[OSM-newbies] Splitting streets into one ways--too much?

Paul Johnson baloo at ursamundi.org
Thu Dec 9 05:34:02 GMT 2010

On 12/08/2010 04:09 PM, Steve Bennett wrote:
> Hi,
>   IMHO, if there is no physical barrier, it's a bad idea to map the
> two lanes individually. Some reasons:
> 1) It renders badly. In every renderer. Spurious one-way arrows, the
> road comes out looking wider, you get the extra lines down the middle,
> ugly intersections...

I think one could be argued that one should not omit for the renderer.

> 2) Routers no longer know that you can u-turn anywhere.

Many jurisdictions (Oregon, for example) prohibit u-turns at controlled
intersections unless otherwise posted ("U-turn permitted" signs).
U-turns tend to be prohibited across medians anyway.

> 3) You're losing the piece of information that the two lanes are
> physically contiguous. There should be some kind of relation binding
> them together, but none has been defined, afaik.

It's been observed before that one can create a polygon like a river and
tag it "landuse=highway" for right-of-way spaces.

> 4) It's misleading to users - it looks like a divided road, when it's not.

If it has a median, it's a divided road, by definition.

> 5) Causes various inaccurate flow-on effects, like a turning circle
> being represented as a single way, rather than an "area".

highway=turning_circle should only be used on nodes, anyway.

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