[Tagging] Dispute prevention: meaning of lanes tag

Philip Barnes phil at trigpoint.me.uk
Fri Apr 27 11:01:37 BST 2012

Through observations I can see that there is a minimum width for lane marking in the UK. I am not sure what the value is, but have seen sections of road where lines end where the road narrows.
Will try to find an example.

I am not sure I would want to add a lanes tag where the width falls below this minimum, and would tend to prefer the width tag.

Whilst following cars, it has occurred to me that knowing their width would be a reasonable yardstick for estimating the width of a road.


On 27/04/2012 10:29 Andrew Errington wrote:

I'm quite happy with lanes=n where n is an integer.

I am very happy to assume that a one-way road without lanes=* has only one 

I am also happy to assume that a not-one-way road without lanes=* has two 
lanes (one in each direction).

I am extremely happy to see a width=* tag that I can use in conjunction with 
the lane count (even if the lane count is assumed). It tells me the width of 
each lane.

A lane count of 1.5 is very confusing. What does it mean? What is the width 
of each lane? Is it really 1.5? Should it be 1.55, or 1.4, or 1.6? It's 
more useful to tell me width of the road. Then, if there is one lane I can 
see maybe it's very wide, or if two lanes I can see maybe they are very 
narrow. It's okay to let me assume the number of lanes because the 
assumption is safe, and if it's really wrong then someone will tag it 
properly later.

In summary, I think simpler is better. A non-integer lane count is useless. 
Use the width tag.

Best wishes,



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