Routing penalties/Controlling U-turn penalties: Difference between revisions View history

Revision as of 17:10, 30 September 2015

Median U-turn penalty

For the latest discussion on this section please visit the wiki forum thread.

The Waze routing algorithm sets a penalty for some double-left or double-right turns. This can prevent U-turns at H-style intersections on divided and parallel roads.

Preventing median U-turns

A large U-turn penalty is set for a double-left or double-right turn when all three of the conditions below are met:

The U-turn involves a reversal of driving direction through 3 segments:
A) an incoming segment, B) a single median segment, and C) an outgoing segment
Segment B is shorter than 15 m (49.21 feet)
Segment A and segment B are within ±5° of parallel to each other

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 a median segment, break any one of the above conditions. For example:

To allow median U-turns in both directions, break condition #2 by making the the median segment B longer than 15 m (49.21 ft)
To allow a U-turn from only one direction, first set up U-turn prevention for both directions. Then, to allow U-turns on one side, change the angles for segment A and segment B so they are not parallel. A micro-dogleg can be used to change the angle without changing the appearance of segment.

Checking for parallel incoming and outgoing segments

Condition #3 for U-turn prevention requires the incoming and outgoing segments to be within ±5º of parallel to each other. This is checked by using a straight median segment and the Junction Angle Info (JAI) browser extension to measure the angles. JAI may be set for absolute or turn angles; either setting is OK.

If segment B is straight, measure the angles between segment A and segment B, and between segment B segment C. If the sum of these angles is between 175º and 185º, segment A and segment B are considered parallel.

If segment B has geometry nodes it is not straight. It cannot be used to measure the turn angles. Instead, draw a straight segment to the same junctions used by segment B. Check the angles using this straight median. Delete the straight median afterwards

@@ Line 1: / Line 1: @@
-=== {{@|Controlling U-turns}} ===
+=== {{@|Median U-turn 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|text=For the latest discussion on this section please visit [http://www.waze.com/forum/viewtopic.php?t=108731 the wiki forum thread].}}
-{{Mbox|type=forum|style = background: #cadceb;|text=For the latest discussion on this section please visit the wiki forum thread [http://www.waze.com/forum/viewtopic.php?t=108731 <nowiki>[Page Update] Intersections / U-turns under 15m</nowiki>].}}
 [[File:U-turn_Roads.png||360px|right]]
-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.
+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-style intersections on divided and parallel roads.
-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 large U-turn penalty is set for a double-left or double-right turn when '''''all three''''' of the conditions below are met:
+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 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).
+# The U-turn involves a reversal of driving direction through 3 segments: <br>A) an incoming segment, B) a single median segment, and C) an outgoing segment
-# '''Short median''': The median segment&nbsp;(B) is shorter than {{:Routing_penalties/U-turn_minimum}}.<br>''As a safety margin, leave a 1 m buffer zone by using {{:Routing_penalties/U-turn_minimum|less}} or less.''
+# Segment B is shorter than 15 m (49.21 feet)
-# '''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.
+# Segment A and segment B are  [[#Checking for parallel segments|within ±5° of parallel]] to each other
 <br>
 {{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 [http://www.waze.com/forum/viewtopic.php?p=994385#p994385 this forum thread]}}
@@ Line 21: / Line 18: @@
 ==== {{@|Allowing median U-turns}} ====
-To allow a double-left or double-right turn through the median segment, break any one of the [[#Preventing median U-turns|above conditions]]. For example:
+To allow a double-left or double-right turn through 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 median segment&nbsp;(B) {{:Routing_penalties/U-turn_minimum|greater}} ''or longer''
+* To allow median U-turns in both directions, break condition #2 by making the the median segment B longer than 15 m (49.21 ft)
-* 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 segment.
+* To allow a U-turn from only one direction, first set up U-turn prevention for both directions. Then, to allow U-turns on one side, change the angles for segment A and segment B so they are [[#Checking for parallel 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]]
 <br>
 ==== {{@|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 [[Interactive_junction_instruction_algorithm#Turn_angle|turn angles]]; using either is OK.
+Condition #3 for U-turn prevention requires the incoming and outgoing segments to be within ±5º of parallel to each other. This is checked by using a ''straight'' median segment and the [[Scripts#WME_Junction_Angle_info|Junction Angle Info]] (JAI) browser extension to measure the angles. JAI may be set for absolute or [[How_Waze_determines_turn_/_keep_/_exit_maneuvers|turn angles]]; either setting is OK.
-===== {{@|Straight median segments}} =====
+If segment B is straight, measure the angles between segment A and segment B, and between segment B segment C. If the sum of these angles is between 175º and 185º, segment A and segment B are considered parallel.
-If the median segment is straight, sum the two angles making up the U-turn:
-:# The angle between the incoming and median segments (between A and B)
-:# The angle between the median and outgoing segments (between B and C)
-The in and out segments (A&nbsp;and&nbsp;C) are considered parallel if the sum is {{font color|red|between 175º and 185º}}.
 <br>
-{| style="border: 0px;text-align: center; line-height: 1; font-size: small;"
+[[File:U-turn_Parallel_Check_Straight.png||center]]
-|-
-| [[File:U-turn_Parallel_Check_Straight.png|680px]]
-|-
-| style="padding-bottom: 20px;" | The 14m median segment in the examples above satisfies condition #2 for U-turn prevention.
-|}
-===== {{@|Curved median segments}} =====
+If segment B has geometry nodes it is not straight. It cannot be used to measure the turn angles. Instead, draw a straight segment to the same junctions used by segment B. Check the angles using this straight median. Delete the straight median afterwards
-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 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 the new segment afterwards.
 <br>
-[[File:U-turn_Parallel_Check_Curved.png||680px]]
+[[File:U-turn_Parallel_Check_Curved.png]]
 <br>
-{{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 segment(s) connected to either junction node are locked above your rank.
-|nt=yes}}}}
-<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 examples}} ====
+==== {{@|Common 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>