[Talk-GB] National Cycle Network discrepancies between Sustrans and OSM data

[Peter Neale]

Hi Ian,
I'd be happy to assist with ground surveys in the Milton Keynes area.  I note that there are a few discrepancies there.
I have raised one particular issue with both OS and Sustrans, but I have totally failed to get Sustrans' error corrected.  In order to head West, following Route 51 on the Sustrans map, you would have to cross a couple of fences, the West Coast Main Line and the A5 dual carriageway, all without "cheating" by using the nearby bridge and the ramped cyclepath, connecting the bridge to the way below it. 

For a screenshot, see:  https://www.dropbox.com/s/znhn73umb5fwf25/2023-02-25%20Sustrans%20OSM%20Difference.png?dl=0
The track mapped in OSM is an (reasonably) accurate representation of the on-the-ground "truth".
I would be happy to send you a copy of the documentation which I supplied to Sustrans, if you would like to try again to get them to correct their map. 
I have a second issue, which is another section of NCN 51, where it passes through several gates, when there is a parallel path, on the other side of the river, which would be much better suited as a National Cycle Route.  Again, I can provide documentation, if requested.
Regards,Peter(PeterPan99)

    On Saturday, 25 February 2023 at 20:49:28 GMT, Ian Dent <ian at dent.org.uk> wrote:  
 
   
 
 
I’ve been on a campaign to get the accuracy of the Sustrans National Cycle Network improved for quite a while now and have made some progress in engaging with Sustrans.
 
I’ve found that the NCN plotted on OpenStreetMap differs in a number of places from that in the Sustrans mapping.
 
I’ve created a coarse visualisation of the differences – see https://dent.org.uk/sustrans/sustrans-ncn-inconsistences/ - which, by focusing on the thick red and blue areas shows which areas to investigate in detail. Note this is a snapshot at Feb 23 and won’t reflect any changes in OSM or Sustrans data until I update it. Also note it is intended to show where to focus and some of the smaller focus areas may be errors in how I’ve done the mapping.
 
I know the Derbyshire NCN fairly well and have found that most of the discrepancies are due to errors in the Sustrans data rather than OSM and suspect this may be the case across the country. 
 
Sustrans have gone through a process of removing some of their routes and “reclassifying” others (i.e. not being responsible for them in the future). I’ve excluded these removed and reclassified sections from the map and the comparison with the OSM even though a lot of the routes still appear in OSM as they still have signage on the ground. I’m taking advice on what to do about removed and reclassified routes and will post a separate note on this subject later.
 
I’m keen that Sustrans internally review the discrepancies and make changes to their mapping when it is in error. I’ve had some success in discussions but it is a slow process! There is discussion about involving the Sustrans volunteer force who are very geographically spread and will have local knowledge.
 
I’m also keen to understand how best to communicate the discrepancy areas to people within the OSM community with local knowledge and who can, where the OSM is in error, make the necessary OSM changes.
 
Discrepancies are for various reasons including:
    
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mismatches on how the route is mapped (the map shows differences of 10 metres or more).
 
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Routes that Sustrans have classed as regional but OSM as national (or vice versa). e.g. NCN 30 south of Lowestoft, NCN 568 on The Wirral
 
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New Sustrans routes that haven’t yet reached OSM – e.g. NCN 28 east of Plymouth
 
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Routes that Sustrans classes as “links” but OSM has as NCN – e.g. NCN 28 near Dartmouth. I think these are generally Sustrans errors.
 
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Routes that OSM have included as NCN but which are not part of the Sustrans network. e.g. NCN 627 north of Sheffield, NCN 422 near Wokingham
 
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Some ferries are included as routes in OSM – e.g. NCN 2 near Plymouth
 
 
Sustrans data for the NCN can be found at https://data-sustrans-uk.opendata.arcgis.com/ (Open Government Licence). Note that a lot of this isn’t accurate so don’t take it as gospel – on the ground survey is needed.
 
I’ll continue to work with Sustrans to try and get their errors improved. I’d appreciate advice on how to get the OSM community to consider the discrepancies and fix any OSM errors found (local knowledge needed).
 
Thanks to those who’ve already discussed this with me – particularly the recent East Midlands OSM meeting.
 
Ian
 
 
 
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