[Tagging] lanes = 0

Philip Barnes phil at trigpoint.me.uk
Thu Jun 13 16:33:49 UTC 2019

On Thu, 2019-06-13 at 12:46 +0100, ael via Tagging wrote:
> On Thu, Jun 13, 2019 at 08:09:26PM +1000, Warin wrote:
> > On 13/06/19 18:41, Tobias Zwick wrote:
> > 
> > I think a tag to say "lane:marking=no" could be better for that
> > situation???
> > 
> > lanes=* says the number of lanes, it does not say if they are
> > marked or unmarked as demonstrated above.
> +1
> It had never occured to me that the lanes tag required markings: I
> had
> understood it to be mainly an aid for routing, algorithmic or manual.
> If it requires marking, then most of my own maping of lanes would
> need
> revision. And since I have no good way of estimating widths, I
> wouldn't
> know how to preserve the information with alternative tagging.
In the UK a two way road of less than 4.5m will (usually) have no lane
markings. Locally you can assume that almost any rural road below
secondary will be too narrow to have lanes and there are a few
secondary roads that meet that criteria. And obviously bridges tend to
be narrower.

I tend to map these roads using the width tag.

Commonly a 4m road you can pass other cars comfortably, but have to
slow to pass larger vehicles, 3.5m then you are starting to think about
the timing to be at wider bits to pass oncoming traffic.

Where there are no lanes then the width tag allows routers to make an
informed choice, 4m is reasonable for a a car but not a good idea in a
truck unless it is to reach its destination. 

I am not sure if routers use this tag?

Phil (trigpoint)

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