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

Sun Feb 5 18:21:07 UTC 2017

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 
  To: Rob 
  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 based on the lines between waymarks which does not accord 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 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).

  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 permissive and the line 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 
      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-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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