From Wazeopedia
{{@|Checking for parallel segments}}
* To selectively allow a U-turn from only one direction, first setup U-turn prevention as you would for both directions. Then, for the side where U-turns are allowed, make the incoming and outgoing segments sufficiently [[#Checking for parallel segments|non-parallel]]. (Tip: consider using a [[Glossary#mDL|Micro-dogleg]] to discreetly adjust the angle without affecting appearance)
==== {{@|Checking for parallel incoming and outgoing segments}} ====
A convenient way Condition #3 for U-turn prevention requires the incoming and outgoing segments to check if the be within ±5º of parallel to each other. These two side segments are considered parallel is if their angles with respect to use another segment as a reference tool. If the ''straight'' median segment has no geometry nodessum to 180±5º (i.e, it can be the reference segment. Otherwise you can draw a new segment as a reference tool with no geometry which connects the A between 175º and B nodes of the median segment185º). ''The reference segment can be deleted after the check is complete, if appropriate.''
Check two angles:# X — Angles can be easily checked with the angle between the incoming one-way segment and the reference segment[[Scripts# Y — the angle between the outgoing oneWME_Junction_Angle_info|Junction Node Info]] script add-way segment and on, which can be set to report absolute angles or [[How_Waze_determines_turn_/_keep_/_exit_maneuvers|turn angles]] ("departure"). For the reference segmentpurpose of determining parallelism, summing either measurements will work.
If the sum of these two angles is within 5° of 180° (between 175[[File:U-185°), then the roads are considered parallelturn_Parallel_Check_Straight.png||center]]<br>
In However, if the example below, angle X median segment has geometry nodes and is 102°not straight, and angle Y is 75°it cannot be used as a reference. The sum is 177°In this case, which is within 3° of 180°temporarily add a straight segment to the same junctions as the existing curved median. Therefore these roads are considered parallelCheck the angles using this straight median and delete when done. [[File:LilyPondUU-turnturn_Parallel_Check_Curved.jpegpng]]