# Changes

## Routing penalties/Controlling U-turn penalties

, 6 months ago
Fixed JB rank error (was 5, now using Rank template) in "Allowing median U-turns" section
=== {{@|Median U-turn penalty}} ===
{{anchor|Avoiding U turns|Avoiding U turns in box and partial box intersections}}
==== {{@|Preventing median U-turns}} ====
# '''Three segments''': The U-turn is a reversal of driving direction through three segments: <br>an incoming segment&nbsp;(A), a single median segment&nbsp;(B) and an outgoing segment&nbsp;(C).
# '''Short median''': The median segment&nbsp;(B) is shorter than 15 meters (49.21 feet)equal to {{:Routing_penalties/U-turn_minimum|less}} or less.
# '''In/out parallelism''': The in and out segments (A&nbsp;and&nbsp;C) are [[#Checking for parallel incoming and outgoing segments|within ±5° of parallel]] to each other.
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{{Mbox|type=important|text=It is possible for this method to fail to prevent a U-turn when it is the first segment of a route , or it immediately follows a reroute. If you observe this method to fail in other situations when it is implemented properly, please report it in [http://www.waze.com/forum/viewtopic.php?p=994385#p994385 this forum thread]}}
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==== {{@|Allowing median U-turns}} ====
{{construction
| contact = https://www.waze.com/forum/viewtopic.php?f=1636&t=241061
| contacttype = forum
| draft = no
| open = no
| revision = yes
| section = yes
| talk = no
}}
To allow median U-turns in both directions, break condition #2 by making the median segment&nbsp;(B) {{:Routing_penalties/U-turn_minimum|greater}} ''or longer''
To allow a double-left or doubleU-right turn through from only one direction, first setup the median segmentintersection to allow U-turns in both directions. Then, break any one of the add a [[#Preventing median Junction Box]], and restrict the prohibited U-turnsturn route. A rank {{Rank|jb}} user or above conditions]]is required to install a Junction Box. For example: * To allow median {{mbox|text=Previously, unidirectional U-turns in both directions, break turn prohibition on a divided road was set up by breaking condition #2 by making 3 of the U-turn prevention mechanism through the median segment&nbsp;(B) 16 meters (52use of a [[Glossary#mDL|micro-dogleg]]. {{As of|2017}}, Waze staff has expressed a preference that map editors use Junction Boxes in these situations.5 feet) or ''longer''}}<!-- OLD INFORMATION * To allow a U-turn from only one direction, first set up U-turn prevention for both directions. Break condition #3 on the side where U-turns are allowed. Increase or decrease the angles so that the in and out segments (A and C) are [[#Checking for parallel incoming and outgoing segments|not parallel]]. A [[Glossary#mDL|micro-dogleg]] can be used to change the angle without changing the appearance of the segment.<br>[[File:U-turn selective Uturn prevention.png|center]]-->
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==== {{@|Checking for parallel incoming and outgoing segments}} ====
Condition #3 for U-turn prevention requires that the in and out segments (A&nbsp;and&nbsp;C) are within ±5º of parallel to each other. This is checked by using a ''straight'' median segment as the reference and the [[Scripts#WME_Junction_Angle_info|Junction Angle Info]] (JAI) browser extension to measure angles. JAI may be set for absolute or [[How_Waze_determines_turn_/_keep_/_exit_maneuversInteractive_junction_instruction_algorithm#Turn_angle|turn angles]]; using either is OK.
===== {{@|Straight median segments}} =====
If the median segment&nbsp;(B) is straight, add sum the two angles making up the U-turn::# The angle between the in-segment&nbsp;incoming and median segments (between A) and median&nbsp;(B) and the :# The angle between the median&nbsp;and outgoing segments (between B) and out-segment&nbsp;(C). The in and out segments (A&nbsp;and&nbsp;C) are considered parallel if the sum of these angles is {{font color|red|between 175º and 185º}}, .
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{| style="border: 0px; text-align: center; line-height: 1; font-size: small;"|-| [[File:U-turn_Parallel_Check_Straight.png||680px]]|- | style="padding-bottom: 20px;" | The short 14m median segment in the above examples satisfies condition #2 for U-turn prevention.|}
===== {{@|Curved median segments}} =====
If the median segment&nbsp;(B) has been shaped with geometry nodes, it is not straight and cannot be used for determining parallelism. Instead, draw a straight segment connected at the same in and out junctions (where in-segment&nbsp;(A) junctions with the mediansegment&nbsp;(B) and where the mediansegment&nbsp;(B) junctions with the out-segment&nbsp;(C)). Check the angles using this new straight segment , and delete the new segment afterwards.  ''Note: Be sure the junctions are unlocked, otherwise connecting a temporary segment to locked junctions will produce a save error even if it is deleted prior to saving.''
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[[File:U-turn_Parallel_Check_Curved.png||680px]]
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{{mbox|type=protection|text=Be sure the [[Editing_permissions#Locked_junction|junctions are not locked]] above your rank. Otherwise, drawing a new temporary segment connected to locked junctions may produce a save error even if it is deleted prior to saving.
{{Expand|
# Disable the [[Map_Editor_Interface_and_Controls#Settings_Tab|WME setting]] "Draw new roads with all turns allowed" before drawing the new segment.
# Draw the new segment disconnected from any other segment, then drag the end nodes to connect to the junctions.
|workaround options when any segments connected to either junction node cannot be edited.
|nt=yes}}}}

