[Page update] Controlling_U-turn_penalties

[nzahn1]

Implementing the guidance from staff, that unidirectional U-turns on divided highways should use JB to prevent prohibited u-turns not micro-doglegs to ‘break’ U-turn prevention mechanisms.

Allowing median U-turns current

[code]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 median U-turns in both directions, break condition #2 by making the median segment (B) {{: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 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]][/code]Allowing median U-turns proposed

[code]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 median U-turns in both directions, break condition #2 by making the median segment (B) {{:Routing_penalties/U-turn_minimum|greater}} ‘‘or longer’’
• To allow a U-turn from only one direction, first setup the intersection to allow U-turns in both directions. Then, add a [[Junction Box]], and restrict the prohibited U-turn route. {{As of|2017}}, a rank 5 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.}}[/code]

[herrchin]

Perhaps remove the opening line completely? Instead of providing general guidance to break one of the 3 conditions, the bullets now provide the preferred and explicit way to handle unidirectional and bidirectional situations.

@WoP

To allow a double-left or double-right turn through the median segment, break any one of the above conditions. For example:

[voludu21]

I would like to do two things to this page:

1. remove the warning box under “allowing median u-turns”. I think this section should now be considered up to date
2. Add a section before examples explaining why we avoid a median segment length that would round to 15m (the value of {{Routing_penalties/U-turn_minimum|criterion}} would be 15m)

====Technical details====
WME display rounds segment lengths to the nearest meter (meters setting) or nearest .01 foot (imperial setting). Because the routing server uses a value of {{Routing_penalties/U-turn_minimum|criterion}} in deciding whether a median segment is short enough to apply the u-turn penalty, and because rounding means a median segment with displayed length of {{Routing_penalties/U-turn_minimum|criterion}} could have a true length in the range {{Routing_penalties/U-turn_minimum|criterion}} +/- .5m, it is recommended to avoid a median displayed length of {{Routing_penalties/U-turn_minimum|exact}}. {{Routing_penalties/U-turn_minimum}} or more when the penalty is to be avoided; {{Routing_penalties/U-turn_minimum|less}} or less when the penalty is desired.