Add support for U-turns

[milkboy]

Parallell (±?°) roads with x (<15?) meters in between can cause a "make a U-turn" prompt

[FZ69617]

I don't get it. If distance between the two parallel (±5°) roads at the junction is less than 15m, then a U-turn is disallowed - see U-turn avoidance conditions in Wiki. In fact, I've never heard a "take a U-turn" instruction on the junctions with a U-turn allowed in between an entry and exit segments connected with a short segment - e.g. between this two segments two "turn left" instructions are emitted by Waze, instead of an effective "U-turn". AFAIK, the U-turn instructions are currently emitted only for a single, two-way roads at the junctions, or at ends of the roads (of course, only if allowed by a green U-turn arrow).

Nevertheless, I think it would be useful to show an angle between the two selected segments connected with another (short?) segment. And, in addition to the angle, tell the user whether a U-turn is allowed or not between these two selected segments - for example, it's not obvious for everyone that a U-turn is disallowed here. What do you think?

[wlodek76]

Interesting Idea! To show U-turn using JAI instead of thinking does it generates or not ;) Many editors even advanced still have troubles with it!

Some tricky example where U-turn works and it was forced. https://www.waze.com/pl/editor/?env=row&lon=19.55355&lat=51.75735&layers=388&zoom=10&segments=119190011

It could be nice to estimate U-turn in JAI. For example examine two selected segments and displaying U-Turn icon or a just simple marker with a word U-Turn could be enough.

Even for one selected segment it is possible to show this (we need to examine all following parallel segments) a little challenge but possible :)

[milkboy]

As long as people don't expect a "u-turn" guidance ;) Forcing this way makes the routing into two separate "turn lefts"

[FZ69617]

@milkboy could you please reopen this issue? I have almost finished support for this on my desk. :)