| [[File:U-turn_example_2mediansegs-bdp.png|243px]]
| Cutting a median segment into two may have unintended consequences
| U-turns are legal at this intersection. Even though U-turn prevention will ''not'' be triggered here, Waze will rarely route a U-turn at this intersection. When the railroad was junctioned with the median segment, it cut a single median into two. The two-segment discontinuity between divided roads of Major Blvd will can trigger a lower penalty mechanism designed to discourage detours off the main road (see [[Detour_Prevention_Mechanisms/USA#Big_Detours|Big Detour Prevention]], BDP).
|- style="background-color: #fff;"
| [[File:U-turn_example_2mediansegs-allowed.png|243px]]
| Cutting a median segment into two may have unintended consequences
| U-turns are not legal at this intersection, but Waze may route a U-turn here anyway. Cutting the median breaks condition #1, so U-turn prevention will not trigger. Unlike the railroad exampleFurthermore, BDP will might not trigger here either since the divided east and westbound roads do if all of its criteria are not have matching primary nor alternate namesmet.
|- style="background-color: #fff;"
| [[File:U-turn_example_curvedU.png|243px]]
| A median segment {{:Routing penalties/U-turn minimum|greater}} or longer than 15&nbsp;m (49.21&nbsp;ft) will always allow a U-turn| While condition #3 requires a straight segment for determining parallel in and out segments, condition #2 is the measure of the length of the median segment itself. Be careful when the space between the divided roads road is small. Ensure the U-turn segment is {{:Routing penalties/U-turn minimum|greater}} or longer than 15&nbsp;m (49.21&nbsp;ft) by adjusting its geometry. Conversely, a A median segment of any shape can trigger a U-turn penalty between parallel roads if it is not long enough.
|- style="background-color: #fff;"
| [[File:U-turn_example_parkinglot.png|243px]]
| To ensure proper routing between two closely spaced parallel roads, connect the two with a segment 16&nbsp;m (52.5&nbsp;ft) {{:Routing penalties/U-turn minimum|greater}} or longer
| U-turn prevention triggers for both double-left and double-right turns over any road type. If the three conditions for median U-turn prevention are met, a large penalty will be applied, irrespective of whether the turn is onto the same road in the opposite direction or onto a completely different road. Both double-left and double-right turns can be penalized, regardless of country, and can occur for one way or two way segments.
|}
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