[Tagging] Counting lanes: include merging or turn lanes?

Alan Millar am12 at bolis.com
Sun Jul 4 21:41:16 BST 2010


How are people using the "lanes" tag on motorways?  Do you count the  
on/off ramps that come and go?

On a lot of the freeways near me, they have two main driving lanes on  
each direction, so I set it up as a dual carriage way with one-way on  
each side, and mark each side as lanes=2.

The question comes in for the on/off ramps.  There are sections where  
two intersections are somewhat close together, and so there is an on- 
ramp, a long extended merging lane, then the next off ramp.    
Strictly speaking, there is a third lane for some distance between  
the the ramps, but it isn't a "through" lane.  There are only 2  
driving or through lanes in that section of freeway.

See for example hwy 217 between Denney and Allen at:

http://www.openstreetmap.org/? 
lat=45.473345&lon=-122.786743&zoom=18&layers=B000FTT

I have only been counting the driving or through lanes, so I have  
tagged this as lanes=2, and just ignored the short extent of the  
extra merging lane.

Likewise, there are suburban streets that have an extra turn lane  
just before an intersection, like Murray Blvd at:

http://www.openstreetmap.org/? 
lat=45.4814&lon=-122.8261&zoom=18&layers=B000FTTT

As one big street with two driving lanes each direction, I've tagged  
it as lanes=4 and ignored the short extent of the extra turn lane.

And one more variation is the suburban boulevard with one center  
lane, only allowed to be used for turning/merging in and out of  
driveways.  I consider this like the freeway merging lanes; I've just  
been counting the driving lanes and not the turning lane also.  See  
Canyon Road at:

http://www.openstreetmap.org/? 
lat=45.489479&lon=-122.799664&zoom=18&layers=B000FTTT

So, is this what other people are doing?  Any pros/cons to handling  
to merging and turn lanes like this?

Thanks

- Alan





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