[Tagging] Lanes tag, way forward

[Nathan Edgars II]

How does this sound for a compromise?

Many ways are not tagged with the total number of lanes at all points, 
but only with the number of through lanes. Therefore, end users should 
treat the lanes tag as a minimum rather than an exact number. Subtags 
(lanes:straight, lanes:right, etc.) or [[Relations/Proposed/turn 
lanes|turn lane relations]] can be used to provide more detail as well 
as an assurance that all lanes are mapped.

Unresolved issues:
*Should someone tagging all lanes also tag at least lanes:straight 
(especially if changing from through lanes to all lanes)?
*If a through lane becomes a turn lane, where is the exact location of 
the change? Where the first sign or pavement marking appears? (This can 
be a significant distance before the intersection, e.g. 'right lane must 
turn right 1/2 mi' or an overhead 'exit only'.) Where the dividing line 
changes from dashed to solid (if it does)? A set distance from the 
intersection (at least if none of these hold)?
*How should two-way lanes (center turn or reversible) be treated?