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Routing penalties/Controlling U-turn penalties

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=== {{@|Controlling Median U-turnsturn penalty}} ===
{{anchor|Avoiding U turns|Avoiding U turns in box and partial box intersections}}
{{hatnote|This article discusses double turn U-turns, for a standard one or two segment U-turn adjust the [[Interface_guide#Junction_Arrows|junction arrows]].}}{{Mbox|type=forum|style = background: #cadceb;|text=For the latest discussion on this section please visit the wiki forum thread [ <nowiki>[Page Update] Intersections / U-turns under 15m</nowiki>the wiki forum thread].}} 
The Waze routing algorithm sets a [[Routing penalties#Road_configurations|penalty]] for some double-left or double-right turns. This can prevent U-turns at H or # -style intersections on divided and parallel roads. This means that, even if both of the turns that make up the U-turn are allowed, the combination of the two turns might be prevented. If one of the two turns making up the U-turn is restricted or impossible, disallow that turn. The U-turn will then not be routed, and the following penalty does not matter. 
==== {{@|Preventing median U-turns}} ====
An extremely A large U-turn penalty is set for a double-left or double-right turn when '''''all three''''' of the conditions below are met:
# '''Three segments''': The U-turn is involves a reversal of driving direction through three 3 segments: <br>A) an incoming segment&nbsp;(A, B), a single median segment&nbsp;(B, and C) and an outgoing segment&nbsp;(C).# '''Short median''': The median segment&nbsp;(Segment B) is shorter than {{:Routing_penalties/U-turn_minimum}}.<br>''As a safety margin, leave a 1 15 m buffer zone by using {{:Routing_penalties/U-turn_minimum|less}} or less(49.''21 feet)# '''In/out parallelism''': The in and out segments (Segment A&nbsp;and&nbsp;C) segment B are [[#Checking for parallel incoming and outgoing segments|within ±5° of parallel]] to each other.
{{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 reroute. If you observe this method to fail when it is implemented properly, please report it in [ this forum thread]}}
==== {{@|Allowing median U-turns}} ====
To allow a double-left or double-right turn through the a median segment, break any one of the [[#Preventing median U-turns|above conditions]]. For example:
* To allow median U-turns in both directions, break condition #2 by making the the median segment&nbsp;B longer than 15 m (B49.21 ft) {{:Routing_penalties/U-turn_minimum|greater}} ''or longer''* 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 Then, to allow U-turns are allowed. Increase or decrease on one side, change the angles so that the in and out segments (for segment A and C) segment B so they 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 segment. [[File:U-turn selective Uturn prevention.png|center]]
==== {{@|Checking for parallel incoming and outgoing segments}} ====
Condition #3 for U-turn prevention requires that the in incoming and out outgoing segments (A&nbsp;and&nbsp;C) are to be 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 the angles. JAI may be set for absolute or [[Interactive_junction_instruction_algorithm#Turn_angleHow_Waze_determines_turn_/_keep_/_exit_maneuvers|turn angles]]; using either setting is OK.
===== {{@|Straight median segments}} =====If the median segment B is straight, sum measure the two angles making up the U-turn::# The angle between the incoming and median segments (between segment A and segment B):# The angle between the median , and outgoing segments (between segment B and segment C)The in and out segments (A&nbsp;and&nbsp;C) are considered parallel if . If the sum of these angles is {{font color|red|between 175º and 185º}}, segment A and segment B are considered parallel.
{| style="border: 0px;text-align: center; line-height: 1; font-size: small;"|-| [[File:U-turn_Parallel_Check_Straight.png|680px|center]]|- | style="padding-bottom: 20px;" | The 14m median segment in the examples above 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 . It cannot be used for determining parallelismto measure the turn angles. Instead, draw a straight segment connected at to the same in and out junctions (where in-used by segment&nbsp;(A) junctions with the median segment&nbsp;(B) and where the median segment&nbsp;(B) junctions with the out-segment&nbsp;(C)). Check the angles using this new straight segment, and delete median. Delete the new segment straight median afterwards.
{{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.
# 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 segment(s) connected to either junction node are locked above your rank.
<includeonly>Please see the [[Routing penalties/Controlling U-turns#Additional examples|Controlling U-turns]] article for more advanced details, and additional examples.</includeonly><noinclude>
==== {{@|Additional examplesCommon mistakes}} ====<div style="font-size:smaller">{| class="wikitable" cellpadding=2 style="width: 100%; text-align: left;" ! style="width: 247px" | Example! style="width: 120px" | Tip! Details|- style="background-color: #fff;"| [[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 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. Furthermore, BDP might not trigger here if all of its criteria are not met.|- style="background-color: #fff;"| [[File:U-turn_example_curvedU.png|243px]]| A median segment longer than {{:Routing penalties/U-turn minimum}} 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 road is small. Ensure the U-turn segment is longer than {{:Routing penalties/U-turn minimum}} by adjusting geometry. 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 {{: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.|}</div></noinclude>