[OSM-talk] tagging roads

[Blaž Lorger]

On Sunday 02 August 2009 11:57:12 John Smith wrote:
> --- On Sun, 2/8/09, Blaž Lorger <blaz.lorger at triera.net> wrote:
> > Unfortunately lanes only specifies number of lanes. In
> > general every road that
> > is not one way has at least 2 lanes, even if it is narrow,
> > say 3.5 meters.
>
> Even one way roads can have multiple lanes. Like dual carriage ways :)
>
> > Some good practices
> > on how to accurately estimate road width could also came
> > handy.
>
> I feel you could get road widths accurately enough based simply on the
> number of lanes and the type of highway.
>
> For example, a residential road with 2 lanes, one in each direction is
> usually about 6-7m wide.
>
> Motorways are usually the numbers of lanes times 3m + 3m each side of the
> road way to allow for break downs, or maybe you could even have lanes=*
> breakdown_lanes=* to make this more accurate, but in any case a 3 lane
> motorway will be about 15m wide (3 * 3 + 3 + 3).

Main point here is to identify narrow roads. This is where road width matters 
the most. It is obvious that narrow roads will have 2 lanes. Unfortunately, 
those lanes will be narrow (2m or less). So number of lanes will in no way 
indicate road width, especially for narrow roads.