[Page Update] Intersections / U-turns under 15m

[MGODLEW]

After a discussion with Driving79 there was some initial confusion regarding an UR that stated no U-turns were allowed. She originally resolved the initial issue but then the requester had a subsequent update request which I then made what I believed to be the appropriate changes. After discussing the issue with her, we found that technically either solution would have worked. However, my justification for the changes I made

Reason being for the bowtie, it shows an actual turn restriction for the No U-turn in the editor should any future editors come look at this intersection where they might see your solution with a segment with turns allowed while under 14 but does not know the 14m rule which would likely result in confusion. Plus, for PA, I try to keep everything as defined in the the wiki, which as per the wiki which does not directly mention the 15m rule, I believe a bow tie would be the solution here even though yours would work as well.

Essentially, we found that the intersections wiki does not directly link or tie in any information on the 15m rule. Can you please create/incorporate Routing_penalties#Road_configurations into Junction_Style_Guide/Intersections Wiki to eliminate potential confusion in the future.

[voludu2]

I might suggest replacing the section "bow tie" (https://wiki.waze.com/wiki/index.php?ti ... section=13 ) as follows:

===== Bow tie =====
{{Anchor|Bowtie}}
The "bow tie" intersection method allows the restriction of U turns without restricting the left turns that make up the U turn.

Use the bow tie intersection only where necessary, and only at 4-way split road intersections (between two split roads, or between a split road and an unsplit road).

: [[File:Jct_bowtie.png]]
By reducing the intersection to a single point, we gain control over U-turns.

Additionally, the center segment of the H may introduce complexity to the map. If the cross street changes names at the junction, care must be taken to make the center segment have no name assigned. This will cause the segment to inherit the appropriate name depending on the direction of travel. This center segment is then different from either side so future "select all segments" operations in the editor will not capture this segment which may complicate editing.

Finally, the Waze systems also have difficulty in capturing average speeds for short segments, especially when traffic does not travel across a majority of the segment which may happen in a wide intersection. The center of the H would be totally vertical in the example above, but turning traffic would be traveling in more of a 45 degree angle. Add in the inaccuracy of many consumer GPS chips and wide intersections and you may have traffic never actually driving over the segment for certain movements.

'''NOTE:''' Be aware of the geometry used in the bow tie. If the angles are too steep (45 degrees or greater) a driver traveling along one of the one-way segments may be told to "turn" or "stay" at the intersection instead of receiving no instruction.

===== When to avoid a Bow Tie =====

If the center of the physical "H" is long and/or allows traffic to stop and queue within the median of the divided roadway, a bow tie may not be appropriate. In these cases the segment may be long enough to justify being mapped especially if the one-way roads would have to deviate greatly from their physical location to meet in a single point.

[[File:MinSegLengthUturn2.png|border|390px|right|Segment too short to allow two left turns]] Waze will penalize a route with two left turns in less than {{:Routing penalties/U-turn minimum}} in [[right-hand traffic]] jurisdictions or with two right turns in less than {{:Routing penalties/U-turn minimum}} in [[left-hand traffic]] jurisdictions.
{{clear}}

{{ReturnJSG}}

[CBenson]

Again, if the junction box isn't a mirage permanently on the horizon, then I'm not worrying too much about bowties and odd internal bars on U-turns. All this should eventually become moot.

[voludu2]

So is it worth putting up something to say that these are currently two valid ways to draw such intersections, just so the new editors can come up to speed with the "NOW", and maybe mention that waze may introducing other alternatives in the future?

[CBenson]

Sure. I'm just noting why I'm not putting much time into to perfecting the explanation.

[voludu2]

Ok if I go ahead and implement the imperfect explanation?

[PesachZ]

Ok if I go ahead and implement the imperfect explanation?

Is be OK with it as well but I would separate it into two options with separate section headers under how to avoid U-turns in split roads, option a) ensure the median segment is <15 meters, AND the turn angles are exactly 90°, option b) bow tie. With your explanations.

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[PesachZ]

Ok if I go ahead and implement the imperfect explanation?

I made a few minor modifications to the H intersection section. Changed junction angle to turn angle, and fixed some typos. Today I replaced "the cross bar will be very short" with "the cross bar will be less than {{: segment length/minimum}}".

Two more changes I think should be made:

There should be a note at the top of the section that it also applies to box (#) intersections.

The reference added to " double lefts" needs to specify "in RHT countries, and double right in LHT countries".

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[voludu2]

A Box is just sort of 2 H's
Box junction is not defined on the wiki, that I can find, and might need an illustration eventually.
the heading is changed.

Basically, this is useful for u-turn prevention for cross-bars between minimum and u-turn minimum. So I'll think about rewording to make this simpler.

[PesachZ]

A Box is just sort of 2 H's
Box junction is not defined on the wiki, that I can find, and might need an illustration eventually.
the heading is changed.

Basically, this is useful for u-turn prevention for cross-bars between minimum and u-turn minimum. So I'll think about rewording to make this simpler.

It may not be defined in that term, but it is mentioned with pictures as a split / split intersection.

Perhaps the title could be "Split road junction"

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