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(→‎Turn lanes: combined into single list)
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==Turn lanes==
==Turn lanes==
The majority of junctions do '''not''' need turn lanes at all. Waze gives advanced warning of upcoming turns, it is up to the user to pick the relevant lane for the approaching turn. Turn lanes should '''only''' be considered if there is a clear issue ''usually'' raised via MPs or URs. A lot of turn lanes are present on the map from the original basemap import and '''can be removed'''.
The majority of junctions do '''not''' need turn lanes at all. Waze gives advanced warning of upcoming turns, it is up to the user to pick the relevant lane for the approaching turn. Turn lanes should '''only''' be considered if there is a clear issue ''usually'' raised via MPs or URs.


===Do not to map turn lanes when...===
===Do not to map turn lanes...===
* the turn lane is '''too short''' (less than 200 ft or 60 m)  
* if the turn lane is '''too short''' (less than 200 ft or 60 m)  
* the turn lane is '''not distinct''', only separated by a single painted line, from the main direction of travel
* when the turn lane is '''not distinct''', only separated by a single painted line, from the main direction of travel
* the turn lane splits '''at or near''' the main junction stop or give way line.
* if the turn lane splits '''at or near''' the main junction stop or give way line.
* when the turn lane follows the obtuse angle of the junction
* unless better control is needed if a junction is too wide to trigger the [[global:Routing_penalties/Controlling_U-turn_penalties|u-turn prevention]] mechanism
* unless a complex junctions would ''benefit'' from additional instructions.


{| align="center"
{| align="center"
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|[[File:Uk-no-turn-lanes-3.png|200px|thumbnail|Splits at or near stop line]]
|[[File:Uk-no-turn-lanes-3.png|200px|thumbnail|Splits at or near stop line]]
|}
|}
===Turn lanes ''may'' be '''of benefit'''===
*Only when the turn lane splits from the main carriageway with a '''clear separation''', physical barrier or chevron markings
*Only if an acute angle ''may'' lead the user to misunderstand the location of the turn
<!--*Only if mapping some but not all turn lanes at a junction ''unbalances'' that junction-->
*Only for better control of u-turns when a junction is too wide to trigger the [[global:Routing_penalties/Controlling_U-turn_penalties|u-turn prevention]] mechanism
*Only for complex junctions that ''benefit'' from additional instructions.
{| align="center"
{| align="center"
|[[File:Uk-turn-lane-5.png|200px|thumbnail|Clear separation of turn lane]]
|[[File:Uk-turn-lane-5.png|200px|thumbnail|Clear separation of turn lane]]
|[[File:Uk-turn-lane-4.png|200px|thumbnail|Acute angle of junction]]
|[[File:Uk-turn-lane-4.png|200px|thumbnail|Acute angle of junction]]
<!--|[[File:example.png|200px|thumbnail|Balanced junction]]-->
|[[File:Uk-complex-junction.png|200px|thumbnail|Complex junction]]
|[[File:Uk-complex-junction.png|200px|thumbnail|Complex junction]]
|}
|}

Revision as of 15:38, 1 December 2017

Turn lanes

The majority of junctions do not need turn lanes at all. Waze gives advanced warning of upcoming turns, it is up to the user to pick the relevant lane for the approaching turn. Turn lanes should only be considered if there is a clear issue usually raised via MPs or URs.

Do not to map turn lanes...

  • if the turn lane is too short (less than 200 ft or 60 m)
  • when the turn lane is not distinct, only separated by a single painted line, from the main direction of travel
  • if the turn lane splits at or near the main junction stop or give way line.
  • when the turn lane follows the obtuse angle of the junction
  • unless better control is needed if a junction is too wide to trigger the u-turn prevention mechanism
  • unless a complex junctions would benefit from additional instructions.
Turn lane too short
Turn lane not distinct
Splits at or near stop line
Clear separation of turn lane
Acute angle of junction
Complex junction

If turn lanes really are of benefit to the driver, then they should be mapped in the following way:

  • Do not map the turn lane longer than it is in reality, Waze already has mechanisms for dealing with queuing traffic
  • Turn lanes must never cross a side road before a junction, they must start between the side road and main junction to give clear instructions
  • The turn lane segments should have no name, so that the instructions read out the name of the next street
  • The Road Type should match the type of the roads they lead to (and never ramps). Only the main carriageway stays as the higher Road Type
  • The angle at the beginning of the turn lane should be shallow, so that Waze says Keep Left / Right at that point
  • The end of the turn lane should have a clear turn instruction near to the give-way point, unless the traffic merges onto the new road with right-of-way.