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{{anchor|Avoiding U turns|Avoiding U turns in box and partial box intersections}} | {{anchor|Avoiding U turns|Avoiding U turns in box and partial box intersections}} | ||
{{hatnote|This article discusses double-turn U-turns. For standard one or two segment U-turns, adjust the [[Interface_guide#Junction_Arrows|junction arrows]].}} | {{hatnote|This article discusses double-turn U-turns. For standard one or two segment U-turns, adjust the [[Interface_guide#Junction_Arrows|junction arrows]].}} | ||
{{ | <br /> | ||
{{:Editing Routing penalties/Controlling U-turn penalties/Disabled}} | |||
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{| style="float: right; width: 360px; border: 0px;text-align: center; line-height: 1; font-size: small;" | {| style="float: right; width: 360px; border: 0px;text-align: center; line-height: 1; font-size: small;" | ||
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| style="padding-bottom: 20px; padding-left:10px;" |''Note:'' The road types displayed in the images might not match the standards for where you edit. Please check your local wiki and with local experts to learn the correct road type to use for '''median segments''' in your area. | | style="padding-bottom: 20px; padding-left:10px;" |''Note:'' The road types displayed in the images might not match the standards for where you edit. Please check your local wiki and with local experts to learn the correct road type to use for '''median segments''' in your area. | ||
|} | |} | ||
It | === Historic U-turn routing prevention === | ||
The Waze routing algorithm previously had a method of penalizing some double-left and double-right turns. This used to prevent U-turns at H or # style intersections on divided and parallel roads. Expand the section below to learn how this used to work. {{Collapsible section top}} | |||
{{Collapsible section content}} | |||
It was useful for preventing the sequence of two turns that would make up the U-turn, while still allowing the individual turns. However, if either of the two turns making up the U-turn was illegal or impossible, it would disallow that turn instead. The U-turn would then not be routed, and the following penalty would not matter. | |||
==== {{@|Preventing median U-turns}} ==== | ==== {{@|Preventing median U-turns}} ==== | ||
An extremely large U-turn penalty | An extremely large U-turn penalty was set for a double-left or double-right turn when '''''all three''''' of the conditions below were met: | ||
# '''Three segments''': The U-turn is a reversal of driving direction through three segments: <br>an incoming segment (A), a single median segment (B) and an outgoing segment (C). | # '''Three segments''': The U-turn is a reversal of driving direction through three segments: <br>an incoming segment (A), a single median segment (B) and an outgoing segment (C). | ||
# '''Short median''': The median segment (B) is | # '''Short median''': The median segment (B) is equal to {{:Routing_penalties/U-turn_minimum|less}} or less. | ||
# '''In/out parallelism''': The in and out segments (A and C) are [[#Checking for parallel incoming and outgoing segments|within ±5° of parallel]] to each other. | # '''In/out parallelism''': The in and out segments (A and C) are [[#Checking for parallel incoming and outgoing segments|within ±5° of parallel]] to each other. | ||
<br> | <br> | ||
{{Mbox|type=important|text=It | {{Mbox|type=important|text=It was possible for this method to fail to prevent a U-turn when it was the first segment of a route, or it immediately followed a reroute. Previously, if you observed this method to fail in other situations when it is implemented properly, you would report it in [http://www.waze.com/forum/viewtopic.php?p=994385#p994385 this forum thread].}} | ||
<br> | <br> | ||
Previously, to allow median U-turns in both directions, you would break condition #2 by making the median segment (B) {{:Routing_penalties/U-turn_minimum|greater}} ''or longer.'' | |||
Previously, to allow a U-turn from only one direction, you would first setup the intersection to allow U-turns in both directions. Then, add a [[Junction Box]], and restrict the prohibited U-turn route. A rank {{Rank|jb}} user or above is required to install a Junction Box. | |||
{{mbox|text=Previously, unidirectional U-turn prohibition on a divided road was set up by breaking condition #3 of the U-turn prevention mechanism through the use of a [[Glossary#mDL|micro-dogleg]]. {{As of|2017}}, Waze staff has expressed a preference that map editors use Junction Boxes in these situations.}} | |||
<!-- 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. | |||
* 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. | [[File:U-turn selective Uturn prevention.png|center]]--> | ||
[[File:U-turn selective Uturn prevention.png|center]] | |||
<br> | <br> | ||
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| [[File:U-turn_example_2mediansegs-bdp.png|243px]] | | [[File:U-turn_example_2mediansegs-bdp.png|243px]] | ||
| Cutting a median segment into two may have unintended consequences | | 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 | | 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#Big_Detours|Big Detour Prevention]], BDP). | ||
|- style="background-color: #fff;" | |- style="background-color: #fff;" | ||
| [[File:U-turn_example_2mediansegs-allowed.png|243px]] | | [[File:U-turn_example_2mediansegs-allowed.png|243px]] | ||
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| 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. | | 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. | ||
|} | |} | ||
{{Collapsible section bottom}} | |||
</div> | </div> | ||
</noinclude> | </noinclude> |
Latest revision as of 06:24, 22 August 2022
This article discusses double-turn U-turns. For standard one or two segment U-turns, adjust the junction arrows.
As of December 2021[update], the Waze routing algorithm penalizing some double-left and double-right turns has been disabled in the United States. The routing server will no longer automatically avoid double-left turns. To prevent u-turns on divided roads, use a Junction box. |
Historic U-turn routing prevention
The Waze routing algorithm previously had a method of penalizing some double-left and double-right turns. This used to prevent U-turns at H or # style intersections on divided and parallel roads. Expand the section below to learn how this used to work.