User:Atrophicshiner/sandbox

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 turn 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 (less than 45 degrees), so that Waze instructs Keep Left / Right at the split point
• The end of the turn lane should have a clear turn instruction if there is a stop line (traffic lights) or if the angle of the turn is less than 135 degrees. If the traffic merges onto the new road with right-of-way no secondary instruction is needed.