Difference between revisions of "Routing penalties/Controlling U-turn penalties"

From Wazeopedia
({{@|Allowing median U-turns}}: consistent use of "conditions" instead of switching to "criteria", segments A,B,C, Use simpler words.)
({{@|Checking for parallel incoming and outgoing segments}}: slightly simpler words. Segment A, B, and C)
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==== {{@|Checking for parallel incoming and outgoing segments}} ====
 
==== {{@|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. These two segments are considered parallel if their angles with respect to a ''straight'' median segment sum to 180±5º (i.e, between 175º and 185º).  
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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.
  
Angles can be easily checked with the [[Scripts#WME_Junction_Angle_info|Junction Angle Info]] script add-on, which can be set to report absolute angles or [[How_Waze_determines_turn_/_keep_/_exit_maneuvers|turn angles]] ("departure"). For the purpose of determining parallelism, summing either measurements will work.
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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.
 
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[[File:U-turn_Parallel_Check_Straight.png||center]]
 
[[File:U-turn_Parallel_Check_Straight.png||center]]
  
 
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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
However, if the median segment has geometry nodes and is not straight, it cannot be used as a reference. In this case, temporarily add a straight segment to the same junctions as the existing curved median. Check the angles using this straight median and delete when done.
 
 
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[[File:U-turn_Parallel_Check_Curved.png]]
 
[[File:U-turn_Parallel_Check_Curved.png]]

Revision as of 12:16, 9 September 2015

Median U-turn penalty link to this section

For the latest discussion on this section please visit the wiki forum thread.
U-turn Roads.png

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 link to this section

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

  1. 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
  2. Segment B is shorter than 15 m (49.21 feet)
  3. 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 link to this section

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 link to this section

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.

U-turn Parallel Check Straight.png

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
U-turn Parallel Check Curved.png

Common mistakes link to this section