. IMO it is more of a bonus to the drivers trying to get to the other street or parking lot when they do line up (unless they get hit trying to cross a few lanes of traffic...). Along major roads, more and more of these setups where drivers have the two options are being controlled by traffic lights, by the way.

qwaletee wrote:Trying to meet the convention is forcing you into this weird dual segment, which is introducing ugliness to save purity.

It may be ugly from an editor standpoint, but the segments are so close together on the app even at the most detailed zoom level that they are indistinguishable with all themes except the Map Editor. In that case, there is only a small sliver of white under the green. I think that the benefit of the dual segment in reducing confusion for either outcome outweighs any ugliness.

Re: [New Page] Median U-turn intersection

Fri Mar 21, 2014 9:16 pm

There are no signs there that I can see, so you're not "following the BGS," which is how we usually name ramps. We make exceptions where there are multiple splits or crosses in short succession, and the readouts could become confusing. Here you are using an "implied" secondary name of "to Wilson."


I don't see how MUTCD plays into this at all. Are you saying you are following the naming that SHOULD be there per MUTCD but is currently missing from the road?

The chief issue you raise with an unnamed segment here is that it would say "left to SAME ROAD YOU ARE ON," though that could be mitigated by naming the split roadway with E and W qualifiers. Alternatively, the segment could be named U-turn, or a combined segment could be U-turn / Jackson Plz.
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