[Talk-GB] How to work with Government Open Data (e.g. Boundaries, Rights of Way)

[Gregory]

How do footpaths work legally with textual descriptions?
If a field has a stile/gate at opposite corners. The footpath may have
originally cut across, legally the landowner has to allow access between
the two gates, but can he make people walk round the edge of his field.
Also in reverse, if the footpath was originally walking round the edge
until people walked diagonally across and the landowner allowed that by
leaving a gap in crops and blocking the edge.
Has the footpath/access changed?

My point being that if that's fine, then we should map on-the-ground truth
between the gates and field boundaries. You can usually tell on the ground
which way the majority of people are walking across a footpath.

Of course there may be cases where changes are happening and we don't want
the map to support a case that nobody goes that way any more. If a farmer
starts growing crops over what has originally been a diagonal cut-across
footpath, and there are still a few people that walk that way (or you do)
then keep it mapped. If the majority of people are walking a longer way
around the edge (put off by the crops) then that could be tagged as a
non-designated footpath/path with only highway tag and maybe a note.


I have an example footpath I've mapped.
There is a stile in the middle of a non-farmed field, not part of a
fence/barrier http://www.openstreetmap.org/?node=264320738
I could have cut the corner a bit (not too much as it's slopped and has
large puddles), but I made sure I walked right to the stile when mapping. I
don't think it's ever going to be argued the footpath must meet that point,
but it's a useful navigation aid on the map. It would be confusing for a
map to have a stile that's separate stile to the path!

On 16 June 2012 16:28, <rob.j.nickerson at gmail.com> wrote:

> Hi Nick,
>
> I agree that we don't want to take Hants data at face value and load this
> into OSM where a path is already mapped. I have added my answers below:
>
> Q1. Hampshire marked footpath and OSM footpath run very close to each
> other (deviating by only a few meters max). No obvious marking on Bing
> Aerial
> Q2. As with Q1, but Bing Aerial shows clear path (neither OSM or Hampshire
> line up with this path perfectly).
>
> A1. Use OSM path and tag with designation
> A2. As A1 (optionally align path to Bing, GPS survey would help here).
>
> - - -
> Q3. OSM path crosses diagonally over a field (roughly following the path
> visible on Bing). Hampshire's data indicates a kink in the route so that in
> the middle of the field the gap reaches about 20-30 meters.
> Q4. OSM path crosses over 2 fields (following Bing path and cutting
> through a gap in hedgerow). Path is a straight line at an angle 'x' from
> the road. Hampshire's data shows the path runs straight, but at angle 'y'.
> Max deviation 50m. What about a smaller deviation of only 15m?
> Q5. As 4 above but the Hampshire path appears to cross the hedgerow where
> there is no visible gap on Bings imagery.
>
> A3-5. Research using other sources (ground survey, NLS scanned OS maps,
> etc). If no path found where Hants suggests there should be one, tag the
> OSM path instead (add a note). If there is a path where Hants puts it, then
> this should be mapped -> This could result in 2 paths being mapped, but
> would be correct if there are 2 paths on the ground.
>
> - - -
> Q6. Hampshire have a path marked that is not in OSM. Bing shows there is
> something there.
> Q7. As 6 but no marking on Bing. No obvious obstructions
> Q8. As 7 but there is an potential obstruction (e.g. woodland with no
> clear path - although this would be hard to see on Bing)
> Q9. As 8 but there is an obvious obstruction (e.g. building).
>
> A6-9. Trace the path from bing for Q6 (add a fixme tag). Q7-9 really could
> do with a ground survey.
>
> - - -
> To test these rules I had a go at mapping BOAT "Martin. 15". Neither OSM
> or Hants data lined up well with the Bing aerial (even with a simple
> offset). In this example there is a clear modern track. Two sections of the
> modern track appear to deviate from the historic route (I looked on the NLS
> maps to get a better idea of the historic route and cross referenced this
> with Bing aerial). The right hand section is still clearly visible on Bing,
> suggesting it is still used. The left hand section follows what looks to be
> a tree lined route. This suggests that I have identified the correct
> 'historic' route, but the trees make it hard to tell if the route is still
> passable.
>
> I mapped the whole of the 'modern' track as highway=track. The 2 other
> sections, I mapped as highway=path and added a fixme comment to suggest
> resurvey. I then added the designation=byway_open_to_all_traffic tag to the
> route that follows the 'historic' path. I was reasonable happy doing this
> because if the left hand section route is impassable there is a clear
> alternative. Let me know your thoughts on this.
>
> Visualisation of edit history:
> http://osmhv.openstreetmap.de/changeset.jsp?id=11915562#lon=-1.93345046;lat=50.9691551;zoom=15;layer=Mpnk
>
> - - -
> Do you think it is worth adding a wiki page (e.g. "Missing Rights of
> Way/Hampshire CC") where we can keep track of any 'big' issues with the
> intention to pass this data back to Hants? This could include a list of
> Ways in OSM that we feel may be a Missing RoW and a list of OSM ways that
> deviate substantially from the route Hants have in their database.
>
> Kind Regards,
> RobJN
>
> p.s. I'm not going to do many of the RoWs in Hampshire as I can't get down
> there to survey them. However, I am keen that we get a good 'best practice'
> in place so that we can use this to help persuade other councils to release
> their data (e.g. Work with us to improve your data), and to prevent
> differing approaches across the country.
>
>
>
>
>
> On , Nick Whitelegg <Nick.Whitelegg at solent.ac.uk> wrote:
> >
> > What I wouldn't personally like is a mess where the Hampshire ROW line
> *and* the line on the ground are *both* in OSM. This would make the data
> messy and confusing to work with.
> >
> > In cases like this maybe the ROW has, to all intents and purposes,
> shifted and the Hampshire data is out-of-date.
> >
> > Personally I would prefer that the Hants ROW data is *only* used to add
> *new, unmapped paths* to OSM and not to adjust existing paths - unless the
> existing path was mapped with some degree of uncertainty.
> >
> > Nick
> >
> > -----Rob Nickerson wrote: -----To: talk-gb at openstreetmap.org
> > From: Rob Nickerson
> > Date: 15/06/2012 06:18PM
> > Subject: Re: [Talk-GB] How to work with Government Open Data (e.g.
> Boundaries, Rights of Way)
> >
> >
> > Yeah, I think it might me a slow process but if there is a clear problem
> then may still be worth writing in to start the ball rolling.
> >
> > By keeping RoW and paths separate what do you mean? Add a way with a
> designation=public_footpath (for example) without the highway tag?
> >
> >
> > RobJN
> >
> > _______________________________________________
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> > Talk-GB at openstreetmap.org
> > http://lists.openstreetmap.org/listinfo/talk-gb
> >
> >
> >
>
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>


-- 
Gregory
osm at livingwithdragons.com
http://www.livingwithdragons.com
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