[Talk-GB] Footpath Open Data is not always accurate.

Sun Feb 5 19:26:45 UTC 2017

Hi Rob,

I actually had the impenetrable barrier case 3 weeks ago: a stile deep in a
hedge & no sign of any path on the other side. It is in Leics CC data & a
path is shown on old 1:25k maps, so again I've added it without any highway
tag.

In Carmarthenshire the state of the paths was such that even signed ones
weren't worth adding to OSM: far too many disappeared through people's
gardens or petered out a few tens of metres from the road.

Jerry

On 5 February 2017 at 18:21, Rob <ra at care4free.net> wrote:

> Thanks to Colin and Jerry for your responses.
>
> Although I understand and agree with what you're saying Colin, I probably
> didn't make it clear enough in my attempt to be concise that it's the
> representation on OSM that I've got queries about as I'm fairly au fait
> with the law on this.  I'll refrain from tagging any sections of a path as
> a PROW even if it's only a little bit out.
> Thanks for the link to the government guide, which I wasn't aware of.  The
> Ramblers Association/Open Spaces Society's so-called Blue Book
> http://www.ramblers.org.uk/advice/rights-of-way-law-in-
> england-and-wales/the-blue-book.aspx is also worth knowing about.
>
> I think what I'll do is show the routes that are actually used, and where
> they deviate from the definitive route I'll tag them as permissive.
> However, even that isn't straightforward as any routes marked out by the
> farmer (as with a cereal crop) can vary from year to year, or not be marked
> at all.  When not marked an arbitrary route can often be seen or walkers
> might (as an example you gave, Jerry) use the field edge to reduce damage
> to crops.  The definitive route may be the only constant in such cases
> (except if legally changed).  I had it in mind that in some cases it
> could be appropriate to show both the PROW and the route that's normally
> used, so it's encouraging to see that you've done this.  I won't always
> apply this principle, though, as I don't think it's right somehow to show a
> PROW going through a house even when it does!
>
> Similarly, I'll have to think about whether to show a PROW going through
> an impenetrable hedge when there's an alternative route nearby.  If I do,
> I'll tag the appropriate node as a barrier with a suitable value.
>
> An associated issue is where a path is frequently obstructed or made
> difficult to walk by undergrowth and there's no alternative route due to
> barbed wire for example.  I guess one solution may be to show it but
> add the tag 'barrier:obstruction' in conjunction with a 'note' tag.
> (Thoughts?)
>
> I think I'll take each case on its merits as at the moment I can't see a
> 'rule' that will be sensible for everything.
>
> Cheers,
> Rob
>
>
> ----- Original Message -----
> *From:* SK53 <sk53.osm at gmail.com>
> *To:* Rob <ra at care4free.net>
> *Cc:* Talk-GB at openstreetmap.org
> *Sent:* Sunday, February 05, 2017 3:26 PM
> *Subject:* Re: [Talk-GB] Footpath Open Data is not always accurate.
>
> 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 <ra at 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.smale at xs4all.nl>
>> *To:* talk-gb at 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-engla
>> nd-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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