Hi Rob,

Generally the ideal is a path followed & mapped as it appears on the
ground, with the status (designation) of the path based on waymarkers and
fingerposts. This will inevitably mean that in places the mapped path does
not follow the line shown on the definitive map: most usually because
following the correct line over a field is not easy. (I've relatively
recently mapped a bridleway <http://www.openstreetmap.org/way/399058710>based
on the lines between waymarks which does not accord
<http://umap.openstreetmap.fr/en/map/ne-leics-footpath-mapping_120727#16/52.8132/-0.9196>
with the line provided by Leicestershire CC).

Frequently, the actual formal line of a PRoW may divert from the natural
line on the ground and this will only be apparent by close comparison with
the definitive map data. A good example
<http://www.openstreetmap.org/way/268238782> is a path which follows a
track to a sail-less windmill just S of Ockley in Surrey, the definitive
line actually follows the hedgerow. This was completely non-obvious on the
ground: no waymarks etc. It is likely that anyone following the path on the
ground would make the same assumption that we did, that the path follows
the track and then leads down directly to the hedge to the E. In this case
the diversion is minor, non-obvious (and if it's been followed without let
or hindrance for 20 years is a de facto PRoW anyway). So for reasons of
practicality it still makes sense to map it with the designation. Of course
if also makes sense to re-survey and double check for waymarks etc. on the
line from Surrey CC. (I've actually done this closer to Capel station &
failed to find suitable waymarks on a second survey for this path
<http://www.openstreetmap.org/way/269819287>).

In other cases it's much clearer. Around Scalford at our meeting 3 weeks
ago I came across several paths where the waymarks strongly suggested the
PRoW directly crossed the field, but there were no signs on the ground. In
general paths followed the headland round the field. In these cases I've
marked the actual visible paths <http://www.openstreetmap.org/way/466045435>
permissive and the line <http://www.openstreetmap.org/way/466045441> of the
PRoW just with the designation tags.

If mapping directly from OGL PRoW data the latter is actually all that one
can infer. Assuming that a path or track exists because there is PRoW is an
error: other evidence is needed. I'm aware of several short footpaths in
Nottinghamshire which aren't signed by the County Council because they dont
lead anywhere (e.g., one in Hicking and one off Nottingham Road, Trowell).

Note also that the GIS data provided is always clearly stated NOT to be
definitive. Only consultation with the description and the original
definition map can be relied upon.

Regards,

Jerry

On 5 February 2017 at 13:03, Rob <r...@care4free.net> wrote:

> Hi,
>
> I'm a relative newcomer to contributing to OSM but trying to get to grips
> as quickly as possible with the consensus on various topics, one of which
> is PROWs.  The emails below raise questions I've had for a while.
>
> I'm hoping for guidance as paths can include these two types:
> 1.  Definitive PROWs (but subject to subsequent Orders - whether
> deviations or extinguishments)
> 2.  De facto paths generally thought to be PROWs.
> Most of the time the two are coincident.
>
> Where they're not coincident, is it the case that we should map the de
> facto paths?
> In such a situation should the de facto paths be tagged as PROWs and/or
> given the highway authority's reference?
> Where there's a difference should we also map the definitive PROWs in some
> way (even if they go through a private house - I'm not making that up)?
>
> I realise there's an important but separate issue of copyright if the
> route can be determined only from the definitive map (based on the OS map).
>
> Regards,
> Rob
>
>
>
> ----- Original Message -----
>
> *From:* Colin Smale <colin.sm...@xs4all.nl>
> *To:* talk-gb@openstreetmap.org
> *Sent:* Sunday, February 05, 2017 11:33 AM
> *Subject:* Re: [Talk-GB] Footpath Open Data is not always accurate.
>
> My understanding is that the definitive data held by the appropriate local
> authority is exactly that, definitive. There may be legitimate errors in
> there of course, but where a path has been willfully and legally rerouted,
> that is a different type of error - lack of currency, i.e. an order has
> been made to reroute the path but they haven't yet got round to updating
> the Definitive Map and the Definitive Statement.
>
> Any paths that no longer follow the official route (as per the DM/DS)
> should not be tagged as PROW and probably as access=permissive unless they
> go across otherwise public land. The official route is still a public right
> of way, it's just no longer usable as such.
>
> Do you have a way of feeding these discrepancies back to Somerset CC, to
> establish whether they are true errors, lack of currency or illegal
> reroutings?
>
> http://www.ramblers.org.uk/advice/rights-of-way-law-in-
> england-and-wales/definitive-maps-explained.aspx
>
> --colin
>
>
>
> On 2017-02-05 11:19, Dave F wrote:
>
> Hi
>
> If you're using local authority data/os open data to map paths, as a
> contributor current is in Somerset, please don't assume their layout
> corresponds with what's on the ground or is more accurate than what's
> mapped in OSM. These official ways are often outdated, being based on
> redundant features such as grubbed up fences & hedgerows. Gate & stiles
> occasionally get moved. These tweaks often don't make it back to the
> Definitive Map.
>
> Please verify using this data doesn't make OSM less accurate.
>
> Cheers
> DaveF
>
> ---
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