[Talk-GB] traffic island mapping / harmful detail?

Sun Apr 4 08:09:10 UTC 2021

Hi Tom,

Thanks for your reply. My concern here was really that a posting about a user’s changeset ended up changing the wiki. I did not feel the need to get involved in discussing the changeset, but certainly would have got involved if the discussion had been for a proposal to update the wiki. There may well be others who would want to get involved if they thought the wiki was being changed. I was also concerned by “I think Tom's come round to the right conclusions here…” which was posted in the thread. In my view, what the writer means is “Tom has come round to my conclusion”, not necessarily the right one.

The title of the thread was about traffic islands but seemed to suddenly start discussing whether landuse should be coincident with a highway. DaveF is normally the voice of reason on here, but I just thought the point about landuse not being attached to highways was rather contentious as from what I can see there are a lot of people who disagree with this statement.

I hope I haven’t offended either of you.

Cheers,
Mike

From: Tom Crocker [mailto:tomcrockermail at gmail.com] 
Sent: 04 April 2021 08:08
To: Mike Baggaley <mike at tvage.co.uk>
Cc: Dave F via Talk-GB <talk-gb at openstreetmap.org>
Subject: Re: [Talk-GB] traffic island mapping / harmful detail?

Hi Mike.

Sorry if I'm the other member you think has been railroading their views. I was trying to present what I'd understood and hoped more experienced members would chip in. Thanks for doing so! I think that in updating the wiki Nick was probably acting in the absence of dissenting opinion (to that point).

Regards

Tom

On Sun, 4 Apr 2021, 00:34 Mike Baggaley via Talk-GB, <talk-gb at openstreetmap.org <mailto:talk-gb at openstreetmap.org> > wrote:
I am extremely unhappy with the way a couple of members have railroaded their views and propagated these into updates on the "Land use and areas of natural land" and " How to map landuse" pages under " GB discussion on the mapping of Land Use & Land Cover" as if there has been a detailed discussion and an agreement reached. I certainly have not agreed with these views.

The comments below have been presented as if they are facts, but they seem to me to be personal views.

>1. Any stationary, physical entity can be mapped. How much detail is 
>mapped is up to the individual contributor.
This is largely true, however, the implication is also that the mapper can do this however they like. For the original point on traffic islands, I am strongly in favour of not separating carriageways where there is just a small traffic island for crossing purposes. There is a perfectly good tag that indicates that there is an island in the centre of the road. Splitting the highway does not provide any more information and makes the map confused.

>2. Landuse boundaries should not be attached to highways. The highway=* 
>tag represents the infinitesimally narrow centreline of the road. No 
>width is implied. Each renderer decides how to represent its width, or 
>use the width=* sub-tag.
In my view, the highway=* tag does not represent the centre of the road, it represents the complete highway. I accept that where fences are drawn then some landuse areas such as farmland may be better drawn up to the fence, (using common nodes with the fence). However, some of the landuse values are for non-physical things and so the edge is entirely arbitrary. For example if one side of the road is retail and the other side is residential, I consider it to be much better to align them both with the highway. This is very similar to boundaries - if a county boundary runs along a road, we do not say that the road is in neither county and draw boundary lines on both sides of the road. It is even more nonsensical to draw two landuse=residential areas, one on each side of a road with a gap between them. Quite clearly, if both sides of a road are residential areas then the area taken up by the road is also part of a residential area.

>The problem: A field boundary with a barrier=gate tag. When the boundary 
>is attached to a highway that gate also appears to be on the highway. An 
>obvious difficulty for routers.
Quite obviously the gate should be placed where it is sited (which is never on a junction). This is nothing to do with whether the landuse goes up to the highway.

Regards,
Mike

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